S - 1) Standard; 2) Standard Pattern; 3) Sulphur; 4) Steam Sacrificial Anodes - the anodes which are used in cathodic protection, against corrosion. Sacrificial Metal - a base metal, used to cover a noble metal. The corrosion of the outer

sacrificial metal forms a protective coating over the noble metal; see Base Metal and Noble Metal.

Sacrificial Protection - Sacrificial Protection - prevention of electrolytic corrosion in a component by providing another

electrochemically more active metal close by and electrically connected to it. Sacrificial Protection - the property possessed by zinc, cadmium, aluminum and similar coatings

to protect an iron surface. SAE - Society of Automotive Engineers Safe Area - 1) nonhazardous (unclassified) location; 2) an area in which explosive gas/air

mixture are not expected to be present so that special precautions for the construction and use of electrical apparatus are not required.

Safe Fatigue Life - the period of time during which the continued applications of a load is extremely unlikely to result in failure.

Safe Impact Loading - the maximum acceleration to which equipment, etc., can get subjected under impact or shock without mechanical damage or operational break-down. The magnitude of the acceleration is given in multiples of g; its duration and its rate of change should be specified; also called Impact Load Factor.

Safety Factor - the provision of an extra margin in stress calculation, etc. to allow for errors and uncertainties. Thus a safety factor of two allows for twice the allowable stress calculated for a product specification.

Safety Plug - a protective device used on a heated pressure vessel (for example, a steam boiler), and containing a fusible element that melts at a predetermined safe temperature to prevent the buildup of excessive pressure; also known as Fusible Plug.

Safety Relief Valve - Safety Relief Valve - a pressure relief valve that can be used with gases, liquids, and vapors. Safety Relief Valve - an automatic pressure actuated relieving device suitable for use as either a

safety or relief valve, depending on application. Safety Relief Valve - an automatic pressure relieving device actuated by the pressure upstream

of the valve and characterized by opening pop action with further increase in lift with an increase in pressure over popping pressure.

Safety Relief Valve - see Safety Valve Safety Stop - a device that prevents mechanical over travel on a piece of equipment. Safety Valve - Safety Valve - a pressure relief valve designed for use with gases and vapors. Safety Valve - a spring loaded valve that automatically opens when pressure attains the valve

setting. Used to prevent excessive pressure from building up in a boiler. Safety Valve - a spring-loaded, pressure-actuated valve that allows steam to escape from a boiler

at a pressure slightly above the safe working level of the boiler; fitted by law to all boilers; also known as Safety Relief Valve.

Safety Valve - a valve which automatically discharges fluid to atmosphere so as to prevent a pre-determined safe pressure being exceeded.

Safety Valve - a valve which is controlled by a spring or weighted with a dead-weight, and fitted to a vessel or engine to allow the escape of steam, air or other gas when the internal pressure exceeds the maximum safe value. It acts without the application of any external energy, and the valve is designed to re-close and prevent any further flow of the fluid after normal pressure conditions have been resumed.

Safety Valve - a valve which operates automatically to discharge compressible gases or vapors from a system, to prevent a pre-set pressure being exceeded. These can also be pilot operated.

Safety Valve - an automatic pressure relieving device actuated by the static pressure upstream of the valve, and characterized by rapid full opening or pop action. It is used for steam, gas, or vapor service.

Saliferous - producing or containing salt; filled with salt

Salt Bath - a bath of molten salts used for heat treatment, i.e. for hardening, tempering or solution treatments. Salt baths give rapid, uniform heating and protect against oxidation. Different salts are used for different temperatures. An electric salt-bath furnace is a conductor-type electric furnace in which the salt is melted by the passage of the current.

SAM - Subsea Accumulator Module Sample - one or more portions of a liquid or solid material taken in an unbiased manner from a

batch, heat, lot or process stream to be representative of the whole, for subsequent testing to determine the chemical, physical, mechanical, or other quality characteristics of the material, or combination thereof.

Sampling Plan - a plan stating sample sizes and the criteria for accepting or rejecting items or taking another sample during inspection of a group of items.

Sampling Valve - Sampling Valve - a valve which is fitted to a pipeline to allow samples of a fluid to be withdrawn

for analysis. Sampling Valve - a valve which is fitted to a reactor or pipeline to allow small sample of a fluid to

be withdrawn for further testing. In simple cases a standard gate or needle valve, for example, may be used. The disadvantage is that inappropriate use may result in spillage. As an alternative, valves are available which ‘trap’ a small quantity of fluid in a chamber; and only this small amount of fluid is released when the valve is operated.

Sampling Valve - a valve which is used to take off a small quantity of fluid for test purposes. Sand Blasting - Sand Blasting - a compressed air impact cleaning process. In this process a high velocity stream

of compressed air along with abrasive particles is directed by means of blast gun against the metal surface. The blast gun is designed to converge air at high velocity into a mixing chamber. The abrasive is fed into this chamber through a side tube by suction feed, gravity feed or direct pressure. In small guns, the abrasive is drawn in the mixing chamber due to the vacuum created by the passage of high velocity air. The blasting operation is carried out in special cabinets and rooms. The metal to be blasted is placed over the trolley and rolled inside the cabinet. The operator direct the blast against the surfaces to be cleaned. Care is needed that blast is forced from different angles to clean all the surfaces. Small size metals are cleaned in cabinets equipped with windows. The operator manipulates the gun and the blast from outside. Unlike tumbling, sand blasting operation is suitable for fragile and large-size metals. The metals cleaned by this process possess good polish.

Sand Blasting - a method of cleaning metal surfaces by sand, steel shot or grit blown from a nozzle at high velocity.

Sand Blasting - a method of removing all surface impurities from old metal surfaces and consists of forcible driving under pressure hard particles of sand, causing controlled erosion of the surface against which the blast is directed.

Sand Blasting - grit blasting, especially when the abrasive is ordinary sand; see Grit Blasting. Sand Blasting - refers to a method of cleaning metal surfaces with sand sprayed over them

through a nozzle at high velocity. Sand Blasting - the terms “Sandblasting”, “Abrasive Blasting”, and “Blasting” are interchangeable

and refer to open, dry or wet blasting of surfaces using abrasive materials to develop an anchor profile on the surfaces to be coated.

Sand Blasting - the use of compressed air mixed with sand to discharge a high velocity stream of sand. The sand particles act as an abrasive to remove paint or to provide a decoration texture to a smooth concrete wall.

Sand Casting - a pattern is embedded in sand and then removed to leave a cavity of the needed shape and size. Metal is then poured into the cavity, where it cools to form a casting.

Sandwich Ball Valve - a ball valve in which the valve is made up of three pieces incorporating a body and two body connectors, the later featuring body ends. The design is so arranged that the body can be removed from the line leaving the body connectors attached to the mating pipework without any significant lateral displacement of the

latter. Saturated Vapor - a vapor whose temperature equals the temperature of boiling at the pressure

existing on it. Saunders Valve - see Weir Diaphragm Valve SAW - Submerged Arc Welding SBC - Split Body Construction SBFL - Spectacle Blind Flange SBR - Styrene - Butadiene Rubber (Buna - S) SC - Swing Check Valve Scabs - Scabs - elongated patches of loosened metal which have been rolled into the surface. Scabs - forms of projection on a casting which occur when a portion of the mold face or core lifts

and the metal flows beneath it in a thin layer. Scabs can be classified as a) expansion scabs, and b) erosion scabs. An expansion scab is caused in a casting by the expansion of surface layers of the sand mold. It may occur on any part but mainly occurs where to sand gets strongly heated. Due to excessive heat from the molten metal, the mold gets heated first by radiation and then by actual contact with the molten metal. Excessive heat causes a thin layer of the top sand to dry up and expand, leaving the interior green. It causes strains and cracks. It thus appears asa shallow, flat topped projection on the casting. Olivine or zircon sand are less prone to scabbing than silica sand due to their lower thermal expansion. Erosion scab occurs when the metal has been agitated or has partly eroded the sand. It leaves behind a solid mass of sand and metal at the spot where erosion took place. Erosion scabs are mainly caused by hard and uneven ramming.

Scale - Scale - 1) a thick metallic oxide, usually formed by heating metals in air; 2) a hard coating or

layer of materials on surfaces of boiler pressure parts. Scale - a crusty or flaky deposit formed on a surface. Scale - a dense deposit bonded on the surface of a tube in a heat exchanger or on the surface of

an evaporating device. Scale - excessive oxidation; a coating of oxide formed on heated metal. Scale - the oxide of iron that forms on the surface of steel after heating. Scale - the oxidized surface of steel which is produced during hot working or by exposure to air or

steam at high temperature. Scaling - Scaling - 1) a misnomer for descaling; 2) forming a thick layer of oxide on a metal, especially at

high temperatures. Scaling - oxidation Scaling - removing scale (rust or salt) from a metal or other surface. Scalp - to remove the surface layer of a billet, slab or ingot, thereby removing surface defects

that might persist through later operations. Scarfing - 1) tapering the ends of materials for a lap joint, so that the thickness at the joint is

substantially the same as that on the other side of it; 2) preparing metal edges for forge welding.

Scavenging - Scavenging - an addition made to molten metal to counteract an undesired substance. Scavenging - removing dissolved gases or other impurities from molten metal by reaction with an

additive. SCC - Stress Corrosion Cracking SCFH - Standard Cubic Feet per Hour SCFM - Standard Cubic Feet per Minute SCH - Schedule (Pipe Wall Thickness) Sch. or Sched. - Schedule (Pipe Wall Thickness) Schedule - Schedule - 1) a list or inventory; 2) a supplement to a document Schedule - a system for indicating the wall thickness of pipe. The higher the schedule number,

the thicker the wall for a certain pipe size. Schematic Drawing - a drawing of the general arrangement or outline of an object or its parts. Schematic Drawing - Schematic Drawing - a diagrammatic or preliminary drawing concept (scheme) as opposed to

definitive working drawings. Scintillation Counter - a device for detecting very low levels of radiation. Sclerometer - Sclerometer - an instrument that determines hardness of a material by measuring the force

needed to scratch or indent the surface with a diamond point. Sclerometer - an instrument use to determine the hardness of a material by measuring the

pressure needed to scratch or indent a surface with a diamond point. Sclerometer - an instrument which is used for measuring hardness. It consists of a diamond at

one end of a lever attached to a vertical pillar. The diamond gets loaded and the pillar rotated to make a scratch of standard depth, the weight in grams to produce this depth giving a measure of the hardness.

Scleroscope - Scleroscope - an instrument that determines hardness of a material by measuring the height to

which a standard steel ball rebounds when dropped from a standard height. Scleroscope - an instrument used to determine the hardness of a material by measuring the

height to which a standard ball rebounds from its surface when dropped from a standard height.

Scleroscope Hardness Test - Scleroscope Hardness Test - refers to a method of estimating the hardness of a metal by

measuring the rebound from it of a standard diamond tipped test weight dropped from a given height.

Scleroscope Hardness Test - the determination of the hardness of metals by measuring the rebound of a diamond tipped hammer, weighing about two grams (one-twelfth of an once), when dropped from a given height.

SCM - Subsea Control Module Scorching - premature curing or setting up of raw compound during processing. Scoring - Scoring - deep scratches on the surface of a metal. Scoring - scratching the surface of a material. Scotch - a wedge or block to prevent turning or slipping of a wheel or other movable part. Scotch Yoke - Scotch Yoke - a type of four bar linkage used to convert uniform rotation into simple harmonic

motion. Also converts linear motion to rotary motion. Scotch Yoke - a type of four-bar linkage; it is employed to convert a steady rotation into a simple

harmonic motion. Scouring - Scouring - 1) physical or chemical attack on internal surfaces of process equipment; 2)

mechanical finishing or cleaning using a mild abrasive and low pressure. Scouring - physical or chemical attack on process equipment surfaces, as in a furnace or fluid

catalytic cracker. Scrap (Ferrous) - ferrous (iron-containing) material that generally is remelted and recast into

new steel. Integrated steel mills use scrap for up to 25% of their basic oxygen furnace charge; 100% of the mini-mills' raw material for their electric furnaces generally is scrap.

Scratch Hardness - 1) a measure of the resistance of minerals or metals to scratching; for minerals it is defined by comparison with 10 selected minerals comprising the Mohs scale; 2) a method of measuring metal hardness in which a cutting point is drawn across a metal surface under a specified pressure, and hardness is determined by the width of the resulting scratch.

SCRD - Screwed End (NPT) Screw - 1) a cylindrical body with a helical groove cut into its surface; 2) a fastener with

continuous ribs on a cylindrical or conical shank and a slotted, recessed, flat, or rounded head; also known as Screw Fastener.

Screw Bonnet - Body and Bonnet Threaded Together Screw Dowel - a metal dowel pin having a straight or tapered thread at one end. Screw Down Stop and Non Return Valve - Screw Down Stop and Non Return Valve - a non-return valve which incorporates a mechanism

which can hold the disc in the closed position independently of the flow or, alternatively, can restrict the lift of the disc. NOTE: screw-down stop and non-return valves differ from globe valves only in that the disc is not attached to the stem. In some types a dashpot and piston are incorporated with the disc as in the piston type non-return valve. Therefore the definitions of components and trim as given in section 1 of this standard will apply, together with those definitions of components for the piston type non-return valve in this section, where applicable; also variously called Screw-Down Check and Flood Valve, Controllable check Valve, Controllable Non-Return Valve.

Screw Down Stop and Non Return Valve - screw-down check and flood valve, controllable check valve, controllable non-return valve.

Screw Down Stop Check Valve - a check valve having a mechanism to hold the disc in the closed position independently of the flow or to restrict the lift of the disc.

Screw Down Stop Check Valve - a type of check valve which incorporates a mechanism which can hold the disc in the closed position independently of the flow, or alternately, can restrict the lift of the disc.

Screw Down Stop Check Valve - see Screw Down Stop and Non Return Valve Screw Down Stop Valve - Screw Down Stop Valve - a type of valve in which the disc is lifted from and lowered on to the

body seat by a stem whose axis is at a right angle to the face of the body seat. This valve category includes globe, needle, angle, elbow, and oblique valves.

Screw Down Stop Valve - a valve in which the disc is lifted from and lowered on to the body seat by a stem whose axis is perpendicular to the face of the body seat.

Screw Fastener - see Screw Screw Gear - a gear consisting of an endless screw that meshes with a gear or pinion. Screw Thread - a helical ridge formed on a cylindrical core, as on fasteners and pipes. Screwed End - a type of end fitting on a valve or other fluid component which is joined by

threaded connections. Screwed Gland - Screwed Gland - a gland which gets adjusted by a special nut, the gland nut, to engage with a

stuffing box. Screwed Gland - a type of gland which is adjusted by a nut which engages the stuffing box, stem

or ball shank. Screwed Gland - a type of valve gland which is adjusted by a nut which engages the stuffing box.Screwed Nut - the nut of a screwed gland, by which pressure is transmitted to the gland. Scribe - to mark and cut the edge of a sheet of material in such a way that it will fit tightly against

an adjoining irregular surface. Scriber - a sharp-pointed tool used for drawing lines on metal work pieces. Scrubber - a device for the removal, or washing out, of entrained liquid droplets or dust, or for

the removal of an undesired gas component from process gas steams; also known as Washer or Wet Collector.

SCSSV - Surface Controlled Subsurface Safety Valve SDH - Side Drilled Hole SDRL - Supplier Document Requirement List SDS - Shut Down System SDU - Subsea Distribution Unit SDV - Shut Down Valve SE - 1) Screwed End; 2) Small End; 3) Stress range Seal - Seal - 1) any device or system that creates a nonleaking union between two mechanical or

process-system elements; for example, gaskets for pipe connection seals, mechanical seals for rotating members such as pump shafts, and liquid seals to prevents gas entry to or loss from a gas-liquid processing sequence; 2) a tight,

perfect closure or joint. Seal - 1) any device or system that creates a nonleaking union between two mechanical

components; 2) a perfectly tight closure or joint. Seal - any device used to prevent the passage of a fluid (gas or liquid). Seal Weld - Seal Weld - a weld that does not contribute anything to the mechanical integrity of an assembly,

but is made purely to seal or prevent leakage from, for instance, a threaded joint. Seal Weld - Threaded Joint Back Welded for Seal Seal Welded Bonnet - a bonnet welded to a body, at assembly, to provide a zero leakage joint.

This construction consists of a low strength weld with the bonnet retained to the body by other means to withstand the body pressure load acting on the bonnet area.

Sealant - Sealant - a compound used to fill and seal a joint as opposed to a sealer which is a liquid used to

seal porous surfaces. It is intended to remain elastic and bounded to the sides of a joint so that water tightness is retained with minor movement of the joint.

Sealant - a grease-like substance that is injected into lubricated plug valves to reduce operating force and to achieve a tight seal against internal leakage.

Sealed Ball Valve - a ball valve in which means of access to the valve does not utilize fixings and fastenings.

Seam - a mechanical or welded joint Seam Welding - Seam Welding - a resistance welding process in which pieces are joined due to heat produced by

resistance to flow of current. The electrodes used are circular in shape and the weld is in the form of a seam.

Seam Welding - a welding process in which pressure is applied continuously along the whole length of the lap joint to produce a seam weld. The metal pieces are held in two copper disc roller electrodes. A motor drives one of the electrodes so that pieces are moved in between the rollers in a suitable speed. In welding thin sections, intermittent current is passed by means of an interrupter with a duration ratio from 1:1 to 1:10. An interrupter is necessary because if a continuous heavy current is allowed to pass, high heat is generated. Due to high resistance, the metal gets melted on the surface and sticks to the electrode disc, thus spoiling it. As high current is passed between two electrodes, and workpieces are moved slowly between the two rollers, under pressure, the weld is completed. This process is used for producing pressure tight joints on oil drums, tanks, boilers, water pipes, refrigerators, motor car bodies, utensils and stoves. Materials like high carbon steel, mild steel, medium carbon steel, alloy steel, stainless steel, nickel and its alloys, copper and its alloys, aluminum and its alloys can be welded by this process.

Seam Welding - in it the parts are lapped and held in place under pressure. Seamless Pipe - pipe made from a solid billet, which is heated, then rotated under extreme

pressure. This rotational pressure creates an opening in the center of the billet, which is then shaped by a mandrel to form pipe.

Seams - open, broken surface running in straight longitudinal lines caused by the presence of oxides near the surface of a metal.

Season Cracking - Season Cracking - 1) a type of failure common to rods, tubes, sheets and other articles made of

brass or bronze due to initial internal stress; 2) a term applied to a stress corrosion of copper alloys, mainly brasses.

Season Cracking - a term usually reserved for describing stress corrosion cracking of copper or copper alloys in an environment that contains ammonium ions.

Seat - Seat - the fixed area of a valve into which the moving part of a valve rests when the valve is

closed to retain pressure and prevent flow. Seat - the fixed, pressure-containing portion of a valve which comes into contact with the moving

portions of the valve. Seat - the part of a valve against which the closure element effects shut-off.

Seat - the part of a valve against which the closure element presses to effect a seal. Seat - the portion of the body which is polished and aligned to provide the docking/receiving

surface against or into which the gate or poppet seals. Seat - the portion of the valve body that the flow control element contacts to seal against internal

leakage. It can be a separate part fastened in the body or can be integral with the body (a machined surface in the body).

Seat Angle - the angle between the axis of the seat orifice and the seating surface. A flat seated valve has a seat angle of 90 degrees. The seat angle of the closure member and seat may differ slightly to provide line contact.

Seat Joint - the area of contact between the closure member and the valve seat which establishes the sealing action.

Seat Leakage - the quantity of fluid passing through a valve when the valve is in the fully closed position with pressure differential and temperature as specified.

Seat Load - Seat Load - the contact force between the seat and the valve plug. When an actuator is selected

for a given control valve, it must be able to generate enough force to overcome static, stem, and dynamic unbalance, with an allowance made for seat load.

Seat Load - the total net contact force between the closure member and seat with stated static conditions.

Seat Retaining Ring - the component which locks the body seat ring in position. Seat Retaining Ring Fastening - the stud and nut, or set screw, which secures the retaining ring

to the body. Seat Ring - Seat Ring - a part of the flow passageway that is used in conjunction with the closure member to

modify the rate of flow through the valve. Seat Ring - a part that is assembled in the valve body and may provide part of the flow control

orifice. The seat ring may have special material properties and may provide the contact surface for the closure member.

Seat Ring - a ring-shaped part that is fastened in a valve body to be a body seat. It is used in gate, globe, check, ball, and high performance butterfly valves.

Seat Ring, Arched - a type of soft seat for ball valves where resilient seat rings are placed into circular recesses in the body, and seal against both the ball and the body. The seat ring is arch-shaped in cross section and flexes when contacted by the ball during assembly. The stresses produced by flexing are much lower than those produced by compression. Therefore the ring maintains its sealing pressure even with temperature and pressure fluctuations.

Seat Ring, Lip Type - a type of soft seat for ball valves where resilient seat rings are placed into circular recesses in the body and seal against both the ball and the body. The seat ring is made with a lip that flexes when contacted by the ball during assembly. The stresses produced by flexing are much lower than those produced by compression. Therefore the ring maintains its sealing pressure even with temperature and pressure fluctuations.

Seat, Back - Seat, Back - a machined seat, which may be on the bonnet or on a part separate from and

secured in the bonnet, which makes contact with the back face when the valve is fully open; also called Bonnet Back Face, or Spindle Seat.

Seat, Back - a machined seat, which may be on the bonnet or on a part separate from and secured in the bonnet, which makes contact with the back face when the valve is fully open.

Seat, Back - a seating surface in the bonnet area that mates with the closure member or valve stem in the extreme open position to provide pressure isolation of the stem seal.

Seat, Back - a shoulder on the stem of a gate or globe valve which seals against a mating surface inside the bonnet to prevent leakage of media through the bonnet stuffing box when the valve is fully opened.

Seat, Back - an auxiliary seat in the bonnet of a gate valve or globe valve that provides a seal between the stem and bonnet, to enable packing replacement while the valve is under pressure.

Seat, Conical - a design of a globe valve seat in which the seating surface of both the disc and

the seat ring are cone-shaped. Seat, Flat - a seat for a globe valve in which the seating surfaces of the discs and seat ring are

flat rings that are perpendicular to the direction of flow. Seat, Flexible - a seat design of a ball valve that provides controlled deformation of the non-

metallic seat rings when the valve is assembled. Seat, Integral - Seat, Integral - a flow control orifice and seat that is an integral part of the body or cage material

or may be constructed from material added to the body or cage. Seat, Integral - the flow control orifice and seat that is an integral part of the valve body or cage.

The seat is machined directly out of the valve body and is normally not replaceable without replacing the body itself - although some can be repaired by welding and re-machining.

Seat, Jam - a ball valve seat design in which the non-metallic seat rings are compressed (jammed) by the ball when the valve is assembled.

Seat, Resilient - a valve seat containing a soft seal such as an O-ring or plastic to assure tight shut-off.

Seat, Reversible - refers to the seat ring with seating surfaces on both sides such that when one surface has worn, the ring may be reversed to present a new surface to contact the closure member.

Seat, Soft - a seat ring that is made of non-metallic material. Seat, Spherical - a seat design of a globe valve in which the disc has a spherical seating surface

that mates with a conical seat ring surface to produce line contact. Seat, Spring Loaded - Seat, Spring Loaded - a seat design that utilizes a mechanical means, such as a spring, to exert

a greater force at the point of ball contact to improve the sealing characteristics, particularly at low pressure differential. The spring action may be accomplished by a metal spring arrangement or a compressed elastomer.

Seat, Spring Loaded - a seat utilizing a design that exerts a greater force at the point of closure component contact to improve the sealing characteristics, particularly at low pressure differential.

Seated, Soft - a term used to describe valve trim with an elastomeric or plastic material used either in the valve plug or seat ring to provide tight shutoff with a minimal amount of actuator force. A soft seated valve will usually provide CLASS VI seat leakage capability.

Seating Lock Locking Fastener - a locking fastener that locks only when firmly seated and is therefore free-running on the bolt.

Seating Surfaces - the contact surfaces of the closure member and seat which effect valve closure.

Seating, Downstream - Seating, Downstream - seating assisted by pressure differential across the closure component in

the closed position, moving the closure component slightly downstream into tighter contact with the seat ring seal that is supported by the body.

Seating, Downstream - seating is accomplished by pressure differential thrust across the ball in the closed position, moving the ball slightly downstream into tighter contact with the seat ring seal which is supported by the body.

Seating, Upstream - Seating, Upstream - a seat on the upstream side of a ball, designed so that the pressure of the

controlled fluid causes the seat to move toward the ball. Seating, Upstream - a seat on the upstream side of the ball, designed so that the pressure of the

controlled fluid causes the seat to move toward the ball. Secondary Creep - the change in shape of a substance under a minimum and almost constant

differential stress, with the strain time relationship a constant. Secondary Hardening - hardening of certain alloy steels by precipitation hardening during

tempering; the hardening occurring during this stage supplements hardening achieved by controlled cooling from above the critical temperature in a step that precedes tempering.

Secondary Stage Creep - in the second stage, creep occurs more or less at constant rate;

sometimes referred to as Minimum Creep Rate. This is an important part of the curve for most applications.

Secondary Steel - steel that does not meet the original customer's specifications because of a defect in its chemistry; gauge or surface quality. Mills must search to find another customer (that can accept the lower quality) to take the off-spec steel at a discount.

Segmented Ball - a closure member that is a segment of a spherical surface which may have one edge contoured to yield a desired flow characteristic.

Segregation - a phenomenon associated with solidification, which causes non-uniformity in chemical composition.

Seize Up - for a machine to become stiff or jammed, especially through overuse or lack of lubrication.

Seizing - abrasive damage to a metal surface caused when the surface is rubbed by another metal surface.

Seizure - seizing up, locking or partial welding together of sliding metallic surfaces normally lubricated, e.g. a journal or bearing.

Selector Valve - a directional control valve whose primary function is to selectively interconnect two or more ports.

Self Annealing - a term applied to metal such as lead, tin and zinc which recrystallize at ambient temperature and consequently exhibit little strain hardening when cold worked.

Self Contained Regulator - a valve with a positioning actuator using a self-generated power signal for moving the closure member relative to the valve port or ports in response and in proportion to the changes in energy of the controlled variable. The force necessary to position the closure member is derived from the fluid flowing through the valve.

Self Cooled Machine - a machine where the cooling is obtained by means of its own rotation. Self Locking Nut - a nut having an inherent locking action, so that it cannot readily be loosened

by vibration. Self Locking Screw - a screw that locks itself in place without requiring a separate nut or lock

washer. Self Relieving - the process by which excessive internal body cavity pressure is automatically

relieved either into the upstream or downstream line; it is generally found in ball valves.

Self Tapping Screw - a screw with a specially hardened thread that makes is possible for the screw to form its own internal thread in sheet metal and soft materials when driven into a hole; also known as Sheet-metal Screw and Tapping Screw.

Semi Finished Steel - steel shapes, for example, blooms, billets or slabs, that later are rolled into finished products such as beams, bars or sheet.

Semikilled Steel - Semikilled Steel - made by adding a comparatively lesser amount of aluminum than killed steel.

It reduces the cost of hot tops and the large percentage of metal discard when making mild steel. It produces some blowholes in the steel on solidification. Such blowholes weld more or less completely during hot rolling. Owing to the presence of piping, practically no material is discarded. Steel oxidized by this manner is also known as Balanced Steel.

Semikilled Steel - steel that is partially deoxidized so that there is a greater degree of gas evolution than in killed steel, but less than in capped or rimmed steel. The uniformity in composition lies between that of killed steel and rimmed steel.

Semikilled Steel - steel that is partly deoxidized during teeming so that only a small amount of dissolved gas is evolved as the metal solidifies.

Sems - a pre-assembled screw and washer combination. Sensitivity - the measure of the response of an instrument or control unit to a change in the

incoming signal. Sensitized Stainless Steel - any austenitic stainless steel having chromium carbide deposited at

the grain boundaries. This deprives the base alloy of chromium resulting in more rapid corrosion in aggressive media.

SEP - 1) Standard Engineering Procedures; 2) Standard Engineering Philosophy Separable Flange - a flange that fits over a valve body flow connection. It is generally held in

place by means of a retaining ring. This style of flange connection conforms to

ANSI / ISA 275.20 and allows for the use of different body and flange materials. Example: a valve with a stainless steel construction could use carbon steel flanges. This type of valve is very popular in the chemical and petrochemical plants because it allows the use of exotic body materials and low cost flanges; also known as Slip On Flange.

Separately Cooled Machine - a machine where the cooling is obtained by means other than its own rotation.

Separator - Separator - a device whose primary function is to isolate undesirable fluids and or contaminants

by physical properties other than size. Separator - a process vessel used to separate gases and various liquids. A Wellhead Separator

is the first process vessel in a production operation, the wellhead separator operates at or near wellhead pressures.

Sequence Valve - a valve whose primary function is to direct flow in a pre-determined sequence.Serrate - notched like the blade of a saw. Service - Service - operating conditions to be met Service - replacement of consumable material or items needed to keep equipment in operating

condition; it does not include preventive or corrective maintenance. Service - to perform services of maintenance, supply, repair, installation, distribution, and so on,

for or upon an instrument, installation, vehicle, or territory. Service Temperature - the maximum and minimum temperature of the media. Service Valve - in a pipe work system, a valve that isolates a piece of equipment from the rest of

the system. Servo - a device used to convert a small movement into a greater movement of force. Servo Valve - a directional control valve that modulates flow or pressure as a function of its input

signal. SES - Standard Engineering Specification Set - to become solid, rigid, firm Set Point - the target value which an automatic control device attempts to reach or to hold. Set Screw - Set Screw - a screw for adjusting or clamping parts of a machine. It prevents motion by exerting

pressure with its point. Set Screw - a screw, usually thread along the entire shank length, which is used to prevent

relative motion of a component by exerting pressure with its point. Set Screw - a small headless machine screw, usually having a point at one end and a recessed

hexagonal socket or a slot at the other end, used for such purposes as holding a knob or gear on a shaft.

Set Screw - a small, headless machine screw used for holding a knob, gear or collar on a shaft; it usually has a sharp or cupped point on one end and a slot or recessed socket on the other end.

Sfr - Swiss Franc SGA - Spur Gear Attachment SGBP - Shell General Business Principles Sgd - Singapore dollar SGS - Safeguarding System SH - 1) Short; 2) Short Pattern Shading Ring - usually, a round copper ring is pressed into a groove of the end stop in all AC

(alternating current) valves. The ring overcomes oscillation and chatter associated with AC valves. Silver shading rings are available when copper is not compatible with the media.

Shaft - Shaft - 1) a rotating rod that transmits motion; 2) the part of a ball, butterfly, or plug valve that

turns the flow control element. On a plug valve it is usually integral with the plug. Shaft - a cylindrical piece of metal used to carry rotating machine parts, such as pulleys and

gears, to transmit power or motion. Shaft - a reciprocating or rotating member usually within a cylinder; not in contact with walls.

Shaft - a revolving metal rod that transmits motion or power through axial rotation. Shaft - that part which support and/or transmit movement to the disc. Shaft Bearing - a bearing inserted in the shaft boss to support the shaft. Shaft Boss - a boss formed on the exterior of the body to support shaft; also called Trunnion

Boss. Shaft Cover - a cover used in the sealing of the non-driven end of the shaft. Shaft Cover Bolting - comprising bolts, stud-bolts, studs, set screws and nuts used for the

body/shaft cover connection. Shaft Cover Components - those parts which are associated, but not integral, with the shaft

cover. Shaft Cover Seal - any form of seal between the shaft cover and the body. Shaft Fixing - comprises the component used to secure the shaft to the disc. Examples of these

are : taper pins, dowels, key, bolts, stud and nuts. Shaft Seal - the component which forms the shaft sealing. Shaft Seal Retainer - the component which retains a non-adjustable shaft seal; also called End

Plate, or Gland Ring. Shaft Seal Retainer Bolting - comprises bolts, stud-bolts, stud, set screws and nuts used to

secure the shaft seal retainer to the body. Shaft Seal Retainer Gasket - a component for effecting a fluid-tight joint between the shaft seal

retainer and the body. Shaft Sealing - any form of seal, which may be adjustable or non-adjustable, between the shaft

and the body. Shaft Sealing Components - those parts which are associated with the shaft sealing. Shall - indicates a requirement Shall, Should, and,May - the word "Shall," is to be understood as a requirement, the word

"Should" as a Recommendation, and the word "May" as Permissive, neither mandatory nor recommended.

Shank - Shank - a long, narrow part of a tool or machine which connects the handle to the operating end;

a shaft, stem, or other long straight part. Shank - the cylindrical part of a screw or bolt (other than its head). Shape Correcting - rolling, heating and quenching steel sheets often affect the dimensions of

the steel. Levelers, temper mills and edge trimmers rework the processed steel to match customer specifications.

Shear - Shear - a deformation in which parallel planes in a body remain parallel, but get displaced in a

direction parallel to themselves. Shear - a strain produced by pressure in the structure of a substance, when its layers are laterally

shifted in relation to each other. Shear - a type of stress tending to separate solid material by moving the portions on opposite

sides of a plane through the material in opposite directions. Shear Face - the plane of the material which is subjected to shear from external forces. Shear Strain - 1) a deformation of a solid body in which a plane in the body is displaced parallel

to itself relative to parallel planes in the body; quantitatively, it is the displacement of any plane relative to a second plane, divided by the perpendicular distance between planes; 2) the force causing such deformation; also known as Shear.

Shear Strength - this is the ability of a material to withstand offset or transverse loads without rupture occurring. The rivet connecting the two bars shown is in shear while the bars themselves are in tension. Note that the rivet would still be in shear if the bars were in compression.

Shearing - Shearing - if the edges of sheet and strip are not controlled during reduction, they must be

trimmed parallel by shears. This process may be performed by either the steel mill or steel processor to match customer needs.

Shearing - the operation of cutting blank from continuous sheet for carrying further operation. Sheet Steel - thin, flat-rolled steel. Coiled sheet steel accounts for nearly one-half of all steel

shipped domestically (USA) and is created in a hot-strip mill by rolling a cast slab

flat while maintaining the side dimensions. The malleable steel lengthens to several hundred feet as it is squeezed by the rolling mill. The most common differences among steel bars, strip, plate, and sheet are merely their physical dimensions of width and gauge (thickness).

Shelf Aging - the change in a material's properties which occurs in storage with time. Shell - the parts of a valve that hold the fluid – the body, bonnet, cap, and so on. Shell parts are

also called Pressure-Retaining Parts. Sherardising - Sherardising - a particular process of producing a protective zinc coating on iron and steel. Sherardising - developed by Sherard Cowpercoles in 1900, it is a process of cementation using

zinc powders as a coating metal. Sherardising is used especially for small steel articles like bolts, screws, nuts and threaded parts. The main advantage is powdered zinc in which electric heating is employed.

Shielded Carbon Arc Welding - an arc welding process in which the arc is struck between a carbon electrode and the workpiece. Shielding is obtained by flux. The flux is supplied regularly from a blanket of container ahead of the weld.

Shielded Metal Arc Welding (SMAW) - a welding process carried out with DC welding equipment having a minimum current carrying capacity of 300 amps. All electrical leads, lighting gear, electrode holder, gloves, etc., are fully insulated. For striking the arc, the electrode is held in the electrode holder at an angle of 35-40 degrees to the surface of the plate and its end is struck against the plate. The process of welding is similar to Metal Arc Welding.

Shielded Metal Arc Welding (SMAW) - an arc welding process in which the arc is struck between the metal and the workpieces under a blanket of flux.

Shielded Metal Arc Welding (SMAW) - Shielded Metal Arc Welding (SMAW) - metals are heated with an arc between a covered metal

electrode and the work. Shielding is obtained from decomposition of the electrode covering. Pressure is not used and filler metal is obtained from the electrode.

Shielded Tungsten Arc Welding - it is carried out with a tungsten electrode. The process is similar to Shielded Metal Arc Welding.

Shielding - in welding terminology, the protection of quarry or tunneling work. Shipping and Storage Container - a reusable non-collapsible container of any configuration

designed to provide protection for a specific item against impact, vibration, climatic conditions, and the like, during handling, shipment, and storage.

Shipping Document - a document listing the items in a shipment, and showing other supply and transportation information that is required by agencies concerned in the movement of a material.

Shipping Time - the time elapsing between the shipment of material by the supplying activity and receipt of material by the requirement activity.

SHOC - Safe Handling Of Chemical Shock - a pressure increase considerably greater than the static working pressure, caused by a

sudden cessation of flow in a pipeline. Shoe - 1) a renewable friction element whose contour fits that of a drum and stops it from turning

when lateral pressure is applied. Also known as brake shoe; 2) a metal block used as a form or support during bending of tubing, wire, rod or sheet metal; 3) a generic term for machine elements that provide support, or separate two members, while allowing relative sliding motion.

Shop Standards - written criteria established to govern methods and procedures at an installation.

Shop Weld - Shop Weld - a weld made in a workshop. It is often better and cheaper than one made on a site. Shop Weld - a weld made in the workshop prior to delivery to the construction site. Shore A Hardness - see Hardness and Durometer Shore Hardness - a method of rating the hardness of a metal or of a plastic or rubber material. Shore Scleroscope - it is an instrument which is comprised of a small diamond-shaped hammer

which falls freely down a graduated tube of glass from a constant height. The hardness of the surface under test is measured by the height of the rebound. In

one type of this instrument the rebound of the hammer actuates the pointer of a scale so that the height of rebound could be recorded.

Short Pattern Valve - Short Pattern Valve - a valve design that has a face-to-face or end-to-end dimension less than

standard. Short Pattern Valve - having substantially full-area or reduced-area ports of rectangular or similar

shape, with restricted face-to-face dimensions. Short Term Creep Tests - a rupture test is carried out and the time to rupture is noted under

specified conditions of temperature and stress with only an approximate measurement of strain by a dial gauge during the course of experiments. Different strain curves are plotted and the creep is measured.

Shot - 1) small spherical particles of a metal; 2) small, roughly spherical steel particles used in a blasting operation to remove scale from a metal surface; 3) an explosive charge.

Shot Blasting - Shot Blasting - a mechanical impact cleaning process. The process implies hurling of abrasive

grit towards the metal to be cleaned by centrifugal force exerted by means of an impeller wheel. The abrasive used in this case consists of steel shot. The shot is directed over the metal at very high velocity, hitting the metal surface with enormous impact. Large cleaning units are equipped with one or more blasting impellers strategically positioned at different places, so that the metal can be cleaned thoroughly. Many shot blasting plants are equipped with rotating tables. The metals to be cleaned are carried by a power conveyor into the shot blasting machine for carrying out the operation. After the operation the metal is taken out and inspected.

Shot Blasting - a method similar to sand blasting for cleansing the surface of metals, using broken shot or steel grit instead of sand. It is less effective than sand blasting as the peening effect to the shot tends to drive unwanted deposits such as oxides into the surface.

Shot Blasting - to clean or strip a surface by directing a high-speed stream of steel particles at it. Shot Peening - Shot Peening - blasting the surface of a metal with small hard steel balls driven by an air blast to

harden the surface layers. Shot Peening - inducing compressive stresses in a material’s surface layer by bombarding it with

a selected medium (usually round steel shot) under controlled conditions. Shot Peening - superficial cold working, which is achieved by directing a stream of metal shot

onto the surface of a metal article. Should - indicates a recommendation Shoulder - a portion of a cylindrical machine element such as a shaft, screw or flange that is

larger in diameter than the remainder. Shoulder Screw - a screw with an unthreaded cylindrical section, or shoulder, between the

threads and screw head; the shoulder is larger in diameter than the threaded section and provides an axis around which close-fitting moving parts operate.

SHP - Safety and Health Passport Shrink Fit - Shrink Fit - a tight interference fit between mating parts made by shrinking-on, that is, by heating

the outer member to expand the bore for easy assembly and then cooling so that the outer member contracts.

Shrink Fit - a tight interference fit between mating parts where the amount of interference varies almost directly with diameter; parts are assembled by heating the outer member so that it expands, assembling the parts, and then allowing the outer member to cool and shrink onto the inner member; see also Force Fit.

Shrink Forming - Shrink Forming - a process for forming metal parts that uses a combination of mechanical force

and shrinkage of a heated blank to achieve final shape. Shrink Forming - forming metal wherein the piece undergoes shrinkage during cooling following

the application of heat, cold upset, or pressure. Shrink Ring - a heated ring placed on an assembly of parts, which on subsequent cooling fixes

them in position by contraction.

Shrinkage - Shrinkage - internal defect in castings that are internal voids, irregular in shape, caused by

volume contraction during solidification. It can be caused by not maintaining a fluid channel to the riser during solidification.

Shrinkage - the decreased volume of seal, usually caused by extraction of soluble constituents by fluids followed by air drying.

Shrinkage Cavity - a depression produced in a casting due to uncontrolled and haphazard solidification of the metal. It may be due to improper size gating system, inadequate risers or poor design of the casting. Too high pouring temperatures also produce shrinkage. This defect can be eliminated by creating conditions conducive to directional solidification of castings.

Shrinkage Effects in Casting - when a molten metal is allowed to solidify, it is found that the solid metal does not completely fill the mold. This is due to shrinkage of metal, which is caused by a) contraction in the liquid state between casting and freezing temperatures, b) shrinkage owing to solidification, and c) contraction in the solid state. All of the above types of shrinkages vary from metal to metal. The overall shrinkage in metals and alloys vary from 0 to 7%. In uneven section, stresses are set up in castings and may be sufficiently high to cause either warping or fracture. Solidification shrinkage needs consideration since it produces defects in ingots and castings.

Shunt - to divert all or part of a process flow away from the main stream and into a secondary operation, holding area, or bypass.

Shunt Valve - Shunt Valve - a valve that allows a fluid under pressure to escape into a passage that is of lower

pressure or can accommodate higher flow rates than the normal passage. Shunt Valve - a valve that gives a fluid under pressure a more readily available escape route than

the normal route. Shutdown Valve (SDV) - 1) pneumatic or hydraulic actuated valve, fail close. Shutdown valves

are typically used to close off the first separator from the second separator on a drilling platform; 2) an actuated valve installed in a pipeline or piping system which isolates a given process unit from an upstream or downstream inventory upon activation of the process unit alarm and shutdown system; compare withBlowdown Valve and Motor Operated Valve.

Shutoff Valve - Shutoff Valve - a manually operated valve used to isolate particular items of equipment or

sections of an installation in order to facilitate removal or site repair work. Shutoff Valve - a valve designed to operate fully open or fully closed, but not at an intermediate

position. Shutoff Valve - a valve that operates fully open or fully closed. Shutoff Valve - any device used in piping to shut off the flow of a fluid (liquid or gas). SI - SI - 1) Soft Iron; 2) Systeme Internationale d’Unites (International System of weights and

measures) Si - Silicon SI - the International System of Units is derived from the six basic units; meter, kilogram, second,

ampere, Kelvin and candela. SIA - 1) Secured Instrument Air; 2) Source Inspection Agency SIC - Shell International Chemicals Side Entry Ball Valve - a ball valve in which there is access for means of assembly from that

part of the valve body other than axial, top or bottom. SIEP - Shell International Exploration and Production SIL - Safety Integrity Level Silicon (Si) - Silicon (Si) - a shiny, gray, crystalline, non-metallic element with semi-conducting properties. Silicon (Si) - one of the principle deoxidizers used in steelmaking, and therefore, the amount of

silicon present is related to the type of steel. Silicon increases strength and hardness.

Silicon (Si) - silicon is a strong deoxidizer and improves the quality of steel. It is soluble in ferrite, and is a fairly effective hardener, and raises the Ac change points and Ar points when slowly cooled. There are three main types of silicon steel in common use: one in conjunction with manganese for springs, the second for electrical purposes, used in the form of a sheet for transformer cores and poles of dynamos and motors, that demand high magnetic permeability and electrical resistance, and the third is used as automobile valves. The presence of silicon in most steels is beneficial. As it has a tendency to graphitize, the amount is generally kept less than 0.4%.

Silicon Bronze - a corrosion resistant alloy of copper and 1 to 5% silicon that has good mechanical properties.

Silicon Electrical Steel - a type of specialty steel created by introducing silicon during the steelmaking process. Electrical steel exhibits certain magnetic properties, which make it optimum for use in transformers, power generators and electric motors.

Silky Fracture - a type of fracture surface appearance characterized by a fine texture, usually dull and non-reflective, typical of ductile fractures.

Siloxane - any of a class of compounds, varying from liquids to hard resins, whose molecules are composed of chains of alternate silicon and oxygen atoms, usually with hydrogen or hydrocarbon groups attached to the silicon atoms. The name “Siloxane” is based on the Si – O (Silicon – Oxygen) unit.

Silver Alloy Brazing - a brazing process in which a silver alloy is used for brazing; also known as Silver Soldering.

Silvers - surface ruptures in a metal somewhat similar in appearance to skin laminations, but usually more prominent.

Simmer - Simmer - detectable leakage from a safety relief valve at a pressure below the popping pressure. Simmer - the detectable leakage of fluid in a safety valve below the popping pressure. Simple Apparatus - a device which will neither generate nor store more than 1.2 V, 0.1 A, 25

mW, or 20 mJ. Examples are: switches, thermocouples, light emitting diodes, and resistance temperature devices (RTDs).

Single Phase - designating a circuit or device energized by a single alternating voltage, either in phase or 180 degrees out of phase; compare with Three Phase.

Single Sampling - a sampling inspection in which the lot is accepted or rejected on the basis of one sample.

Sink Mark - a depression on the outer surface of a molding, often an inevitable defect created at thick sections.

Sinter - Sinter - 1) to heat a mixture of powdered metals, usually under pressure, to the melting point of

the metal in the mixture which has the lowest melting point, which then binds together the harder particles; 2) a bonded mass of metal particles, shaped and partially fused by pressure and heating below the melting point.

Sinter - to make solid blocks from powder, using heat and pressure below the melting point. Sintering - 1) a process of cold pressing metals or powders into a desired shape and then using

heat to establish a strong bond; 2) a process employed for blending metallic powders which have been pressed into shape.

Sintering - a process that combines iron-bearing particles, once recovered from environmental control filters, into small pellets. Previously, these materials were too fine to withstand the air currents of the smelting process and were thrown away. The iron is now conserved because the chunks can be charged into the blast furnace; seeAgglomerating Processes.

Sintering - bonding of metal particles which are shaped and partially fused by pressure and heating below the melting point.

SIOP - Shell International Oil Products SIPM - Shell Internationale Petroleum Maatschappij B.V. SIS - 1) Safety Instrumented System; 2) Swedish Standard Site Conditions - the external factors, e.g. altitude, air temperature, wind velocity, vibrations,

earthquakes, relative humidity, voltage and frequency variations, etc., which may influence the operation of the machine.

Site Weld - a weld which is made during construction on a site.

Size Number - a number assigned to indicate inside and cross section diameters of an o-ring. Sizes established in SAE standard AS 568 have been adopted by the military and the industry.

Size Of Weld - in a fillet weld it is the leg length of the largest isosceles right triangle. In a groove weld it is the length of the groove.

Size, Actual - actual dimensions of the o-ring or other seal, including tolerance limits. Size, Nominal - approximate size of part in fractional dimensions. It may also indicate the actual

size of the groove into which a nominal size seal fits. Sizing - a finishing operation to correct surfaces and shapes to meet specified dimensions and

tolerances. Sizing Treatment - a surface treatment applied to glass used in reinforced plastics. Skelp - Skelp - mild steel strip, often of bessemer steel from which tubes are made by drawing it through

a welding bell, at welding temperature to produce butt welded or lap welded. Skelp - steel that is the entry material to a pipe mill. It resembles hot-rolled strip, but its

properties allow for the severe forming and welding operations required for pipe production.

Skin - the hard surface layer found on iron castings due to the rapid cooling effect of the mold, or on steel plates, strips and sheets due to rolling, or on other materials or products due to the surface hardening effect of the finishing process.

SL - Longitudinal Stress Slab - the most common type of semi-finished steel. Traditional slabs measure 10 inches thick

and 30-85 inches wide (and average about 20 feet long), while the output of the recently developed "thin slab" casters is approximately two inches thick. Subsequent to casting, slabs are sent to the hot-strip mill to be rolled into coiled sheet and plate products.

Slack - looseness or play in a mechanism Slackline - oil flow that does not completely fill a pipeline. Slag - Slag - the impurities in a molten pool of iron. Flux such as limestone may be added to foster the

congregation of undesired elements into a slag. Because slag is lighter than iron, it will float on top of the pool, where it can be skimmed.

Slag - the layer of waste material formed on the surface of molten metal ore during smelting and refining.

Slag Holes - smooth depressions or cavities on the upper surface of a casting or near it. Slag holes also occur near in gates or when the slag finds its ways into the mold cavity along with the molten metal. Two main causes of this defect are incorrect gating system and poor fluxing of metal.

Slag Inclusion - Slag Inclusion - a welding defect in which non-metallic solid material is entrapped in weld metal

or between weld metal and base metal. Mainly, slag enters the weld from the electrode. A dirty surface also produces defects. Design of joints play an important part in producing a sound weld, free from slag. The design must be such that it allows correct manipulation of electrode in order to avoid trapping of slag. In general, a slag is lighter than the parent metal and floats freely over the weld pool. It can be easily removed after solidification of weld.

Slag Inclusion - non-metallic solid material entrapped in a weld. Sleeve - a cylindrical part designed to fit over another part. Sleeve Bearing - a machine bearing in which the shaft turns and is lubricated by a sleeve. Sleeve Coupling - a hollow cylinder which fits over the ends of two shafts or pipes, thereby

joining them. Sleeve Lining - refers to the installation of a cylindrical sleeve of alloy material on the inside

diameter of a connection. Sleeve Valve - an admission and exhaust valve on an internal-combustion engine consisting of

one or two hollow sleeves that fit around the inside of the cylinder and move with the piston so that their openings align with the inlet and exhaust ports in the cylinder at proper stages in the cycle.

Slide - a common name for the gate of a knife gate valve. Slide Valve - Slide Valve - a sliding mechanism to cover and uncover ports for the admission of fluid, as in

some steam engines. Slide Valve - see Knife Gate Valve Sling Psychrometer - Sling Psychrometer - a device for determining relative humidity that consists of a wet and dry

bulb thermometer mounted in a frame that can be whirled about, usually by means of a handle and short piece of chain or wire rope attached to the upper end of the frame.

Sling Psychrometer - an hygrometer, which is held on a short length of chord and whirled around, the observer standing sideways to the air current. The wet-bulb is thereby rapidly reduced to its final reading.

Slip on Flange - a flange that slips onto a pipe and is welded in place. Slitting - cutting a sheet of steel into narrower strips to match customer needs. Because steel

mills have limited flexibility as to the widths of the sheet that they produce, service centers normally will cut the sheet for the customer.

Slot - Slot - 1) a long groove in a machine part into which another part slides; 2) a groove into which a

mating member can be inserted for the mechanism of torque, such as screwdriver slot.

Slot - a narrow, vertical opening Slot Washer - a lock washer with an indentation on its edge through which a nail or screw can be

driven to hold it in place. Slot Weld - a means of welding two plates together where a hole in one plate is filled with metal

and is bonded at the bottom to the backing plate. Slotted Head Screw - a screw fastener with a single groove across the diameter of the head. Slotted Nut - a regular hexagon nut with slots cut across the flats of the hexagon so that a cotter

pin or safety wire can hold it in place. Sluice Valve - a solid wedge gate valve used for waterworks purposes. Slurry - Slurry - a fluid consisting of small solid particles suspended in a liquid. Slurry - a suspension of fine solids in a liquid which can be pumped or can flow freely in a

channel. Slurry - material in a semi-liquid form; the suspension of solids in liquid. SMAW - see Shielded Metal Arc Welding SME - Subject Matter Expert Smelting - the process of strongly heating an ore so as to melt it. Smithing - forging or working iron or steel while hot. SMLS - Seamless SMTS - Specified Minimum Tensile Strength SMYS - 1) Specified Minimum Yield Strength; 2) Standard Measured Yield Strength SN - Serial Number Sn - Tin Snap Ring - Snap Ring - a form of spring used as a fastener; the ring is elasticity deformed, put in place, and

allowed to snap back toward its unstressed position into a groove or recess. Snap Ring - a type of retaining fastener in the shape of the letter C which is expanded across its

diameter and allowed to snap back into a groove to hold parts in position, and especially keep them from sliding axially along a shaft.

Snifter Valve - Snifter Valve - a valve on a pump that allows air to enter to escape, and accumulated water to be

released. Snifter Valve - a valve which opens for the passage of air but closes if liquids attempt to pass. Snubber - 1) a device which is used to damp the motion of the valve stem. This is usually

accomplished by an oil filled cylinder/piston assembly. The valve stem is attached

to the piston and the flow of hydraulic fluid from one side of the piston to the other is restricted; 2) a mechanical or hydraulic device for restraining motion; 3) a device installed between an instrument and the process used to protect the instrument from rapid pressure fluctuations.

SO - 1) Safety Officer; 2) Sales Order SO2 - Sulphur Dioxide Soaking - a phase of a heating operation during which metal is maintained at the requisite

temperature until uniformly heated, and / or until any required phase transformation has occurred.

Soap Bubble Test - a leak test in which a soap solution is applied to the surface of the vessel under internal pressure test; soap bubbles form if the tracer gas leaks from the vessel.

Socket - Socket - a device designed to receive and grip the end of a tubular object, such as a tool or pipe. Socket - a hollow for something to fit into, or stand firm, or revolve in. Socket Fitting - a fitting used to join pipe in which the pipe is inserted into the fitting. A fillet weld

is then made around the edge of the fitting and the outside wall of the pipe. Socket Head Screw - a screw fastener with a geometric recess in the head into which an

appropriate wrench is inserted for driving and turning, with consequent improved non-tamperability.

Socket Weld - an external weld joining the plain ended male portion and the corresponding socket. Used here as a male valve inlet in a process line or vessel socket.

Socket Weld End (SWE) - a valve end that is counter-bored to receive the connecting pipe, which is then fillet welded to the valve.

Socket Weld End (SWE) - Socket Weld End (SWE) - the end connection of a valve suitably prepared for socket welding to

a connecting pipe. Socket Welded - a valve or other fitting which slips over the end of a pipe and is made pressure

tight by welding. Sodium Hydroxide (NaOH) - a white crystalline solid that dissolves in water to form a highly

corrosive alkaline solution; used in petroleum refining and the chemical industry. Soffit - the internal surface of a pipe at the upper end of a vertical diameter; also called Crown. Soft Patch - a patch in a crack in a vessel such as a steam boiler consisting of a soft material

inserted in the crack and covered by a metal plate bolted or riveted to the vessel. Softening - Softening - 1) the end result of annealing or tempering, i.e. a reduction in hardness and strength;

2) a process for removing arsenic, antimony and tin from lead. Softening - reducing the hardness of a metal by heat treatment, usually tempering, but at times,

annealing primarily to facilitate machining. SOHIC - Stress-Oriented Hydrogen Induced Cracking SOHO - Senior Occupational Health Officer SOL - Sockolet SOLAS - Safety Of Life At Sea Solder - 1) to join two pieces of metal without melting them, by applying a layer of molten alloy to

the joint between them and allowing it to cool and solidify; 2) any of several alloys with a low melting point, often containing tin and lead, applied when melted to the joint between two metals to form an airtight seal.

Solder End - a valve end that is counter-bored to receive copper tubing, which is then soldered to the valve.

Soldering - Soldering - a method of joining metals using fusible alloys, usually tin and lead, having melting

points under 700° F (371° C). Soldering - the hot bonding of metal parts, using a thin film of low melting point alloy (solder). Soldering - the method of joining two metal parts by melting solder at a temperature lower than

the melting temperatures of the metals to be soldered. Soldered joints are generally weak. Soldering is applied to sheets, wires etc. at lower temperatures.

Solenoid -

Solenoid - a coil of wire usually in cylindrical form that when carrying a current acts like a magnet so that a movable core is drawn into the coil when a current flows and that is used especially as a switch or control for a mechanical device ( as a valve ). The solenoid turns on the valve.

Solenoid - a cylindrical coil of wire acting as a magnet when carrying electric current. It often contains a movable iron or steel core that can be used to operate a switch, relay, circuit breaker, etc.

Solenoid - a type of electromechanical operator in which reciprocal axial motion of a ferromagnetic core within an electromagnetic coil performs some mechanical function; common applications include opening or closing valves or electrical contacts; normally a solenoid armature is spring loaded so that the core moves against the action of the spring when the coil is energized, and the spring returns the core to its original position when the energizing electric current is turned off.

Solenoid Valve - Solenoid Valve - a shutoff valve whose position is determined by whether or not electric current is

flowing through a coil surrounding a moving iron valve stem; the valve may be normally open, in which case gas or liquid flows through the valve when electricity to the coil is turned off; normally closed, in which case gas or liquid flows only when electricity is turned on; or three way, in which gas or liquid flows in one path through the valve when electricity is off and in a different path when electricity is on.

Solenoid Valve - a valve actuated by a solenoid, for controlling the flow of gases or liquids in pipes.

Solenoid Valve - a valve that uses an electromagnetic coil for actuation. Solenoid Valve - a valve usually of the needle globe type where the closing member moves

under the action of an electrical solenoid. Solenoid Valve - an electromagnet with a moving core which serves as a valve, or operates a

valve; the valve is actuated by magnetic action by means of an electrically energized coil.

Solenoid Valve - an electro-magnetically operated valve which enables electrical control of the air supply to a pneumatic actuator. Double-acting actuators require a four-way solenoid, while the spring-return actuators require a three-way solenoid to achieve the proper supply-exhaust air flow patterns.

Solenoid Valve - solenoid valves are operated by an electrical solenoid. They are often deployed as piloting valves, i.e., fitted to actuators which in turn control larger valves.

Solenoid Valve - solenoid valves, typically of the needle globe type, are operated by an electrical solenoid. They are often deployed as pilot valves, i.e., fitted to actuators which in turn control larger valves.

Solid - the form of matter that has a definite shape and a definite volume. Solid Electrode Process - a gas metal arc welding process in which an external shielding is

formed by the gas and a molding shoe confines the molten metal for vertical position weldings. The plates to be welded are cleaned and placed in position. The welding gun is installed over the plates to be welded. The weld area is shielded by an inert gas (CO2 or argon) and an electrode is fed through the welding gun. The arc is struck between the workpiece and the electrode. The heat of the arc melts the electrode and the grooves faces. The molten metal is confined between the water-cooled molding shoes. The movement of the molding shoes are adjusted in such a way that they move upwards as the molten metals solidifies. Depending upon the welding conditions, two metal wires can be fed as electrodes. In this process no flux is needed.

Solid Phase Welding - in metals, sufficient pressure has to be applied to cause plastic flow of the two surfaces and to make large areas to come into intimate contact. This includes friction welding, indent lap welding, diffusion welding, high frequency welding, and explosion welding. These welds are made by the creation of a metallic bond between the two surfaces being joined. The surfaces to be joined are brought so close together that the atoms are separated by less than relaxationdistance.

Solid Solution - a single crystalline phase containing two or more elements. Solid State Welding -

Solid State Welding - a type of welding process in which coalescence is produced between the workpieces at temperatures below the melting point of the base metal, with or without a filler metal, but always with the application of pressure. Different solid state welding processes used in industry are: Forge welding, diffusion welding, inertia welding, explosive welding, cold welding, friction welding, and ultrasonic welding.

Solid State Welding - any welding process that produces a permanent bond without exceeding the melting point of the base materials and without using a filler metal.

Solid Wedge Gate - a flow control element of a gate valve made of a single piece with no measures taken to introduce flexibility.

Solution - a liquid mixture consisting of a solid or gas (the solute) and the liquid (the solvent) in which it is completely dissolved.

Solution Anneal - see Solution Heat Treatment Solution Heat Treatment - heating a metal to a suitable temperature and holding at that

temperature long enough for one or more constituents to enter into solid solution, then cooling rapidly enough to retain the constituents in solution.

Solvent Welding - a technique for joining plastic pipe work in which a mixture of solvent and cement is applied to the pipe end and to the socket, with the parts then being joined and allowed to set.

Sonic Flaw Detection - the process of locating imperfections in solid materials by observing internal reflections or a variation in transmission through the materials as a function of sound-path location.

Sonicate - to apply high-frequency sound waves to matter. SOP - Standard Operating Procedure SOR - Start Of Run Sorbite - Sorbite - 1) a phase of steel produced if plain carbon steel is heated to temperature range from

395° to 595° C, it changes into a structure called sorbite. In sorbite, cementite is in granular form. Sorbite is after and more ductile than troostite; 2) a product formed by the tempering of martensite to produce rounded particles of cementite in a ferrite matrix, thus distinguishing it from pearlite, which forms directly from austenite by eutectoid decomposition.

Sorbite - produced by tempering plain carbon steels between 450° and 630° C. It is softer than troostite and is commonly found in heat-treated constructional steels like axles, shafts and crankshafts.

Sorption - the term used to denote the combination of absorption and adsorption processes in the same substance.

Sour Crude - crude oil containing excessive amounts of sulphur, which liberate corrosive sulphurcompounds during refining; contrast with Sweet Crude.

Sour Gas - Sour Gas - a natural gas containing a significant amount of hydrogen sulfide (H2S). Sour Gas - natural gas containing significant amounts of hydrogen sulfide (H2S). It requires

special material treatments to avoid failures from Sulfide Corrosion Cracking. Sour Gas - natural gas that contains corrosive sulphur bearing compounds such as H2S or

mercaptans. Source Inspection - an inspection process of the purchased materials / equipment at the

vendor’s premises, conducted at regular intervals throughout the manufacturing or fabrication period.

Source Inspection Agency - a recognized and qualified third party organization with engineering expertise to conduct inspection on behalf of the contractor.

Source Inspector - a designated inspector of the appointed source inspection agency who does the inspection work at the vendor or sub-vendors premises.

SOV - Solenoid Valve SP - 1) Special Procedure; 2) Steam Pressure; 3) Stay Put; 4) Standard Practice Spacer - Spacer - a device for holding two members at a given distance from each other; also known as

Spacer Block.

Spacer - a pressure containing piece of equipment used to connect and provide separation between other pieces of equipment.

Spall - to break off thin chips from, and parallel to, the surface of a material, such as a metal or rock.

Spar - an installation that is anchored above a submarine manifold and which is designed for both storing oil and for loading tankers.

Spare Part - in supply usage, any part, component, or subassembly kept in reserve for the maintenance and repair of major items of equipment.

Spare Parts List - list approved by designated authorities, indicating the total quantities of spare parts, tools, and equipment necessary for the maintenance of a specified number of major items for a definite period of time.

Spark Lighter - a convenient process for lighting a welding torch. In it a grinding stone is used and a spark is produced by friction, igniting the torch.

Spark Test - Spark Test - refers to a method of determining the approximate composition of steel by holding a

sample on a grinding wheel and producing sparks. An experienced operator is able to detect differences in carbon content of steels of 0.05% in the range up to 0.35%and 0.10% in the range from 0.35 to 0.60%.

Spark Test - the spark test is frequently used for the identification of metals and alloys. When a piece of particular metal or alloy is held gently against a running grinding wheel, a specific pattern of sparking is produced, which helps in identifying the metals and alloys. The spark test is also used to identify the chemistry of steel. It requires a lot of practice and only by repeated practice does one become familiar with the chemical composition of materials. A fairly accurate identification is obtained by comparing the spark picture of the unknown with that of the known steel or metal. One main advantage of this test is that it can be applied to metals in practically all stages of production. Mild steel produces long white sparks and high carbon steel produces bushy streams with secondary bursts.

Spatter - Spatter - metal particle expelled during welding. It does not form a part the weld. Spatter - particles of molten metal expelled during a welding operation and becoming adhered to

an adjacent surface. SPC - Singapore Petroleum Company SPDC - Shell Petroleum Development Corporation SPDT - Single Pole Double Throw SPE - Society of Petroleum Engineers Special Bar Quality (SBQ) - SBQ represents a wide variety of higher-quality carbon and alloy

bars that are used in the forging, machining and cold-drawing industries for the production of automotive parts, hand tool,; electric motor shafts and valves. SBQ generally contains more alloys than merchant quality and commodity grades of steel bars, and is produced with more precise dimensions and chemistry.

Special Protection - a protection technique other than those that have been standardized. This type of protection is referred to by IEC as "Type s".

Specialty Steel - a category of steel that includes electrical (see Silicon Electrical Steel), alloy (see Alloy Steel), stainless (see Stainless Steel) and tool (see Tool Steels) steels.

Specialty Tube - refers to a wide variety of high-quality custom-made tubular products requiring critical tolerances, precise dimensional control and special metallurgical properties. Specialty tubing is used in the manufacture of automotive, construction and agricultural equipment, and in industrial applications such as hydraulic cylinders, machine parts and printing rollers. Because of the range of industrial applications, the market typically follows general economic conditions.

Specific Gravity - Specific Gravity - the ratio of the density of a substance to the density of some standard, such as

water (for a liquid) or air (for a gas). Specific Gravity - the ratio of the weight of a given substance to the weight of an equal volume of

water at a specified temperature. Specific Gravity - the ratio of the weight of a given volume of a substance to the weight of an

equal volume of water at 4° C.

Specific Gravity - the ratio of the weight of a given volume of a substance to the weight of an equal volume of some standard substance.

Specification - 1) a list of requirements that must be met when making a material, part, component or assembly; installing it in a system; or testing its attributes or functions; 2) a set of standard requirements applicable to any product or process within the jurisdiction of a given standards making organization; an industry consensus standard.

Specifications - Specifications - a document that defines the requirements that a finished product must conform

to; it may include chemical and mechanical properties, tolerances, marking, shipping, etc.

Specifications - an organized listing of basic requirements for materials of construction, product compositions, dimensions, or test conditions; a number of organizations publish standards (for example, American Society of Mechanical Engineers, American Petroleum Institute, and American Society for Testing and Materials), and manycompanies have their own specifications; also known as Specs.

Specifications - written data, drawings, and instructions that form the complete requirement the system must meet. This may include equipment lists, approved vendor lists, applicable company standards, and references to published standards (e.g., the National Electrical Code and ISA Standards).

Specifications - written instructions accompanying the drawings and describing the types and qualities of required workmanship and materials. By convention, specifications are usually bound together with other accompanying contract documents such as general conditions, supplementary conditions, invitation to bid, instructions to bidders, bid form, agreement, and addenda. Specifications are usually divided into divisions in accordance with the uniform construction index format.

Specular - having the properties of a mirror, especially a polished metal mirror. Speed Control - a valve used to meter flow and thus adjust actuating time. It incorporates the

use of an adjustable check valve which allows free flow in one direction and metered flow in the other.

SPEX - 1) Shell Philippines Exploration; 2) Specular Excluded Spherical Seated Bearing - a journal bearing in which the bearing liner is supported in such a

manner as to permit the axis of the journal to be moved through an appreciable circular angle.

Spheroidite - Spheroidite - a phase of steel produced by slow cooling of hypereutectoid austenite (steel

containing more than 0.83% carbon) or by reheating (temperature) magnetite in the range 650° to 705° C.

Spheroidite - formed by heating martensitic steels from 650° to 700° C. In this process, the needle-like structure is transformed to small spheres and the operation is known as spheroidizing.

Spheroidizing - heating and cooling to produce a spheroidal or globular form of carbide in steel. Spheroidizing methods frequently used are: a) prolonged holding at a temperature just below Ae1; b) heating and cooling alternately between temperatures that are just above and just below Ae1; c) heating to a temperature above Ae1 or Ae3 and then cooling very slowly in the furnace or holding at a temperature just below Ae1; d) cooling at a suitable rate from the minimum temperature at which all carbide is dissolved, to prevent the reformation of a carbide network, and then reheating in accordance with Method 1 or 2 above.

Spigot - a type of fitting, essentially a section of pipe fused cleanly into a valve. This protruding pipe is then fused into the piping system. Usually found in high purity systems.

SPII - Shipping, Packing and Invoicing Instructions Spike Welding - a resistance welding process in which a large amount of instantaneous stored

energy is used to form a weld. The electrical energy is stored in capacitors, which is released rapidly through the electrodes and the metal pieces to be joined. Current flow is controlled numerically for very little time. Due to high electrical energy the edges of the workpieces form a weld. It is a very rapid process. In this process the chances of war-page and contamination are eliminated. This process

is suitable for welding all types of metals and alloys having great variations in dimensions.

Spill - an unplanned or accidental loss of petroleum hydrocarbons from primary containment. Spin Welding - fusion of two objects (for example, plastics) by forcing them together while one of

the pair is spinning; frictional heat melts the interface, spinning is stopped, and the bodies are held together until they are frozen in place (welded).

Spindle - Spindle - a short, slender or tapered shaft. Spindle - see Stem Spindle - that component through which the load is transmitted to the valve head. Spindle Housing Cap - a cap which houses the top of the spindle and the adjusting screw. Spindle Key - used for opening and closing the valves of the gas cylinders. Spindle Lever Link - the component attached to the spindle which keeps the spindle in position

relative to the lever. Spinning - a cold metal working process that forces a circular piece of metal into a thinner

section. SPIR - Spare Parts and Interchangeability Record Spiral Wound Gasket - Spiral Wound Gasket - a gasket composed of alternate layers of preformed metal bands and

non-metallic filler. Spiral Wound Gasket - a requirement of any gasket is the ability to recover under variable loads.

The effects of pressure and temperature fluctuations, the temperature difference across the flange face, together with flange rotation, bolt stress relaxation and creep, require a gasket with adequate flexibility and recovery to maintain a seal under variable and uneven loading. The spiral wound gasket meets these requirements. A spiral wound gasket is manufactured by spirally winding a preformed metal strip and filler on the outside periphery of metal winding mandrels. The metal winding mandrel outside diameter forms the inner diameter of the gasket and the laminations are continually wound until the required outer diameter is attained. Normal practice is to reinforce the inner and outer diameters with several piles of metal with no sort of fillers being introduced. The winding material (hoop) can be Stainless Steel, Monel, Titanium, etc. with options of filler materials such as CAF (Compressed Asbestos Fiber), Non-asbestos jointing, PTFE, Flexible Graphite, ceramic, etc. Note: many Oil & Gas companies no longer allow CAF filler.

SPL - Sound Pressure Level Splash Zone - arbitrary area (-) 1.5 meters MSL (Mean Sea Level) to (+) 1.5 meters MSL. Splay - a slanted or beveled surface making an oblique angle with another surface. Spline - Spline - a strip of wood or metal fitting into a slot, usually to form a longitudinal side-to-side

connection between two members. Spline - any of a number of rectangular keys that fit into grooves in the shaft of a wheel and

which allow for movement. Spline - one of a number of equally spaced keys cut integral with a shaft, or similarly, keyways in

a hubbed part; the mated pair permits the transmission of rotation or translatory motion along the axis of the shaft.

Splined Shaft - a shaft with longitudinal gear-like ridges along its interior or exterior surface. Split Bearing - a shaft bearing composed of two pieces bolted together. Split Body - a valve body design in which trim is secured between two segments of a valve

body. Split Body - a valve whose body is split. This design allows for easy plug and seat removal.

Split-bodied valves are made in both the straight-through and angle versions. Split Body Ball Valve - a ball valve in which the valve comprises a body and body connector (s).

There are three main variants: a) two-piece ball valve, b) sandwich ball valve, c) constrained ball valve.

Split Nut - a nut cut axially into halves to allow for rapid engagement (closed) or disengagement (open).

Split Pin - a pin with a split at one end so that it can be spread to hold it in place.

Split Wedge Gate - a flow control element of a gate valve made of two separate pieces. SPMT - Self-Propelled Modular Transporters Sponge - wood shavings coated with iron oxide and used as a catalyst in processes for removing

hydrogen sulfide from industrial gases. Spot Facing - a finished circular surface around the top of a hole to seat a bolt head or washer,

or to allow flush mounting of mating parts. Spot Welding - Spot Welding - 1) to join by welding at a number of separate points; 2) to join metal with singular

circle welds. Spot Welding - a form of resistance welding where a weld nugget is produced along the interface

between two pieces of metal, usually sheet metal, by passing electric current across the joint which is clamped between two small diameter electrodes or between an electrode and an anvil or plate.

Spot Welding - a resistance method of welding sheets, etc, by passing current through the two surfaces lapping one over the other from electrodes which holds them tightly in contact, and repeating the process at regularly spaced intervals, so that the sheets are welded.

Spot Welding - a resistance welding process carried out at different spots on a workpiece, held between the electrodes under pressure.

Spot Welding - a series of spot welds made by circular or wheel type electrodes. Spot Welding - the joining of two or more thin metal plates at a number of spots by local heating

at these places with a heavy electric current for a short time. Spot Welding - the principle of spot welding is the same as that of electric resistance welding.

Electric supply, regulated by a transformer, is allowed to pass through high resistance at the point of weld, in between the tips of water-cooled copper electrodes. The electrodes are water-cooled to minimize the danger of overheating and softening of the tip which is occasionally filled to keep it clean and pointed. One end of the secondary winding of the transformer is connected to the upper moveable electrode and the other end is connected to the lower fixed electrode. The workpieces to be welded are pressed between the tips of the electrodes and a strong current at low voltage is switched on. Due to resistance offered by the workpieces to the flow of this current, the temperature at the contact surfaces rises to fusion point and the weld is completed on freezing. Operations are repeated by changing the position of the plate to get the weld at another place. Spot welding usually produces slight depressions or indentations on the workpieces. These are often undesirable on the show side of the finished products. Using large-sized electrodes can minimize these depressions. Metals like mild steel, hardenable steels, high speed steels, steels bits, stainless steel, coated steels, aluminum and its alloys, copper and its alloys, nickel alloys and Monel metal can be welded by this process.

Spotfacing - a flat surface for a nut or bolt to sit securely on. SPQP - Supplier’s Quality Control Plan Spring - Spring - a machined element which is capable of storing energy and releasing it as required. Spring - the loading medium of the valve Spring Bolt - a bolt which must be retracted by pressure and which is shot into place by a spring

when the pressure is released. Spring Bracket - a bracket on the valve body forming a support for the spring. Spring Loading Bolt - the bolt which attaches the spring to the body. Spring Pipe - that part of the valve, attached to the body, which encloses the loading spring;

also called Spring Case, or Spring Casing. Spring Pipe / Body Flange - the flange of the spring pipe to which the body is connected. Spring Pipe / Cover Flange - the flange on the spring pipe to which the cover is connected. Spring Pipe Bolting - comprises bolts, stud bolts, stud, set screws and nuts used for the

body/spring pipe connection and spring pipe/cover connection. Spring Pipe Bush - a bush in the spring pipe to guide the spindle. Spring Pipe Components - those parts which are associated, but not integral, with the spring

pipe. Spring Plate - a plate fitted at each end of the spring. Spring Rate - a term usually applied to self contained regulators describing the range of set point

adjustment available for a particular range spring. Spring Retainer - the component which retains the spring in the body. Spring Retaining Components - comprises nuts, pins and washers Spring Return - see Pneumatic Actuator Spring Steel - carbon or low alloy steel that is cold worked or heat treated to give it the high yield

strength normally required in springs; if it is a heat treatable composition, the springs may be formed prior to heat treatment (hardening).

Spring Temper - a level of hardness and strength for nonferrous alloys and some ferrous alloys corresponding approximately to a cold worked state two thirds of the way from full hard to extra spring temper.

Spring Washer - a washer consisting of a steel ring cut through and bent into helical form, which prevents a nut from unscrewing.

SPRT - Spacer Ring Type (ASME Flange) Sprue - Sprue - in casting, the passage through which molten metal from a pouring basin reaches the

mold cavity. It controls the flow of metal into the mold cavity. Sprue - the passage through which the molten metal from the pouring basin reaches the mold

cavity. It controls the flow of metal into the mold cavity. Sprue Marks - marks left on the surface of a rubber part, usually elevated, after removal of the

sprue or cured compound in the gate through which the compound is injected or transfer molded.

Spur Gear - Spur Gear - a gearwheel with teeth projecting parallel to the wheel’s axis. Spur Gear - a toothed wheel with radial teeth parallel to the axis. Spur Gear - the simplest of gears; in a gear set, the pinion and ring gear are aligned on parallel

shafts. It can be added to another gear operator to further increase the mechanical advantage afforded by the gear.

Spur Gear Operator - a gear operator set that uses a spur gear set. SPW - 1) Spiral Wound; 2)Spring Wound Square Operating Nut - a nut, usually 2" x 2", which is attached to a valve stem or the pinion

shaft of a gear operator, allowing use of wrenches to quickly operate the valve. Square Thread - a robust type of screw thread which can transmit thrust in both directions. Squeeze - cross section diametral compression of o-ring between surface of the groove bottom

and surface of other mating metal part in the gland assembly. Squirrel Cage - a form of rotor in small electric motors, resembling a squirrel cage (a rotating

cylindrical cage in which a small captive animal can exercise on as a treadmill). SR - 1) Spring Return; 2) Short Radius SRB - Sulphur Reducing Bacteria SRC - Specification Review Committee SRD - Supplier’s Required Documents SRE - Senior Resident Engineer SS - Stainless Steel SSB - Shell Sarawak Berhad SSC - Sulfide Stress Cracking SSE - Sime Sembcorp Engineering Sdn. Bhd. SSPC - 1) Sabah Shell Petroleum Company; 2) Steel Structures Painting Council SSS - Shell Sabah Selatan SSV - Surface Safety Valve ST - 1) Set; 2) Soft Seat (Nylon) ST / STL - Stainless Steel Stainless Alloy - any member of a large and complex group of alloys containing iron, at least 5%

chromium, and often other alloying elements, and whose principal characteristic is resistance to atmospheric corrosion or rusting; also known as Stainless Steel.

Stainless Steel (SS) - Stainless Steel (SS) - 1) a form of steel containing chromium, highly resistant to tarnishing, rust

and corrosion; 2) steel containing 10.5% or more chromium. Other elements may be added to secure special properties; 3) a steel that meets one of the following descriptions: (a) martensitic or ferritic chromium stainless steels containing more than 10% chromium (typically AISI 400 series), (b) austenitic chromium-nickel stainless steels containing more than 16% chromium and more than 6% nickel (typically AISI 300 series). This also includes the super austenitic stainless steels (with 6% molybdenum) and the alloys with nominally 20% chrome and 35% nickel such as Incoloy 825 or Alloy 20, (c) duplex ferritic-austenitic stainless steels containing approximately 15% to 30% chromium and 2% to 8% nickel (typically the 2205 and 2507 alloys).

Stainless Steel (SS) - can be 7 times the cost of ordinary steel Stainless Steel (SS) - corrosion resistant steel, more than 11% chromium. Stainless Steel (SS) - corrosion-resistant steel having from 10 to 35% of chromium with or

without the addition of nickel, manganese, silicon, cobalt, copper, molybdenum, tungsten, vanadium, niobium or titanium.

Stainless Steel (SS) - it is generally manufactured in an electric furnace. It is an iron-base alloy having chromium or chromium and nickel as alloying elements. Stainless steel possesses a great resistance to corrosion. There are two main types of stainless steels: Austenitic and Martensitic.

Stainless Steel (SS) - steel with more than 12% chromium. Chromium in steel forms a strong, passive chromium oxide protective film, making it corrosion resistant.

Stainless Steel (SS) - steels that do not rust due to the action of heat, moisture or atmosphere. Stainless Steel (SS) - the term for grades of steel that contain more than 10% chromium, with or

without other alloying elements. Stainless steel resists corrosion, maintains its strength at high temperatures, and is easily maintained. For these reasons, it is used widely in items such as automotive and food processing products, as well as medical and health equipment. The most common grades of stainless steel are: a) Type 304 - The most commonly specified austenitic (chromium-nickel stainless class) stainless steel; accounting for more than half of the stainless steel produced in the world. This grade withstands ordinary corrosion in architecture, is durable in typical food processing environments, and resists most chemicals. Type 304 is available in virtually all product forms and finishes; b) Type 316 - Austenitic (chromium-nickel stainless class) stainless steel containing 2%-3% molybdenum (whereas 304 has none). The inclusion of molybdenum gives 316 greater resistance to various forms of deterioration; c) Type 409 - Ferritic (plain chromium stainless category) stainless steel suitable for high temperatures. This grade has the lowest chromium content of all stainless steels and thus is the least expensive; d) Type 410 The most widely used martensitic (plain chromium stainless class with exceptional strength) stainless steel, featuring the high level of strength conferred by the martensitics. It is a low-cost, heat-treatable grade suitable for non-severe corrosion applications; e) Type 430 - The most widely used ferritic (plain chromium stainless category) stainless steel, offering general-purpose corrosion resistance, often in decorative applications.

Stainless Steel (SS) - any of a number of types of iron alloy with chrome, nickel, or other elements that does not oxidize in free air.

Stall Torque - the amount of torque provided by a motor at close to zero speed. Stalling Time - the time taken for any other part of the motor, when the motor is energized at

rated voltage and in the stalled condition, to be heated up from the temperature reached under full load and maximum coolant temperature condition, to the highest temperature which does not impair its subsequent performance.

Standard Cubic Foot of Gas - the quantity of a gas occupying one cubic foot at a pressure of one atmosphere or 0.10133 megapascals (14.696 psia) and a temperature of 15° Celsius (59° Fahrenheit).

Standard Fit - a fit whose allowance and tolerance are standardized. Standpipe - 1) a vertical pipe for holding a water supply for fire protection; 2) a high tank or

reservoir for holding water that is used to maintain a uniform pressure in a water-supply system.

Starting Current - the steady-state root-mean-square (RMS) current taken from the line over the starting period from zero speed to load speed with rated voltage and frequency applied.

Starting Torque - the electromagnetic torque generated by the motor minus the ventilation and friction torque losses of the motor, over the starting period from zero speed to load speed with rated frequency and voltage applied.

State of Strain - a complete description, including the six components of strain, of the deformation within a homogeneously deformed volume.

Static - passive; not changing; not moving; compare with Dynamic. Static Load - a load exerted on a bearing not in motion. Static Seal - Static Seal - a part designed to seal between parts having no relative motion; see Gasket. Static Seal - a seal between two surfaces which have no relative motion. Static Seal - see Gasket Static Unbalance - the net force produced on the valve stem by the fluid pressure acting on the

closure member and stem within the pressure retaining boundary. The closure member is at a stated opening with a stated flow condition. This is one of the forces an actuator must overcome.

Station Block Valve - a gate valve installed at the inlet (suction) side and the outlet (discharge) side of the pump station to isolate the pump station from the pipeline in the event of an emergency.

Statistical Process Control (SPC) - a technique used to predict when a steelmaking function's quality may deteriorate. By tightly monitoring the product's variance from specifications, the operator can determine when to apply preventative maintenance to a machine before any low-quality (secondary) steel is produced.

Stator - Stator - the part in an electric motor that does not move; compare with Rotor. Stator - the stationary portion of a machine that interacts with a rotor to produce power or motion.Stay Bolt - Stay Bolt - a bolt threaded through or welded at each end, into two spaced sheets of a firebox or

box header to support flat surfaces against internal pressure. Stay Bolt - a bolt with a thread along the entire length of the shaft; used to attach machine parts

that are under pressure to separate. Stay Put - the valve remains in the position it had prior to instrument air failure. Valve spring

action is defined in the requisition / indent. STBT - Stud Bolt With Nuts STD - 1) Standard; 2) Standard Wall Thickness Steady State Creep - see Secondary Creep Steam Cock - a valve for the passage of steam. Steam Jacket - a steam-filled casing that is fitted around a cylinder in order to heat its contents. Steam Trap - a device that automatically collects condensate in a steam line and drains it away. Steam Trap Valve - a self-adjusting valve which automatically separates steam from its

condensates and allows the latter to be used for other purposes, thus increasing the overall efficiency of a plant.

Steam Valve - a valve used to regulate the flow of steam. Steam, Dry - Steam, Dry - steam containing no moisture. Commercially dry steam containing not more than

one half of one percent moisture. Steam, Dry - steam with no water particles mixed in Steam, Saturated - steam in contact with liquid water at the boiling point Steam, Superheated - steam at any pressure which is heated to a temperature above the steam

temperature at that pressure. Steckel Mill - a reversing steel sheet reduction mill with heated coil boxes at each end. Steel

sheet or plate is sent through the rolls of the reversing mill and coiled at the end of the mill, reheated in the coil box, and sent back through the Steckel stands and recoiled. By reheating the steel prior to each pass, the rolls can squeeze the steel thinner per pass and impart a better surface finish.

Steel - Steel - a purified alloy of iron, carbon and other elements that is manufactured in the liquid state.

Most steels are almost free from phosphorus, sulphur, and silicon and contain between 0.1 and 1.5% of calcium. Mild steels are low carbon steels (less than 0.2%). They are malleable and ductile and are used in place of wrought iron. They are not hardened by being quenched (suddenly cooled) from a red heat. Medium steels containing from 0.2 to 0.6% carbon are used for making rails, and structural elements (beams and girders and so on). Mild steel and medium steel can be forged and welded. High carbon steels (0.75 to 1.5% carbon) are used for making scissors, surgical instruments, drills and other tools. Medium steels and high carbon steels can be hardened and tempered.

Steel - an alloy of iron and carbide and having less than 1% of all other components. Steel - any alloy of iron with up to 2% carbon that may or may not contain other alloying elements

to enhance strength or other properties. Steel - any of a number of iron alloys that contain small amounts of carbon, and in some alloys,

additional elements such as chromium, nickel, manganese, silicon, molybdenum, etc.

Steel Ingots - after melting steel to the required specification, it is cast into ingot molds. Great care is needed for making steel to exact specifications and casting in molds as it may give a number of defects at later stages of processes.

Steel Intensity - the amount of steel used per unit of gross domestic product. Intensity reflects the secular demand for steel, as opposed to cyclical demand. The amount of steel used in vehicles and the popularity of alternative materials affect the intensity, or how much steel is needed per unit produced. The state of the economy, however, determines the number of units.

Steel Strapping - banding and packaging material that is used to close and reinforce shipping units, such as bales, boxes, cartons, coils, crates and skids.

STEL - Stellite Stellite - Stellite - a material used in valve trim known for its hardness, wear and corrosion resistance.

Stellite is available as a casting, barstock material, and may be applied to a softer material such as 316 stainless steel by means of spray coating or welding; also called #6 Stellite or Alloy 6.

Stellite - any of a family of cobalt containing alloys known for their wear resistance, corrosion resistance, and resistance to softening at high temperature.

Stellite - see CoCr-A Hardfacing Stem - Stem - 1) the rod, shaft or spindle which connects the valve actuator with the closure member; 2)

the part, usually a rod or shaft, which connects to the valve stem and transmits motion (force) from the actuator to the valve. The actuator stem delivering an output thrust may or may not be the same stem as that on the power unit stem; 3) a rod connecting a knob or handwheel to the moving part it operates.

Stem - a spindle which can be manually rotated or automatically moved towards or away from a valve seat, in order to effect the closing or opening of valve. The end of the spindle is within the valve body, and in the proximity of the seat.

Stem - in a linear motion valve, the part which connects the actuator stem with the closure component.

Stem - the axial shaft in angle and inline valves connecting actuator and bellows assembly. Many valve stems rise as the valve is opened, while other valves may have a non-rising feature.

Stem - the component not integral with the closure member which passes through the body or cover and on which the stem head is formed.

Stem - the part of a gate valve, globe valve, or diaphragm valve that moves the flow control element.

Stem - the rod by means of which the disk or plug is moved to open and close a valve. Stem - the rod or shaft transmitting motion from an operator (handwheel or gear operator) to the

closure element of the valve. Stem - the valve component on which the actuating thread is formed and by which control of the

disc is effected. Stem - the Valve Plug Stem is a rod extending through the bonnet assembly to permit positioning

of the plug or closure member. The Actuator Stem is a rod or shaft which connects to the valve stem and transmits motion or force from the actuator to the valve.

Stem / Gate Connection - the means of attaching the gate to the stem. This is generally of the following forms: a) Tee Head, b) Button Head, c) Screwed and pinned, d) Belt Eye.

Stem Bearings - butterfly stem bearings are referred to as either the outboard or the inboard type, depending on their location, outside or inside of the stem seals.

Stem Boot - a protective device similar to a flexible bellows, used outside the bonnet to protect the valve stem from the surrounding atmosphere.

Stem Bush - that part, separate from and secured in the bonnet, which takes the thrust of the stem thrust collar.

Stem Bushing - see Yoke Nut Stem Button - Stem Button - the formed end of a valve stem to which the disc or disc holder is attached. Stem Button - the formed end of the stem to which the disc or disc holder is attached; also

known as Spindle Collar. Stem Connector - the device which connects the actuator stem to the valve stem. Stem Drive - that part of the stem which transmits torque to the ball. Stem Guide - Stem Guide - a guide bushing closely fitted to the valve stem and aligned with the seat. Stem Guide - a guide bushing closely fitted to the valve stem and aligned with the seat. Good

stem guiding is essential to minimizing packing leakage. Stem Head - 1) that part of the stem to which the wrench or other operating device is attached;

2) that end of the stem formed for the attachment of the gate. Stem Nut - Stem Nut - Operating Nut Stem Nut - see Yoke Nut Stem Nut - the threaded nut that surrounds a reciprocating valve stem and causes the stem to

move when the nut is rotated; also called Yoke Nut. Stem or Ball Shank Seal - the non-adjustable component(s) which form(s) the stem or ball

shank sealing. Stem or Ball Shank Seal Retainer - the component which retains a non-adjustable stem or ball

shank seal. Stem or Ball Shank Seal Retainer Bolting - comprises bolts, stud-bolts, studs, set screws and

nuts, used to secure the stem or ball shank seal retainer to the body cover. Stem or Ball Shank Seal Retainer Gasket - a component for effecting a fluid-tight joint between

stem or ball shank seal retainer and the body or cover. Stem or Ball Shank Sealing Components - those components which are associated with the

stem or ball shank sealing. Stem or Spindle - that component on which the actuating thread is formed and by which control

of the closure member is effected. Where this is two parts, the part to which the gate is attached is stem, and the part to which the hand wheel is attached is the spindle.

Stem Retaining Yoke - that external component which secures the stem in the valve. Stem Seal - Stem Seal - a pressure containing seal / packing to prevent leakage of the process fluid to the

atmosphere through the interfaces of the valve stem in contact with the valve body and adjacent parts.

Stem Seal - the part or parts needed to effect a pressure tight seal around the stem while allowing movement of the stem.

Stem Stop - a part fitted to the stem or spindle; also called Belt Eye Sleeve Stop. Stem Stop Nut - a nut which secures the stop to the stem spindle; also called Belt Eye Sleeve

Stop Nut. Stem Thrust Bearing - a bearing whose prime function is to take thrust and may also provide

stem sealing. Stem Thrust Collar - a collar formed on the stem of a non-rising stem valve.

Stem Torque - the force required at the valve stem to open or close the valve against system pressure and service conditions. Torque is usually expressed in inch pounds or foot pounds.

Stem, Integral - a design in which the stem is either physically a part of the ball or mechanically made part of the ball. Some integral stems are designed to perform a turning and then lifting action.

Stem, Loose - a design in which the stem is not physically or mechanically attached to the ball, but drives the ball through intimate contact of surfaces. Typical loose stem drives are: a) tang, b) pin, c) splined.

Stem, Non Rising (NRS) - Stem, Non Rising (NRS) - a gate valve having its stem threaded into the gate. As the stem turns

the gate moves but the stem does not rise. The stem threads are exposed to the line fluid.

Stem, Non Rising (NRS) - a stem design used on gate valves in which male threads on the stem mate with female threads in the valve gate. Turning the stem causes the gate to move, but the stem does not translate (rise).

Stem, One Piece - An inseparable Stem and Disc made from one piece of metal. Stem, Rising (RS) - Stem, Rising (RS) - a stem that comes out of a valve (rises) as the valve is opened. Stem, Rising (RS) - a valve stem that turns and rises when the valve is open. Stem, Rising (RS) - a valve stem with threads arranged so that as the stem turns, the threads

engage a stationary threaded area and lift the stem along with the closure element attached to it.

Step Bearing - a bearing that supports the lower end of a vertical shaft; also known as Pivot Bearing.

Sthene - the force which, when applied to a body whose mass is one metric ton, results in an acceleration of 1 meter per second per second; equal to 1000 newtons; formerly known as Funal.

Stick Slip - a function phenomenon which can be described as a jerky motion which sometimes results when one surface is dragged against another. Normally it is associated with a non-lubricated or boundary-lubricated condition.

Stiction - friction that tends to prevent relative motion between two movable parts at their null position.

Stiffness - Stiffness - 1) the ability to resist bending, or any type of elastic or viscoelastic deformation; 2) the

reciprocal of compliance, and equals the ratio of force to deflection. Stiffness - the ability of a metal to resist bending, stretching, shortening and twisting. It is defined

by the modulus of elasticity. The modulus applies only within the elastic range (the range within which a metal will return to its original shape if the load is removed). It is the ratio of stress to strain.

Stiffness - the ability to resist deformation under stress. Stiffness - the resistance a material offers to deformation below the elastic limit. It is needed in

crankshafts, springs, beams, machine parts and structural members in which the extent of elastic deformation or deflection under load is significant. The stiffness of a material is determined from the extent of deformation produced by any given load below the elastic limit. Under constant load, the smaller the elastic deformation, the stiffer the material in question.

Stiffness - the resistance of a material offered to deformation, below the elastic limit. The stiffness of a material is indicated by the slope of the stress-strain curve below the elastic limit. The greater the slope of the curve, the lesser the stiffness and vice versa. Modulus of Elasticity of a material refers to its stiffness in the elastic limit. The term flexibility is often used to refer to the opposite of stiffness.

Stiffness - the resistance offered to deformation, below the elastic limit of a material. The stiffness of a material is indicated by the slope of the stress-strain curve below the elastic limit. The greater the slope of the curve, the lesser the stiffness and vice versa. Modulus of Elasticity of a material refers to its stiffness in the elastic limit. The term flexibility is often used to refer to the opposite of stiffness.

Stitch Welding - making a welded seam using a series of spot welds that do not overlap.

Stoke - the standard unit of kinmatic viscosity in the CGS (Centimeter-Gram-Second) system. It is expressed in square centimeters per second; 1 centistoke equals 0.01 stoke.

Stop Check Valve - Stop Check Valve - 1) a check valve in which the closure member can be mechanically closed;

2) a lift check valve design that also has a stem that can be used to hold the disc against its seat and have the valve function as a stop valve; also called a Non-Return Valve.

Stop Check Valve - a check valve in which the closure member can be mechanically closed. Stop Cock - Stop Cock - a conventional term applied loosely to valves and cocks of many different types. Stop Cock - a small valve for stopping or regulating the flow of a fluid through a pipe. Stop Nut - 1) an adjustable nut that restricts the travel of an adjusting screw; 2) a nut with a

compressible insert that binds it so that a lock washer is not needed. Stop Stud - the component which restricts the travel of the cover. Stop Valve - Stop Valve - 1) a valve which, when shut, prevents the flow of liquid or gas; 2) the main steam

valve on a boiler for controlling the steam supply and isolating the boiler from the main steam pipe.

Stop Valve - a valve that can be opened or closed to regulative or stop the flow of fluid in a pipe. Stop Valve - a valve used only for starting and stopping fluid flow. Stop Valve - a valve which is used for controlling the flow of liquid or gas by turning it on or

completely shutting it off. Stops - 1) components or features of the valve which limit the rotary movement of the ball; 2)

parts integral with or fitted to the valve, to limit the turning angle of the plug. Stored Energy Welding - a welding process carried out by stored electrostatic, electromagnetic

or electrochemical energy. Stove Bolt - a coarsely threaded bolt with a slotted head, which with a square nut is used to join

metal parts. STP - Standard Temperature and Pressure Straight Polarity - a direct current arc welding process where the electrode acts as negative and

the workpiece positive; also known as Electrode Negative. Straight Through Valve - this valve offers a line of sight valve opening (generally somewhat

smaller than port I.D.) from inlet port to outlet port. It is a design particularly suited for metal closure seals.

Strain - Strain - change of shape or size of a body produced by the action of a stress. Strain - deflection due to a force Strain - refers to the change in shape or length of material when subjected to a force, the strain

producing a change in length being expressed as a ratio to original length. Strain - the change in length per unit length. Strain - the deformation per unit length produced in a solid as a result of stress. Strain - when a material gets distorted by external or internal forces acting on it, it is said to be

strained. Strain Aging - Strain Aging - a change in properties of a metal or alloy that occurs at room or slightly elevated

temperature following cold working. Strain Aging - refers to the gradual changes in physical and mechanical properties, generally an

increase in hardness, which takes place following cold working. At atmospheric temperature the change is slow; heating to, say, 200° Celsius may accelerate it. Such changes occur principally in iron and steel.

Strain Gauge - Strain Gauge - a device that can be attached to a surface, usually with an adhesive, and that

indicates strain magnitude in a given direction by changes in electrical resistance of fine wire; it may be used to measure strain due to static or dynamic applied loading, in tension or compression, or both, depending on design of the gage, bonding technique, and type of instrumentation used to determine resistance changes in the strain element.

Strain Gauge - a device which is used for converting mechanical strain into a measurable electrical signal. It consists of a very thin metal wire, metal foil or semiconductor filament bonded onto a backing sheet by which it can be attached to a body before it is put under strain. As the body gets strained, the electrical conductor gets correspondingly strained. This alters its electrical properties and with prior calibration the value of the strain is obtained. A Wheatstone Bridge circuit is used for static analysis and temperature compensated dynamic analysis, while a potentiometer circuit can be used for direct readout of dynamic analysis when temperature compensation is not needed.

Strain Hardening - Strain Hardening - if any material has been worked cold, such as a steel wire being drawn

through a die, it is said to be strain hardened. Strain Hardening - layers of atoms can slide relative to each other, which explains the malleability

of metals and their ability to be formed into complex shapes by mechanical pressure. Sometimes this is not an advantage in structural metals, and methods of processing are used to prevent the slippage of atoms. The boundary between the slipped and unslipped part of a crystal is known as a Dislocation Line, and these dislocations can be complex. If pressure is put on a metal, dislocations can interact and start to prevent slippage. This mechanism is called Strain Hardening, and there comes a point when the metal cannot be deformed further without fracture.

Strain Hardening - the increase in tensile and yield strengths, and the corresponding reduction in ductility, associated with plastic deformation of a metal at temperatures below its recrystallization range.

Strainer - Strainer - a coarse filter Strainer - a device through which a fluid is passed to remove insoluble materials. Strand Casting - the direct casting of steel from the ladle into slabs, blooms or billets. In strand

casting a heat of steel is tapped into a ladle in the conventional manner. The liquid steel is then teemed into a tundish which acts as a reservoir to provide for controlled casting rate. The steel flows from the tundish into the casting machine and rapid solidification begins in the open-ended molds. The partially solidified slab, bloom or billet is continuously extracted from the mold. Solidification is completed by cooling the moving steel surface.

Strength - Strength - properties related to the ability of steel to oppose applied forces. Forms of strength

include withstanding imposed loads without a permanent change in shape or structure and resistance to stretching.

Strength - the ability of a material to resist the effect of external forces. Steel has a higher mechanical strength than that of aluminum.

Strength - the resistance by which materials oppose deformation. Strength - the strength of any material measured by its maximum safe working stress. It is equal

to the yield point, ultimate strength or proof stress divided by the factor of safety appropriate to the material and conditions of loading.

Strength - the stress at which material ruptures or fails. Stress - Stress - force per unit of original cross section area Stress - it is force per unit area Stress - the force acting across a unit area in a solid material resisting the separation,

compacting, or sliding that tends to be induced by external forces. Stress - the force per unit area. There are three kinds: tensile, compressive and shear. Bending

produces both tensile and compressive stresses while torsion produces a shear stress. An alternating stress exists when a force keeps changing sign. An alternating stress can be superimposed on a steady stress and the resultant combination may be of alternating sign or the steady stress may so dominate that the resultant has been of one sign but, of course varying magnitude.

Stress Corrosion - Stress Corrosion - certain metallic alloys are susceptible to premature failure under sustained

tensile stress in a corrosive environment. This stress corrosion takes place when

the material is kept in a corrosive under tension of sufficient magnitude and duration to allow the initiation and growth of cracks. Failure then takes place at a stress which is lower than that which the material would normally be expected to withstand.

Stress Corrosion - the combined effect of static tensile strength and a corrosive environment on a metal.

Stress Corrosion Cracking (SCC) - Stress Corrosion Cracking (SCC) - cracking due to a combination of corrosion and stress. Stress Corrosion Cracking (SCC) - cracking of metal produced by the combined action of

corrosion and tensile stress (residual or applied). Stress Corrosion Cracking (SCC) - deep cracking in a metal part due to the synergistic action of

tensile stress and a corrosive environment, causing failure in less time than could be predicted by simply adding the effects of stress and the corrosive environment together. The tensile stress may be a residual or applied stress, and the corrosive environment need not be severe but only must contain a specific ion that the material is sensitive to.

Stress Corrosion Cracking (SCC) - slow growth of cracks in stainless steel caused by the combined effect of mechanical stress and exposure to a corrosive environment.

Stress Corrosion Cracking, Chloride - failure by cracking under the combined action of tensile stress and corrosion in the presence of chlorides and water.

Stress Crack - an external or internal crack in a solid body (metal or plastic) caused by tensile, compressive, or shear forces.

Stress Cracking, Sulfide (SSC) - brittle failure by cracking under the combined action of tensile stress and corrosion in the presence of water and H2S.

Stress Number Curve - a curve which is obtained from fatigue tests in which a series of specimens of a given material are subjected to different ranges of stress. The range of stress is plotted against the number of cycles required to produce failure. In steel and many other metals, there is a limiting range of stress below which even an infinite number of cycles will not produce failure. This is often known as the fatigue limit. The Stress- Number Curve is also called S-N Curve.

Stress Relief Annealing - heating metal to a point where there can be some re-crystallization, and then cooling. The temperature is usually raised to approximately 0.6 of the melting temperature of the metal; for steel, this is approximately 650° C. If the steel is cooled in air, it is called Normalized Steel. Stress relief annealing allows internal stresses in the metal to be relaxed, so further working can take place.

Stress Relief Heat Treatment - refers to a process of reducing residual stress in a metal object by heating it to 600° or 650° Celsius and holding at this temperature for sufficient time for the internal stresses to the released by creep.

Stress Relieving - Stress Relieving - a process of heat-treating to lessen of eliminate internal stresses in metal parts

that generally occur from fabrication, or other processes. It is usually done at a lower temperature than annealing or normalizing.

Stress Relieving - heating a metal to a suitable temperature, holding at that temperature long enough to reduce residual stresses, and then cooling slowly enough to minimize the development of new residual stresses.

Stress Relieving - heating to a suitable temperature, holding long enough to reduce residual stress, and then cooling slowly enough to avoid inducing new residual stresses.

Stress Relieving - heating to a suitable temperature, holding long enough to reduce residual stresses and then cooling slowly enough to minimize the development of new residual stresses.

Stress Relieving, Local - a stress relieving operation carried out only on a specific portion of a workpiece.

Stress Strain Relationship - the effect of increasing the stress on a material and its corresponding increase in strain which will have a unique relationship for each material. For stresses up to the elastic limit, the material will return to its original length upon removal of the stress, and over this length of the curve the ratio of stress over strain is a constant, known as Young’s Modulus of the material, and the material is obeying Hooke’s Law. Under the influence of loads inducing stresses

above the yield point, the material is no longer elastic and after passing through a plastic state will eventually fracture.

Stress Test - a test of equipment under extreme conditions, outside the range anticipated in normal operation.

Stress, Allowable - the maximum force per unit area that may be safely applied to a solid. Stress, Breaking - Stress, Breaking - the crushing strength of a material such as concrete, brick work or masonry;

the ultimate tensile strength of a ductile material such as steel. Stress, Breaking - the stress required to fracture a material whether by compression, tension, or

shear. Stress, Compressive - a stress which causes an elastic body to shorten in the direction of the

applied force. Stress, Compressive - one that resists a force tending to crush a body. Stress, Cooling - stress resulting from uneven contraction during cooling of metals and ceramics

due to uneven temperature distribution. Stress, Damaging - the minimum unit stress for a given material and use that will cause damage

to the member and make it unfit for its expected length of service. Stress, Design - the permissible maximum stress to which a machine part or structural member

may be subjected, which is large enough to prevent failure in case the loads exceed expected values, or other uncertainties turn out unfavorably.

Stress, Flow - the stress along one axis at a given valve of strain that is required to produce plastic deformation.

Stress, Fluid - stress associated with plastic deformation in a solid metal. Stress, Fracture - the minimum tensile stress that will cause fracture; also known as Fracture

Strength. Stress, Impact - force per unit area imposed on a material by a suddenly applied force. Stress, Inelastic - a force acting on a solid which produces a deformation such that the original

shape and size of the solid are not restored after removal of the force. Stress, Internal - Stress, Internal - a stress system within a solid that is not dependent on external forces; also

known as Residual Stress. Stress, Internal - residual stress in a material due to the differential effects of heating, cooling or

working operation, or to constitutional (e.g. phase) changes in a solid. To satisfy equilibrium, the net force on the body due to internal stresses must equal zero.

Stress, Limiting Creep - a somewhat loose term which is used to denote the maximum stress at which a material will not creep by more than a certain amount within the working life of the part. It also finds use in some short-time creep tests, as for example, the Hatfield Time Yield.

Stress, Limiting Range of - Stress, Limiting Range of - refers to the greatest range of stress that a metal is able to withstand

for an indefinite number of cycles without failure. If exceeded, the metal fractures after a certain number of cycles, which decreases as the range of stress increases. When the mean stress is zero, half this range is the fatigue limit.

Stress, Limiting Range of - the greatest range of stress about a mean stress of zero that a metal can withstand for an indefinite number of cycles without failure. The fatigue limit is half this range; also called Endurance Range.

Stress, Normal - it is on a section. It is the stress that acts in a direction perpendicular to section considered.

Stress, Operating - the stress to which a structural unit is subjected in service. Stress, Plane - a state of stress in which two of the principal stresses are always parallel to a

given plane and are constant in the normal direction. Stress, Pre - to apply a force to a structure to condition it to withstand its working load more

effectively or with less deflection. Stress, Primary - a normal or shear stress component in a solid material which results from an

imposed loading and which is under a condition of equilibrium and is not self-limiting.

Stress, Principal - a stress occurring at right angles to a principal plane of stress.

Stress, Principal Axis of - one of the three mutually perpendicular axes of a body that are perpendicular to the principal planes of stress; also known as Stress Axis.

Stress, Principal Plane of - for a point in an elastic body, a plane at that point across which the shearing stress vanishes.

Stress, Proof - Stress, Proof - 1) the stress that causes a specified amount of permanent deformation in a

material; 2) a specified stress to be applied to a member or structure in order to assess its ability to support service loads.

Stress, Proof - in metals which do not exhibit a sudden yield point, the stress which is required to produce a certain amount of extension.

Stress, Proof - refers to the stress in a metal at which a permanent elongation gets produced equal to a specified percentage of the original gauge length.

Stress, Residual - Stress, Residual - refers to the stress which exists in an elastic solid body in the absence of, or in

addition to, stresses caused by an external load. Such residual stress may be due to: a) deformation, caused by cold working, as in drawing or stamping, b) change in the specific volume due to thermal expansion, a phase change or magnetostriction, or c) by the joining together of structural parts by force, such as welding.

Stress, Residual - stress present in a component free of external forces or thermal gradients. Stress, Shear - see Stress, Shearing Stress, Shearing - Stress, Shearing - a force causing two contacting parts or layers to slide upon each other, in

opposite directions parallel to the plane of their contact. Stress, Shearing - a stress in which the material on one side of a surface pushes on the material

on the other side of the surface with a force which is parallel to the surface; also known as Shear Stress and Tangential Stress.

Stress, Shearing - one that resists a force tending to make one layer of a body slide across another layer.

Stress, State of - a complete description, including the six components of stress, of a homogenously stressed volume

Stress, Surge - the physical stress on process equipment or systems resulting from a sudden surge in fluid (gas or liquid) flow rate or pressure.

Stress, Tangential - see Stress, Shearing Stress, Tensile - Stress, Tensile - one that resists a force tending to pull a body apart. Stress, Tensile - stress developed by a material bearing a tensile load. Stress, Tensile - stress produced when external forces tend to stretch a body or pull particles

away from one another. Stress, Tensile - the net tensile component of all combined stresses: axial or longitudinal,

circumferential or “hoop”, and residual. Stress, Torsional - one that resists forces tending to twist a body. Stress, Total - the resultant internal force that changes the size or shape of a body acted on by

external forces. Stress, Ultimate - Stress, Ultimate - it is ratio of the maximum load that a specimen sustains to its original area of

the cross-section. Stress, Ultimate - the stress at which failure occurs. Stress, Ultimate Tensile - Stress, Ultimate Tensile - refers to the load at which a test piece breaks divided by its original

area. Stress, Ultimate Tensile - the maximum load that a specimen of a material can sustain under

tension divided by the original cross sectional area of the specimen. Stress, Ultimate Tensile - the ratio of the highest load applied to a piece of metal during a tensile

test divided by the original cross-sectional area; also called Tenacity. Stress, Uniaxial - a state of stress in which two of the three principal stresses are zero. Stress, Unit - Stress, Unit - the load per unit of area.

Stress, Unit - the stress per unit area. Stress, Working - Stress, Working - the safe stress for a structure or mechanism, based on experience and distinct

from any proof stress. Stress, Working - the stress which is considered to be a safe maximum for a particular material

under ordinary conditions. Stress, Yield - Stress, Yield - the lowest stress at which extension of the tensile test piece increases without

increase in load. Stress, Yield - the stress at the onset of plastic deformation, determined from the yield point or

from a defined amount plastic strain called the proof stress. Stressing, Under - repeatedly stressing a part at a level below the fatigue limit or below the

maximum service stress to improve fatigue properties. Stretch Forming - it is a method of producing contours in sheet metal and of bending previously

rolled formed sections. Strip - Strip - thin, flat steel that resembles hot-rolled sheet, but it is normally narrower (up to 12 inches

wide) and produced to more closely controlled thicknesses. Strip also may be cut from steel sheet by a slitting machine; see Sheet Steel.

Strip - to break or otherwise damage the threads of a nut or bolt. Stroke - Stroke - see Travel Stroke - 1) a single operation of a valve from the fully open position to the fully closed position or

vice-versa; 2) one whole motion of a piston (on an actuator) in either direction. Stroke - the linear extent of movement of a reciprocating mechanical part; see also Travel. Stroke Cycle - travel of the closure member from its closed position to the rated travel opening

and return to the closed position. Stroke Time - the time required for one half a stroke cycle at specified conditions. Structural Transformations in Steel (during cooling) - a steel containing 0.8% carbon is

known as eutectoid steel. A hypoeutectoid steel contains less than 0.8% carbon, while a hypereutectoid steel contains more than 0.8% carbon. When a steel containing 0.8% carbon is cooled from austenitic temperature to lower temperatures, it undergoes transformation into pearlite.

Stub Shafts - two separate shafts, one or both of which transmits movement to the disc; also called Trunnions.

Stud - a bolt, threaded on both ends, often used in bolting together bodies and bonnets or bodies and closures.

Stud / Stud Bolt - A stud bolt is used to hold two or more pieces together. It is threaded the full length (T.F.L.) and fits through bolt holes which are not tapped. A hex nut is used on both ends. A stud is similar to stud bolt except it threads into a tapped hole and a hex nut is used on one end only.

Stud Bolt - Stud Bolt - a small, thick round bar of metal, with a screw thread along its entire body, used with

a nut on both ends to fasten things together; compare with Machine Bolt. Stud Welding - a means of attaching a short piece of round metal rod, usually threaded, onto

another metal surface by using a gun-like device which holds the stud perpendicular to, and against, the surface. By a timing device, an intense electrical current flows from the stud to the base metal and within a specially processed tip, fusion takes place to join the two.

Studded Flange Connections - flanges end and outlet connections in which thread anchored studs screwed into tapped holes replace the holes for bolt studs.

Stuffing - Stuffing - a method of sealing the mechanical joint between two metal surfaces; packing

(stuffing) material is inserted within the seal area container (the stuffing or packing box), and compressed to a liquid-proof seal by a threaded packing ring follower; also known as Packing.

Stuffing - the purpose of stuffing is to seal off the space around a rotating shaft where it passes

through a casing. Stuffing Box - Stuffing Box - ( applicable only to adjustable forms of stem or shaft sealing ). the part of the body

or cover which provides an annular space around the shaft or stem to contain the gland packing.

Stuffing Box - a cavity and closure with manual adjustment for a sealing device. Stuffing Box - a cavity around a rod or shaft that penetrates a pump casing, valve body or other

portion of a pressure boundary which can be filled with packing material and compressed to form a leak tight seal while still permitting axial or rotary motion of the shaft.

Stuffing Box - a cylindrical recess which is tightly filled with some form of pacing, to prevent leakage of stem from an engine or of water from a pump.

Stuffing Box - a packed, pressure-tight joint for a rod that moves through a hole, to reduce or eliminate fluid leakage.

Stuffing Box - a part of the valve bonnet which provides an annular space around the stem to contain the gland and the gland packing.

Stuffing Box - an annular space through which a machinery part moves, and in which packing is compressed by a gland to make a pressure-tight joint, such as the rod of a pump or the stem of a valve.

Stuffing Box - gland box Stuffing Box - Packing Chamber Stuffing Box - the annular (ring shaped) chamber provided around a valve stem in a sealing

system into which deformable packing is placed; also called Packing Chamber. Stuffing Box - the part of the body or cover which provides an annular space around the shank or

stem to contain the gland and the gland packing. Stuffing Box - the part of the bonnet which provides an annular space around the stem to contain

the gland and the gland packing. Stuffing Box - the part of the bonnet, or separate component attached to it, which provides an

annular space around the stem or spindle to contain the gland and the gland packing.

Stuffing Box - the space in the bonnet of a valve that holds the packing used to seal against external leakage along the stem; also called a Packing Chamber.

Stuffing Box - used with packing glands to reduce leakage of a liquid from a machine at the point where the shaft passes through the casing wall.

Stuffing Box Bolting - comprises bolts, stud-bolts, studs, set screws and nuts used to secure the stuffing box, where separate, to the body or bonnet. This bolting may be extended to form gland bolting.

Stuffing Box Boss - a boss on the side of the stuffing box to provide sufficient metal to permit tapping.

Stuffing Box Gasket - a component for effecting a fluid-tight joint between the body or bonnet and the stuffing box.

Stuffing Box Tapping - a tapping on the side of the stuffing box leading to the space provided by the lantern ring.

Stuffing Nut - a nut for adjusting a stuffing box. STYB - Strainer Y-Type Subassembly - Subassembly - a structural unit, which, though manufactured separately, was designed for

incorporation with other parts in the final assembly of a finished product. Subassembly - any parts of an assembly which can be treated as a separate item. Sublimation - the direct conversion of a substance from solid state to vapor state without

passing through a transitory liquid state. The vapor, upon recondensing, reforms into the solid state with no intervening liquid phase.

Submerged Arc Welding - Submerged Arc Welding - an arc welding process in which the arc is produced between the bare

metal electrode and the workpiece under a blanket or granular fusible material. Submerged Arc Welding - an electric arc welding process in which coalescence is produced by

striking an arc between a bare metal electrode and the workpiece. In this process

the electrode is a continuously fed wire and shielding takes place under a layer of protective powder known as flux. Flux powder is fed continuously by mechanical devices ahead of the welding portion and the arc is submerged under the powder. This process is very suitable for production of quality butt welds in thick plates. The pieces to be joined are properly cleaned, shaped and placed in position. The trigger is pulled and flux starts depositing on the joint to be welded. The flux flows on the weld through a flux feeding tube. The electrode wire is brought near the workpiece underneath the flux and the arc is struck. The heat generated by the arc brings the metal and the flux to the molten state. Since flux is lighter, it forms a covering and floats on the molten pool of metal. Flux protects the metal from formation of oxides and nitrites of metal by not allowing the air to come in contact with the metal. The welding bead advances at predetermined speed and whole of flux in hopper unit slides ahead of the arc. The process is continued till the whole surface is welded. Unused flux is collected and slag is removed after completion and cooling of weld.

Submerged Arc Welding - an electric arc welding process in which the arc between a bare wire welding electrode and workpiece is completely covered by granular flux during welding.

Submerged Zone - the region below the splash zone including seawater, sea bottom and buried zones.

Subscale - subsurface oxides formed by reaction of a metal with oxygen that diffuses into the interior of the section rather than combining with metal in the surface layer.

Subsea Valve - Subsea Valve - a valve which is designed for use in sea water. For example, installed in a

pipeline on the sea bed. Subsea Valve - a valve which is suitable for operation submerged is sea water, usually in a

pipeline on the seabed. Subsonic Inlet - an entrance or orifice for the admission of fluid flowing at speeds less than the

speed of sound in the fluid. Subsonic Nozzle - a nozzle through which a fluid flows at speed less than the speed of sound in

the fluid. Substation - an intermediate compression station to repressure a fluid being transported by

pipeline over a long distance. Substrate - Substrate - a surface underlying a coating such as paint, porcelain enamel or electroplate. Substrate - basic surface on which a material adheres, for example, paint or laminate. Substrate - raw material used as an input for steel processing; for example, hot-rolled steel is the

substrate for cold-rolling operations. Substrate - the surface to be painted or coated Subsystem - a major part of a system which itself has the characteristics of a system, usually

consisting of several components. Suction Lift - the head, in feet, that a pump must provide on the inlet side to raise the liquid from

the supply well to the level of the pump; also known as Suction Head. Suction Valve - a non-return check valve, which is fitted on a suction pipe. Sulphide - a compound of sulphur with another element. Sulphur (S) - Sulphur (S) - a pale yellow non-metallic element that burns with a blue flame and a suffocating

smell. Sulphur (S) - in steels, sulphur is either present in the form of MnS or FeS. Ferrous sulphide

forms brittle, low melting yellowish brown films around the solid steel crystals and causes the metal to split on forging and is thus undesirable. Manganese sulphide is slightly soluble in iron and collects into large globules irregularly distributed through the steel. It is plastic at high temperatures, being elongated into threads by rolling without seriously impairing the properties of the material. In tool steels, sulphur should not exceed 0.035%. The manganese should be about five times that theoretically required to combine with the sulphur present.

Sulphur (S) - increased sulphur content in steel lowers transverse ductility and notched impact toughness, but has only a slight effect on longitudinal mechanical properties.

Weldability decreases with increasing sulphur. Sulphur is added, however; to improve machinability.

Sulphur Dioxide (SO2) - a strong and sharp smelling, colorless gas produced in the burning of hydrocarbons and other sulphur-containing compounds. It is used in metal refining, in the manufacture of sulphuric acid, and as a solvent.

Sulphuric Acid (H2SO4) - a colorless, odorless, dense, oily liquid that is highly corrosive and slightly acidic when diluted with water. Dilute sulphuric acid is used for electroplating.

Sun Checking - surface cracks, checks, or crazing caused by exposure to direct or indirect sunlight.

Super Cobalt Drill - a drill made of 8% cobalt high speed steel; used for drilling work-hardened stainless steels, silicon chrome, and certain chrome-nickel alloy steels.

Super Cooling - cooling of a substance below the temperature at which a change of state would ordinarily take place without such a change of state occurring, for example, the cooling of a liquid below its freezing taking place; this results in a metastable state.

Supercritical - property of a gas which is above its critical pressure and temperature. Supercritical Fluid - a fluid at a temperature and pressure above its critical point. Superheat - Superheat - 1) to heat a liquid under pressure above its boiling point without vaporizing it; 2) to

heat (steam not in contact with water) beyond its saturation point, so that a drop in temperature will not cause reconversion to water.

Superheat - sensible heat in a gas above the amount needed to maintain the gas phase. Superheat - to heat a substance above the temperature at which a change of state would

ordinarily take place without such a change of state occurring, for example, the heating of a liquid above its boiling point without boiling taking place; this results in a metastable state.

Superheated Vapor - a vapor that has been heated above its boiling point. Superstructure - the part of a valve located above the body. It may include the stem, handle,

bonnet and other parts. Supply Control - the process by which an item of supply is controlled within the supply system,

including requisitioning receipt, storage, stock control, shipment, disposition, identification, and accounting.

Supply Line - a line that conveys fluid from the reservoir to the pump. Support Legs - Support Legs - a metal structure attached to a valve body to provide a stable footing when the

valve is to be set on a fixed base. Support Ribs - see Support Legs Support Ribs or Legs - a metal structure attached to a valve body to provide a stable footing

when the valve is to be set on a fixed base. Surface - the outer part (skin with a thickness of zero) of a body; can apply to structures, to

micrometer-sized particles, or to extended-surface zeolites. Surface Finish - Surface Finish - casting produced in sand moulds must possess good surface finish. Surface Finish - the surface roughness of a component after final treatment, measured by a

surface profile. Surface Gauge - 1) a scribing tool in an adjustable stand, used to mark off castings and to test

the flatness of surfaces; 2) a gauge for determining the distances of points on a surface from a reference plane.

Surface Hardening - Surface Hardening - any of several processes for producing a surface layer on steel that is

harder and more wear resistant than the softer, tougher core; the process usually involves some kind of heat treatment, and may or may not involve changing the chemical composition of the surface layer.

Surface Hardening - see Case Hardening Surface Roughness - the closely spaced unevenness of a solid surface (pits and projections)

that results in friction for solid-solid movement or for fluid flow across the solid surface.

Surface Safety Valve (SSV) - an automatic wellhead valve which closes upon loss of power. Surface Treating - Surface Treating - any method of treating a material (metal, polymer, or wood) so as to alter the

surface, rendering it receptive to inks, paints, lacquers, adhesives, and various other treatments, or resistant or weather or chemical attack.

Surface Treating - any of several processes for altering properties of a metal surface, making it more receptive to ink, paint, electroplating, adhesives or other coatings, or making it more resistant to weathering or chemical attack.

Surfacing - see Weld Overlay Surge - Surge - 1) an upheaval of fluid in a processing system, frequently causing a carryover (puking) of

liquid through the vapor lines; 2) the peak system pressure. Surge - a momentary rise of pressure in a circuit. SUS - Seat Up Stream SV - Solenoid Valve SW - Socket Weld SWA - 1) Single–Wire Armored; 2) Steel Wire Armoring SWAA - Spray Water Assembly Type 1 SWAB - Spray Water Assembly Type 2 Swab Valve - see Crown Valve SWAC - Spray Water Assembly Type 3 SWAD - Spray Water Assembly Type 4 Swage - Swage - a tool or die that is used in the working, bending and shaping of cold metal. Swage - a tool used with a hammer, for shaping metal to a round or hexagon finish. Swaging - Swaging - a forging operation consisting of applying compressive or impact forces on the metal

below the recrystallization temperature. It causes the metal to flow in the predetermined shape according to the design of the dyes; also known as Cold Forging.

Swaging - it is a metal-forming process where in a series of impact blows transferred on dies to the solid or tubular work cause a change in cross-section or geometric shape.

Swarf - chips, shavings, and other fine particles removed from the work piece by grinding tools. SWB - 1) Single–Wire Braided; 2) Steel Wire Braiding SWE - Socket Weld End Sweet Crude - crude petroleum containing very little sulphur. Sweet Gas - natural gas containing no hydrogen sulfide or mercaptans. Sweetening - improvement of a petroleum-product color and odor by converting sulphur

compounds into disulfides with sodium plumbite (doctor treating), or by removing them by contacting the petroleum steam with alkalis or other sweetening agents.

Swell - Swell - in castings, an enlargement of the mold cavity by localized metal pressure. It is caused

due to a) insufficient ramming, b) low mold strength, c) inadequately supported molds, and d) insufficient weighting of the mold.

Swell - the increased volume of a specimen caused by immersion in a fluid (usually a liquid). SWG - an abbreviation for Standard Wire Gauge, defining the diameters and breaking strains of

steel wire. SWGBP - Swage (BLE/PSE) SWGBT - Swage (BLE/TSE) SWGP - Swage (PBE) SWGT - Swage (TBE) Swing Check Valve - Swing Check Valve - a check mechanism incorporating a disc which swings on a hinge. Swing Check Valve - a check valve design in which the flow control element rotates about an axis

that is perpendicular to the fluid path and is outside the fluid path and the flow control element; compare with Tilting Disc Check Valve.

Swing Check Valve - a check valve in which the closure element is a hinged clapper which swings or rotates about a supporting shaft.

Swing Check Valve - a type of check valve in which the non-return mechanism incorporates a disc which swings on a hinge.

Swing Check Valve - this non-return valve has a hinged disk as the closing element. Switch - a device for making, breaking, or charging the connections in an electrical circuit. Swivel - Swivel - a coupling between two parts enabling one to revolve without turning the other. A swivel

nut with a swivel nut pin can be used to hold the plug disc in a globe valve. Swivel - a part that oscillates freely on a headed bolt or pin. Swivel Coupling - a coupling that gives complete rotary freedom to a deflecting wedge-setting

assembly. SWOP - Single Well Oil Pressure SWP - Steam Working Pressure SWT - Socket Weld equal Tee SXU - Socket weld X screwed SY - Pneumatic pilot valve Symmetry - exact similarity between two parts or halves, as if one were the mirror image of the

other. Synchronize - to make two or more events or operations occur at the proper time with respect to

each other. Synchronous Machine - an alternating current machine in which the frequency of the generated

voltage and speed of the machine are in a constant ratio. Synthetic Material - a complex chemical compound that is artificially formed by the combining of

two or more simpler compounds or elements. Synthetic Sands - sands deficient in clay which have been blended with bentonite or other clay-

like material to make them suitable for molding. Systeme Internationale d'Unites (SI) - the current International System of Units

T - 1) Thickness; 2) Tee T & C - Threaded and Coupled T Slot - a recessed slot, in the form of an inverted T, in the table of a machine tool, to receive the

square head of a T-slot bolt. TAC - Technical Assistance Contract Tack - the stickiness of a paint or varnish film during the drying period. Oil paints and some

varnishes may maintain a certain degree of tack for some weeks after they are basically considered dry.

Tack Weld - Tack Weld - 1) any small, isolated arc weld especially one that does not bear load but rather

merely holds two pieces in a fixed relationship; 2) a weld joint made by arc welding at small, isolated points along a seam.

Tack Weld - a small, temporary weld to hold a member in position until permanent connections can be made.

Tack Weld - a weld made to hold parts in a proper position before the actual welding. Tack Weld - a weld that is made to hold parts of a weldment in proper alignment until the final

welds are made. After preparation, accurate alignment of plate edges is needed. It is necessary when the gap is uniform throughout the joint. If the job is not held in fixture, the practice of tack welding is used to hold the pieces in position to avoid their movement during welding.

Tack Weld - making short, provisional welds along a joint to hold it in position and prevent distortion during a subsequent continuous welding.

Taconite - a natural mineral containing less than 30% iron. It is the primary ore used in blast furnaces. Domestic supplies of iron-rich ores (greater than 50% iron) were largely depleted in the 1940s, so integrated steel companies now process the lower-grade taconite to make it useful.

Tailored Blanks - a section of sheet or strip that is cut-to-length and trimmed to match specifications for the manufacturer's stamping design for a particular part. Because excess steel is cut away (to save shipping costs), all that remains for the stamper is to impart the three-dimensional shape with a die press; see also Blanking.

Tandem Mill - a type of cold-rolling mill. The tandem mill imparts greater strength, a uniform and smoother surface, and reduced thickness to the steel sheet. Unlike the original single-stand mills, a tandem mill rolls steel through a series of rolls (generally three to five in a row) to achieve a desired thickness and surface quality.

Tank - a container for the storage of fluid in a fluid power system. Tank Valve - a valve arranged for fitting at the bottom of a tank or process vessel. Tank Valve, Flush Fitting - a valve arranged for flush fitting at the bottom of a tank or process

vessel. Closure is effected with a disc and seating located in the tank-connecting flange.

Tantalum - tantalum is used in some special steels to give increased resistance to scaling at high temperatures.

Tap - Tap - 1) a screwed plug of accurate thread, form and size, on which cutting edges are formed

along longitudinal grooves; 2) to cut an internal thread. Tap - 1) a threaded plug, where the threads are of accurate form and dimensions, and have

cutting edges that form internal threads in a hole as the plug is screwed into the hole; 2) a small hole in the wall of a pipe or process vessel, usually threaded, where an instrument, control device or sampling device is attached.

Tap - a small, threaded hole drilled into a pipe or process vessel, used as connection points for sampling devices, instruments, or controls.

Tap - internally threaded; to cut a thread in something to accept a screw. Tap - to form an internal screw thread in a hole or other part by means of a tap. Tap Bolt - a bolt with a head that can be screwed into a hole and held in place without a nut;

also known as Tap Screw. Tap Drill - a drill used to make a hole of a precise size for tapping. Tap Screw - see Tap Bolt Taper Rolling Bearing - a roller bearing capable of sustaining end thrust by means of tapered

rollers and coned races. Taper Tap - a threaded cone-shaped tool for cutting internal screw threads. Taper Washer - a type of washer designed to be used underneath nuts with tapered flanges to

enable the bolt assembly to fit properly when tightened. Tapered Roller Bearing - a roller bearing having tapered rollers that run in conical races; it can

support both radial and thrust loads. Tappet - Tappet - a sliding bar between a cam and a push rod, which changes the circular motion of the

cam into the up and down motion of the rod. Tappet - an oscillating part such as a lever, operated by a cam or push rod, and used to tap or

push another machine element such as a valve. Tapping - the operation of running molten metal from a furnace into a ladle. Tapping Screw - see Self-tapping Screw Tarnish - discoloration of a finished surface by a thin film of corrosion products. TAS - Technical Audit and Safety Department TBA - To Be Advised TBE - Threaded Both Ends TE - Threaded End Tear Resistance - the resistance to growth of a cut or nick when tension is applied to the cut

specimen. Commonly expressed as pounds per inches thickness. Technical Specifications - a detailed description of the technical characteristics of an item or

system in sufficient detail to form the basis for design, development, production and, in some cases, operation.

Tee - a three-port fitting used to join one pipe at right angles to two other pipes. Tee Valve - a valve with an extra port on the system side. It is useful for roughing manifolds. TEEB - Equal Tee Butt-Weld Ends Teeming - Teeming - pouring molten metal into an ingot mold; most often used with reference to steel

production. Teeming - pouring; ingot molds are filled (teemed) by iron-bearing ladles. TEFC - Totally Enclosed Fan Cooled Teflon® - Teflon® - a non-metallic material used as valve trim. It is a thermoplastic also known as

tetrafluoroethylene (TFE), Virgin TFE, and PTFE (Poly-TFE). It is abrasion resistant, relatively soft but tough, and has a very low coefficient of friction. Glass fibers are added to Teflon to produce reinforced, or filled Teflon (RTFE).

Teflon® - a trademarked (DuPont) elastomer (tetrafluoroethylene) with good chemical resistance. It is used for seals, gaskets, O-rings, and recommended for temperatures up to 300°C. It is permeable to helium. It has no melting point, but turns into an amorphous jelly above 327°C. Above 400°C, it decomposes, releasing poisonous fluorine volatiles.

Teflon® - this is the brand name for a number of fluorinated polymers manufactured by E.I. DuPont de Nemours. Many valve manufacturers use this term illegally, when in fact their products are not Teflon® but generic PTFE, PFA etc.

Tefzel® - a non-metallic material used as valve trim. It is a thermoplastic also known as ETFE (ethylene-tetrafluoroethylene). It is tough, and has no known solvent below 390°Fahrenheit. It is used for butterfly valve seats and diaphragm valve linings.

Telescoping Valve - a valve, with sliding telescoping members, to regulate water flow in a pipe line with minimum disturbance to stream lines.

Temper - Temper - 1) in masonry construction, the moistening of mortar and remixing it to the proper

consistency to compensate for moisture lost between the time it is mixed and the time it is used; also called Retempering; 2) in nonferrous alloys (i.e., aluminum) an indication of the hardness and strength produced by mechanical or heat treatment.

Temper - 1) reheating a quench hardened or normalized ferrous alloy to a temperature below the transformation range (Ac) and then cooling at any desired rate; 2) a term used in conjunction with a qualifying adjective to designate the relative properties of a

particular metal or alloy induced by cold work or heat treatment, or both. Temper - 1) the relative hardness and strength of flat rolled steel or stainless steel that cannot be

further hardened by heat treatment; 2) the relative hardness and strength of nonferrous alloys, produced by mechanical or thermal treatment (or both) and characterized by a specific structure, range of mechanical properties or reduction of area during cold working; 3) in the production of casting molds, to moisten mold sand with water; 4) in the heat treatment of ferrous alloys, to reheat after hardening for the purpose of decreasing hardness and increasing toughness without undergoing a eutectoid phase change; 5) in tool steels, an imprecise shop term sometimes used to denote carbon content.

Temper - 1) to heat a metal or hardened alloy (such as steel) to a certain temperature and then allow it to cool slowly, in order to toughen it by reducing its hardness and making it less brittle; 2) the degree of hardness and elasticity in steel or other metal; 3) in heat treatment, reheating hardened steel or hardened cast iron to some temperature below the critical temperature for the purpose of decreasing the hardness and increasing the toughness. The process is also sometimes applied to normalized steel.

Temper - a heat-treating process for metals that generally follows quenching or normalizing. Usually it is done to increase toughness and ductility and is accompanied by decreases in strength and hardness.

Temper - a vague term describing the relative condition of the hardness and mechanical properties of a metal; for example, a solid solution alloy which can be extensively cold worked may exhibit a range of properties from its softest state when annealed to fully work hardened. This range is divided into hardness bands, referred to as tempers, e.g. quarter hard, half hard etc. A given temper can be achieved either by full annealing followed by careful work-hardening or by full work-hardening followed by careful annealing; the latter is referred to as temper annealing or back annealing.

Temper - decreasing the hardness of a metal by reheating the metal to a temperature below the critical range.

Temper - heating already hardened steel to a temperature lower than its own hardening temperature and then allowing it to slowly.

Temper - heating hardened ferrous alloys below the transformation temperature to reduce hardness and improve toughness.

Temper - the treatment given to already hardened steel in order to reduce brittleness and unequal stress developed as a result of hardening. Tempering reduces brittleness and hardness but improves tensile strength in steels. Tempering involves heating steels to much below the lower initial temperature and then cooling it slowly in tempering oils, air or liquid salt baths. The range of heating temperatures and the rate of cooling depends on the amount of hardness and brittleness to be removed. Heating to a higher temperature and then cooling at a slower rate produces a softening effect on steel as in the process of annealing. Plain carbon steels are generally heated to about 280° C for tempering. As a result of tempering steels,extremely hard martensite in hardened steels is partly transformed to softer constituents of pearlite and cementite and hence brittleness is reduced at the cost of hardness.

Temper Carbon - compact aggregates or nodules of graphite found in malleable iron as a result of heat treatment.

Temper Mill - a type of cold-rolling mill, usually with only one or two stands, that finishes cold-rolled, annealed sheet steel by improving the finish or texture to develop the required final mechanical properties. By changing the rolls of the temper mill, steel can be shipped with a shiny, dull or grooved surface.

Temperature Actuated Pressure Relief Valve - a pressure relief valve which operates when subjected to increased external or internal temperature.

Temperature Control Valve - a valve with actuating means operated by a temperature measuring device used to control the temperature level on a system.

Temperature Range - the maximum and minimum temperature limits within which a seal compound will function in a given application.

Tempilstick - a crayon made of a material having a sharp reaction at a specific temperature; in

use, a crayon sensitive to a specific temperature is used to mark the surface of a metal to be heated; confirmation that the intended temperature was reached or exceeded is indicated by a change in color of the mark.

Template - 1) a two-dimensional representation of a machine or other equipment used for building layout design; 2) a guide or a pattern used in manufacturing items; also spelled Templet.

Templet - see Template Temporary Storage - materials and equipment in transit at supply bases, construction sites or

storage yards for a period of 6 to 12 months. Temprite - this is a formulation of Corzan® CPVC that is used for injection molded valve bodies. Tenacity - the ability of a material to resist the effect of tensile forces without rupture. Mild steel,

wrought iron, cooper etc. are tenacious metal. Tender - 1) a formal offer; 2) to do work or supply goods for a stated amount of money and

within a stated period of time. Tenon - a tongue like projection from the end of a framing member which is made to fit into a

mortise. Tensile - able to be drawn out or stretched Tensile Bar - a molded, cast, or machined specimen of specified cross-sectional dimensions

used to determine the tensile properties of a material by use of a calibrated pull test; also known as Tensile Specimen and Test Specimen.

Tensile Specimen - Tensile Specimen - a bar, rod or wire of specified dimensions used in a tensile test; also known

as Tensile Bar; Test Specimen. Tensile Specimen - see Tensile Bar Tensile Strength - Tensile Strength - the maximum tensile stress which a material will develop. The tensile strength

is usually considered to be the load in pounds per square inch at which a test specimen ruptures.

Tensile Strength - (Maximum Stress). refers to the highest load applied in breaking a tensile test piece divided by the original cross-sectional area of the test piece.

Tensile Strength - 1) the resistance of a material to breaking under tension; 2) in tensile testing, the ratio of maximum load to original cross-sectional area (refer to ASTM A 370); also called Ultimate Strength; compare with Compressive Strength.

Tensile Strength - in tensile testing, the ratio of maximum load to original cross-sectional area; also called Ultimate Strength.

Tensile Strength - the force in pounds per square inch required to cause the rupture of a specimen of a rubber material.

Tensile Strength - the highest tensile stress that a material can withstand before failure or rupture occurs, the force being applied in a direction tending to elongate the material.

Tensile Strength - the maximum load per unit area that a material can withstand before fracture, usually computed as maximum load divided by original cross-sectional area of a standard specimen pulled to fracture in uniaxial tension.

Tensile Strength - the maximum stress a material subjected to a stretching load can withstand without tearing; also known as Hot Strength.

Tensile Strength - the resistance of a material to a pulleying stress; it is the property possessed by a material which enables it to withstand a force acting upon it with a tendency to break it by tearing. It is expressed in kg/cm of cross section.

Tensile Strength - this is the ability of a material to withstand tensile (stretching) loads without rupture occurring. The material is in tension.

Tensile Test - Tensile Test - a destructive test performed on a specially machined specimen taken from material

in its delivered condition to determine mechanical properties, such as tensile strength, yield strength, and percent elongation.

Tensile Test - a method of determining mechanical properties of a material by loading a machined, cast or molded specimen of specified cross sectional dimensions in uniaxial tension until it breaks; the test is used principally to determine tensile strength, yield strength, ductility and modulus of elasticity; also known as Pull Test.

Tensile Test - a test in which a specimen is subjected to increase longitudinal pulling stress until fracture occurs.

Tensile Test - a test in which specimens have been subjected to an increasing tensile load until they fracture. A stress-strain curve could be plotted and the limit of proportionality, proof stress, yield point, tensile strength, elongation and reduction of area determined.

Tensile Test - the tensile test is widely used for determining the strength and ductility of a material. The test involves loading a standard specimen axially. The load is increased at a constant rate mechanically or hydraulically. The specimen increases in length until it finally fractures. During the test the specimen is gripped at each end to ensure simple uneasily loading and freedom of bending. The extension is measured from the gauge length. The mid-portion of the specimen is reduced in diameter to ensure fracture occurs within the gauge length.

Tension - the condition of a string, wire, or rod that is stretched between two points. Tensometer - a portable machine that is used to measure the tensile strength and other

mechanical properties of materials. TEP - Total Equivalent Pressure TERB - Tee Reducing Butt Weld Ends Terne - sheet steel coated with a mixture of lead and tin. Terne principally is used in the

manufacture of gasoline tanks, although it also can be found in chemical containers, oil filters and television chassis.

Terneplate - a corrosion-resistive coating applied over steel, consisting of a mixture of lead and tin.

Terpolymer - a polymer consisting of three different monomers chemically combined. Tertiary Stage Creep - in the tertiary stage, the rate of extension accelerates and finally leads to

rupture. The use of alloys in this stage should be avoided, but the change from secondary to tertiary stage is not easy to determine. Yield strength is the practical measure of the stress necessary to start plastic deformation at room temperature. On the other hand, at high temperature, plastic deformation (creep) appears to occurs at all stresses. Careful measurements are required to determine the small rates of plastic deformation involved in creep. A special testing machine is used for measuring creep strength which is fitted with precision strain measuring devices. The relatively constant second stage creep is preceded by a brief first stage creep and it is followed eventually by accelerated creep and the final fracture in the third stage of creep.

TERV - Thermal Relief Valve Test - Test - a procedure in which the performance of a product is measured under various conditions. Test - a standard procedure for determining an attribute or performance characteristic of a

material, part, component, assembly or system; a test may be used to determine basic properties, verify a function or condition, establish a response characteristic or calibration, or provide information about operating behavior.

Test Bar - a bar-shaped coupon that is tested with or without subsequent preparation for the determination of physical or mechanical properties.

Test Coupon - specially designed casting, or portion thereof, that is used to provide a representative sample of the iron from which it was cast.

Test Lug - a sample produced as an appendage on a casting, that may be removed and tested to qualify the casting or the iron which it was produced.

Test Piece - Test Piece - a piece of material which is prepared in a suitable shape so that it can be tested in a

testing machine. Test Piece - an accurately made piece of material which is used for a tensile test, impact test or

other testing machine. Test Specimen - Test Specimen - a test object, suitably prepared from a sample, for evaluation of the chemical,

physical, mechanical, or metallurgical quality of the sample. Test Specimen - see Tensile Bar Testing Machine - a machine which is used for applying test loads to standard test pieces or to

structural members. Machines are available for carrying out tensile, compressive, impact and fatigue tests.

Tetrafluoroethylene - see Teflon TFE - Tetrafluoroethylene (Teflon) TFL - 1) Threaded Full Length; 2) Through Flow Line THD - Threaded Thermal Cracking - a petroleum refining process that decomposes, rearranges, or combines

hydrocarbon molecules by the application of heat, without the aid of catalysts. Thermal Equilibrium - the state reached when the temperature rises of the several parts of a

machine do not vary by more than a gradient of 2K per hour. Thermal Expansion - Thermal Expansion - an expansion caused by increase in temperature. May be linear or

volumetric. Thermal Expansion - change in pipe length due to a change in crude oil temperature. Thermal Expansion - the increase in volume of a substance due to temperature change. Thermal Fatigue - fatigue failure resulting from strains caused by expansion and contraction

during thermal cycling. Thermal Hysteresis - a phenomenon sometimes observed in the behavior of a temperature-

dependent property of a body; it is said to occur if the behavior of such a property is different when the body is heated through a given temperature range from when it is cooled through the same temperature range.

Thermal Relief - a valve or other device that is preset to open when pressure becomes excessive due to increased temperature of the system.

Thermal Relief Valve - a valve which operates as a safety valve to prevent a pre-determined pressure being exceeded due to thermal expansion of contained fluid.

Thermal Shocks - the heat of cast metal may cause rapid expansion of sand surface in a mold. As such, sand must possess low coefficient of thermal expansion and be capable of withstanding high temperatures.

Thermal Valve - a valve controlled by an element made of material that exhibits a significant change in properties in response to a change in temperature.

Thermit Welding - Thermit Welding - a fusion welding process in which a mixture of finely divided iron oxide and

aluminum particles is ignited, reducing the iron oxide and producing a molten ferrous alloy that is then cast in a mold built up around the joint to be welded.

Thermit Welding - a welding process carried out by the heat produced by the chemical burning of thermit mixtures. Thermit mixtures generally contain iron oxides, aluminum and alloying elements.

Thermit Welding - this comprises a group of thermo-chemical welding processes in which coalescence is produced by heating with superheated liquid metal that contains aluminum and metallic oxides. Thermit welding is based on casting and foundry practice. It consists of melting the metal by means of chemical reactions and pouring the metal into the joint. The mixture of aluminum and iron oxide is known as thermite mixture. The practical temperatures obtained by this process are of the order of 2500° C. Other elements are also added to the thermit mixture to adjust the chemical composition. The metal surfaces to be joined are cleaned thoroughly to get a strong weld. After cleaning, the parts to be welded are lined up with a space of 1.5 to 5mm between the ends. This space is provided between the joint for contraction of steel on cooling and shrinkage of the base metal during welding. A wax pattern to form the mold is prepared and placed in a container. It is then heated until it reaches its plastic stage. The wax is then shaped around the parts that are to be welded together. A molding box is then placed around the portion to be welded and a molding material is rammed into the box. The mold is provided with the requisite number of pouring gates and risers. The mold is preheated to remove the wax, which leaves a mold cavity of the exact shape of the weld. The parts to be welded are heated to the desired temperature to prevent chilling of the hot thermit metal. The thermit mixture is placed in the crucible. A low ignition point thermit in the form of a powder is placed on top of the thermit in the crucible. Reaction is initiated by contact with a hot rod. The ignition immediately starts in the

main thermit charge. The crucible is tapped and the metal is poured into the cavity to fill the mold. After some time the welding is complete. The mold is opened and the weld is finished. The heat necessary for welding is obtained from the chemical reaction of thermit mixture. As such no costly equipment is needed.

Thermite - Thermite - a mixture of aluminum powder and half an equivalent amount of iron oxide (or other

metals oxides) which gives out a large amount of heat on igniting with magnesium ribbon; the molten metal forms the medium for welding iron and steel (thermal welding).

Thermite - a mixture of finely powdered aluminum and iron oxide that produces a very high temperature on combustion; used in welding.

Thermite - a mixture used for thermit weldings. It consists mainly of iron oxide and aluminum with different alloying elements. Also spelled “Thermit”.

Thermocouple - Thermocouple - 1) a temperature measuring instrument that develops an electric voltage when

heated because of the combined thermoelectric effect due to dissimilar composition between two electrically connected conductors (usually wires) and to temperature difference between the connection (hot junction) and the other end of the conductors (cold junction); 2) two dissimilar wires joined together that generate a voltage proportional to temperature when their junction is heated.

Thermocouple - a temperature-sensitive device using the principle that two dissimilar metals in contact at different temperatures will generate an electric current such as for gas-fired water heaters, wall heaters, etc.

Thermocouple - device which generates electricity, using the principle that if two dissimilar metals are welded together and the junction is heated, a voltage will develop across open ends.

Thermoplastic - a substance (usually a synthetic resin) that can be repeatedly softened and hardened, without any significant change in its properties, by heating and cooling it. A thermoplastic substance becomes or remains soft and moldable when heated; compare with Thermosetting.

Thermoplastic / Thermoset - two basic types of plastic resins. Thermoplastics are resins that can be reground after molding; and molded again. Thermosets can be molded once only; they tend to be denser materials for special purposes. PVC is a thermoplastic. A PVC valve could conceivably be reground, then molded into a coffee mug. The resin used on a solenoid coil is a thermoset. A good analogy is paraffin wax vs. paraffin paste; both are petroleum products, but the wax can be melted and reformed while the lubricant cannot. Just as paraffin cannot be melted and reshaped indefinitely, no thermoplastic can be successfully reground and remolded indefinitely; eventually the molecular bond begins to break down and the plastic is no longer usable. In another analogy, thermosets are often compared to an egg; once the egg is hard boiled it can't be returned to a liquid and recooked as sunny side up.

Thermosetting - Thermosetting - a substance (usually a synthetic resin) that becomes permanently hard after a

single melting and molding; compare with Thermoplastic. Thermosetting - these are the materials that harden during heat as a result of polymerization.

Urea formaldehyde and phenoformaldehyde are the thermosetting materials used for core making in casting. These materials make the cores stick to core boxes. This difficulty is overcome by the addition of 0.25% kerosene oil to the core sands.

Thermostatic Control Valve - a valve fitted with a temperature measuring device and automatic actuator means. It is used to control the temperature of the environment.

Thinner - a volatile liquid added to ease application of paint. THK - Thickness THR - Threaded THRD - Threaded Thread - a continuous helical rib, as on a screw or pipe. Thread Contour - the shape of thread design as observed in a cross section along the major

axis, for example, square or round.

Thread Cutter - a tool used to cut screw threads on a pipe, screw, or bolt. Thread Gauge - a design gauge used to measure screw threads. Thread Plug Gauge - a thread gauge used to measure female screw threads. Thread Projector - a short-threaded ring to screw onto a piece or into a coupling to protect the

threads while the pipe is being handled or transported. Thread Rating - the maximum internal working pressure allowable for threaded pipe or tubing

joints; important for pressure systems, chemical process, and oil-well systems. Thread Ring Gauge - a thread gauge used to measure male screw threads. Thread Rolling - producing a screw thread by rolling between flat or cylindrical dies an alloy

sufficiently plastic to withstand the cold working forces without disintegrating. Threaded End - Threaded End - a valve end that has female pipe threads cut into it to allow for screwing in male

connecting pipe. Threaded End - valve end connections incorporating threads, either male or female. Threading Die - a die which may be solid, adjustable, or spring adjustable, or a self-opening die

head, used to produce an external thread on a part. Threading Machine - a tool used to cut or form threads inside or outside a cylinder or cone. Three Phase - Three Phase - operating by means of combination of three alternating current circuits which differ

in phases by one third of a cycle. Three Phase - referring to an electricity supply using three separate alternating components with

phases differing by one third of a cycle, or 120 electrical degrees. Three Way Ball - a closure member that is a spherical surface with one or more flow passages

through it. The passages may be round, contoured or otherwise modified to yield a desired flow characteristic.

Three Way Diverting Valves - A valve which has three openings (one inlet and two outlets). Fluid entering the inlet point can he diverted to either of the two outlet ports, in any proportion desired, by moving the valve stem. Valves designed for diverting service can usually be used in mixing applications.

Three Way Pilot Valve - a pilot valve used with single acting (spring-return) actuators. Three Way Valve - 1) a control valve with three end connections; 2) a ball valve with three end

connections that is used for switching flow between one common connection and the other two connections.

Threshold - the maximum tolerance of an elastomer to radiation dosage expressed as a total number of ergs per gram (or rads) beyond which the physical properties are significantly degraded. This is generally an arbitrary value, depending on function and environment.

Throat - the least thickness of a weld, the calculation of its strength being based on the thickness at the throat.

Throat of a Weld - the place of least cross sectional area of a weld. In a fillet weld, this is the plane formed by an angle bisecting the corner angle.

Throttle - see Throttle Valve Throttle Valve - Throttle Valve - a chocking device to regulate flow of a liquid, for example, in a pipeline, to an

engine to turbine, from a pump or compressor; also known as Throttle. Throttle Valve - a device for regulating flow of a fluid by alternatively opening up or closing down

a restriction in a passage or inlet. Throttling - Throttling - control by means of intermediate steps between full on and full off. Throttling - modulating control as opposed to On/Off control. Throttling - reducing the pressure of a fluid by causing it to pass through minute or tortuous

passages. Throttling - the actions to regulate fluid flow through a valve by restricting its orifice opening; see

also Modulating. Throttling - the intentional restriction of flow by partially closing or opening a valve. Throttling - the process of reducing the pressure of a fluid by causing it to pass through minute or

tortuous passages so that no kinetic energy is developed and the total heat remains

constant. Throttling - the process of regulating the rate of fluid flow in a pipeline by moving the flow control

element of a valve. Throttling - the regulation of flow through a valve or other device. Through Shaft - a shaft extending completely through one disc; also called Spindle. Throw - Throw - the maximum diameter of the circle moved by a rotary part. Throw - the motion of a moving part driven by a cam, eccentric wheel, limit switch, etc. Throw - the total travel of a crank or similar element, being twice the radius of eccentricity;

sometimes half this distance is called the throw. Thrust - Thrust - a force exerted on an object which causes a linear movement. Thrust - a strong continuous pressure that one part of an object exerts against another. Thrust - generically, the force any body exerts on another body - both can be stationary, both can

be in motion, or one can be stationary and the other in motion. Thrust - the net force applied to a part in a particular direction; for example, on the end of a valve

stem. Thrust Bearing - Thrust Bearing - a bearing designed primarily for thrust loads. Thrust Bearing - a bearing on a shaft for taking an axial load (thrust) such as a ball-bearing with

lateral races, a Michell bearing or a plain bearing pad; also called Thrust Block. Thrust Bearing - a bearing that prevents the lengthwise movement of a rotating shaft by

counteracting the axial thrust of the shaft. The simplest types of this bearing may be made by providing collars on shafts bearing against flat rings of the journal type bearings. Thrust bearings may also be made in ball or roller construction for small and moderately heavy loads.

Thrust Bearing - a bearing that supports axial load on a shaft and prevents the shaft from moving in an axial direction.

Thrust Bearing - a bearing to take end thrust which is caused by forces acting along the line of the valve shaft (s); also called Thrust Collar.

Thrust Bearing - a bearing which sustains axial loads and prevents axial movement of a loadedshaft.

Thrust Bearing - ball or roller bearing for axial loads Thrust Bushing - used between the shaft collar and the body or bonnet of a valve to reduce

friction and wear when the shaft is turned. Thrust Collar - a collar on a shaft or spindle which transmits thrust bearing. Thrust Face - Thrust Face - face of thrust bearing against which housing or shaft shoulder pushes. Thrust Faces - faces which are acted upon by end thrust. Thrust Load - a load or pressure parallel to or in the direction of a shaft. Thrust Washer - a washer, normally on the end of the non-driven shaft, which enables end

thrust to be transmitted to thrust bearings; also called Thrust Disc, or Thrust Pad. Ti - Titanium TICO - Temperature Instrument Connections on Piping TIG Welding - TIG Welding - see Gas Tungsten Arc Welding TIG Welding - welding using a tungsten filler rod while the weld is surrounded by a continuous

flow of an inert gas. Tight - the absence of leaks in a pressure system. Tight Fit - a fit between mating parts with slight negative allowance, requiring light to moderate

force to assemble. Tight Shut Off - A valve having tight shutoff will have virtually no flow or leakage in its closed

position. Generally speaking, only single-seated valves have tight shutoff. Double-seated valves may be expected to have a leakage of two to five percent while in closed position.

Tight Shut Off Service - a valve primarily intended for isolation purposes, and which does not

leak in the closed position. Tilt Hammer - a heavy pivoted hammer used in forging, raised mechanically and allowed to drop

on the metal being worked. Tilting Disc Check Valve - a check valve design in which the flow control element rotates about

an axis that is perpendicular to the fluid path and is in the fluid path and passes through the flow control element; compare with Swing Check Valve.

Tin (Sn) - a soft, silvery-white metallic element used as a component of various alloys such as bronze and solder.

Tin / Chrome Plating - a plating process in which the molecules from the positively charged tin or chromium anode attach to the negatively charged sheet steel. The thickness of the coating is readily controlled through regulation of the voltage and speed of the sheet through the plating area.

Tin Free Steel - chromium-coated steel. Tin-free steel is easier to recycle because tin will contaminate scrap steel in even small concentrations.

TIR - Total Indicator Reading Titanium (Ti) - Titanium (Ti) - a hard, silvery-gray metallic element used to make strong, light, corrosion

resistant alloys. Titanium (Ti) - titanium fixes carbon in inert particles. It reduces martensitic hardness in

chromium steels. Titanium Alloys - titanium alloys are developed for useful strength and corrosion resistance at

temperature range between –230° Celsius and 540° Celsius. TLD - Thermoluminescent Dosimeter TMCP - Thermo-Mechanical Control Process Toe - the junction between the face of a weld and the adjacent base metal. Toe Crack - a crack in the weldment that runs into the base metal from the toe of a weld. TOL - Threadolet Tolerance (Tol) - an acceptable range of variation of some dimension. Tolerance (Tol) - an allowable amount of variation in the dimensions of a machine or part. Tolerance (Tol) - the maximum permissible variation in size of the part. Tolerance (Tol) - the permissible variations in the dimensions of machine parts. Tolerance (Tol) - the range between the permissible maximum and minimum limits of a size of a

work piece, or of distance between features (e.g. hole centers) on a workpiece. Tolerance (Tol) - Tolerance (Tol) - 1) permissible variation in the dimension of a part; 2) permissible deviation

from a specified value; may be expressed in measurement units or percent. Tolerance Limits - the extreme values (upper and lower) that are permitted by the tolerance. Ton - unit of measure for weight Ton, Gross - 2,240 pounds Ton, Long (Net) - 2,240 pounds Ton, Metric - 1,000 kilograms. 2,204.6 pounds or 1.102 short tons. Ton, Short (Net) - 2,000 pounds. Normal unit of statistical raw material input and steel output in

the United States. Tonne - a metric unit of weight equal to 2,205 pounds or 1.1 English tons. Tool and Die Steels - steels used for making tools and dies. Tool Steels - steels that are hardened for the use in the manufacture of tools and dies. Tooth - one of the shaped projections on the rim or face of a gear. Top and Bottom Guided - a type of valve design in which the plug is aligned by guides in the

valve body or in the bonnet and bottom flange. Top Entry Ball Valve - a ball valve in which there is access for means of assembly from that part

of the valve body incorporating the stem. Top Entry Check Valve - Top Entry Check Valve - a valve that can regulated the direction of the flow of fluid in one

direction. It can be checked for maintenance purposes by unscrewing the top. Top Entry Check Valve - with this sort of check valve the valve doesn’t have to be removed from

its position in order to be checked.

Topping - the distillation of crude petroleum to remove the light fractions only; the unrefined distillate is called Tops.

Topping Unit - a mini-refinery that draws crude off the line and produces turbine fuel to power the station.

Topworks - a nonstandard term for control valve actuator. Torch - a welding blowpipe (torch) or cutting blowpipe (torch). Torch Brazing - a brazing process using a non-ferrous material to join metallic pieces with the

help of a torch. Toroidal - doughnut-shaped Toroidal Sealing Ring - an “O”- ring Torque - Torque - a force or combination of forces that produces or tends to produce a twisting or rotary

motion. Torque - a measure of the tendency of a force to cause rotation, loosely defined as force

multiplied by distance; more exactly, equal to the force multiplied by the perpendicular distance between the line of action of the force and the center of rotation.

Torque - a rotary force, such as that applied by a rotating shaft at any point on its axis of rotation. Torque - a turning or twisting force Torque - a twisting force which tends to cause rotation about some point. Torque - the rotational force imposed on or through a shaft, usually expressed in foot-pounds. Torque - the turning force of a shaft Torque Wrench - Torque Wrench - 1) a hand or power tool that can be adjusted to deliver a preset rotary force to a

nut or bolt; 2) a wrench that can measure the torque required to start rotary motion when tightening or loosening a bolt.

Torque Wrench - 1) a hand or power tool used to turn a nut on a bolt that can be adjusted to deliver a predetermined amount of force to the bolt when tightening the nut; 2) a wrench that measures torque while being turned.

Torr - the unit of pressure used in vacuum measurement. It is equal to 1/760 of a standard atmosphere, and for all practical purposes is equivalent to one millimeter of mercury (mm Hg). Example: 25 mm Hg=254 torr 1 x 10-3 mm Hg=10-3 torr (millitorr) 1 x 10-6 mm Hg=10-6 torr (microtorr)

Torsiometer - an instrument consisting of angular scales mounted around a rotating shaft to determine the amount of twist in the loaded shaft, and thereby determine the power transmitted; also known as Torsionmeter.

Torsion - Torsion - a twisting action in which load applied to a member causes the member to twist (or

rotate) about its longitudinal axis. Torsion - a twisting deformation of a solid body about an axis in which lines that were initially

parallel to the axis become helices. Torsion - the application of twist without any bending. Torsion - the stress produced in a body, such as a shaft or stem, by twisting one end while the

other end is held firm or twisted in the other direction. Torsion - the twisting of material by force which turns one end of a bar about its longitudinal axis

while the other end is either clamped in a rigid fixture or twisted in the opposite direction. Torsion develops shear stresses in the material and occurs in such applications as propeller shafts, springs etc.

Torsional Strength - the ability of rubber to withstand twisting. Total Depth - the total thickness of weld overlay or back cladding. Toughness - Toughness - 1) the property of a material which enables it to withstand bending or torsion without

fracture. It is highly desirable property of any metal; 2) the resistance of a material to fracture by bending, twisting, fatigue or impact of load. Toughness enables materials to undergo relatively large deformations at high stress. Defection of a test piece under load gives some indication of the toughness of a material. This factor depends upon the chemical composition and the heat treatment given.

Toughness - a condition which is intermediate between brittleness and softness, and indicated by a high ultimate tensile stress. With a low to moderate elongation and area reduction of a test-piece, plus a high value in a notched-bar test.

Toughness - a property of a material capable of absorbing energy by plastic deformation; intermediate between softness and brittleness.

Toughness - resistance of a material to repeated bending and twisting, as measured by the work needed to break it during an impact test.

Toughness - the ability of materials to resist shatter. If a material shatters it is brittle (e.g. glass). If it fails to shatter when subjected to an impact load it is tough (e.g. rubber). Toughness should not be confused with strength. Any material in which the spread of surface cracks does not occur or only occurs to a limited extent is said to be tough. Impact resistance.

Toughness - the ability to withstand high unit stress along with great unit deformation without complete fracture.

Toughness - the amount of energy that a material absorbs before fracture. It is also known as the ability of a material to resist impact. Toughness is a measure of ultimate energy strength and is associated with high values of notched bar tests. The value of toughness is very useful in the selection of a material where impact loads are frequently applied.

Toughness - the amount of energy that a material absorbs before fracture. It is also known as the ability of material to resist impact. Toughness is a measure of ultimate energy strength and is associated with high values of notched bar tests. The value of toughness is very useful in the selection of a material where impact loads are frequently applied.

Toughness - the property of a metal which enables it to be twisted, bent or stretched without rupture. Mild steel and copper etc. are examples of tough metals.

Toughness Index - refers to the ratio between the index of plasticity and the flow index. TPI - Third Party Inspector TRA - Thermal Relief to Atmosphere Traceable Mill Certificate - a document that permits each component to be identified according

to the original heat or material from which it was produced. Transducer - Transducer - 1) an element or device which receives information in the form of one quantity and

converts it to information in the form of the same or another quantity; 2) a device which provides a usable output in response to a specified measurand. NOTE: the term transducer is usually preferred to Sensor and Detector and to such terms as Flowmeter, Accelerometer and Tachometer; it is always preferred to Pickup, Gage (when not equipped with a dial indicator), Transmitter (which has an entirely different meaning in telemetry technology), Cell, and End Instrument; 3) a device to convert one form of signal to another; 4) a general term for a device that receives information in the form of one or more physical quantities, modifies the information and/or its form, if required, and produces a resultant output signal. Depending on the application, the transducer can be a primary element transmitter, relay, converter or other device. Because the term transducer is not specific, its use for specific applications is not recommended.

Transducer - an element or device which receives information in the form of one quantity and coverts it to information in the form of the same or another quantity; see I/P.

Transducer - an element used to convert one form of energy into another, e.g., pressure into electrical voltage.

Transferred Arc Process - a plasma arc welding process in which an arc is struck between the electrode and the workpiece. The transferred arc possesses high energy plasma jet velocity. Due to high velocity it is mainly used for cutting and melting metals. For initiating the plasma arc, a current limiting resistor is used. It permits the flow of high current between the nozzle and the electrode.

Transformation Ranges - those ranges of temperature for steels within which austenite forms during heating and transforms during cooling. The two ranges are distinct, sometimes overlapping, but never coinciding.

Transformation Temperature - the temperature at which phase changes occur during the

heating of iron and steels. Transformer - a device for reducing or increasing the voltage of an alternating current by

electromagnetic induction. Transition Metals - most industrial metals, chromium, manganese, iron, copper, nickel and zinc

are known as the transition metals and form one continuous block in the periodic table from Group IIIB to IIB. They have high melting points and high densities, which increase their atomic number. Aluminum stands outside this block and is in Group III of the periodic table with a much lower density and melting point.

Translate - to move from one place or condition to another. Translating Stem Valve - a gate, globe, or diaphragm valve. The valve stem moves along its

primary axis, and may also simultaneously rotate. Translation - the linear movement of a point in space without any rotation. Translational Motion - motion of a rigid body in such a way that any line which is imagined

rigidly attached to the body remains parallel to its original direction. Transversal - a line that cuts across a set of other lines. Transverse - extending across something in a crosswise direction. Trapezoid - a four-sided figure with only one pair of sides parallel, and no right angles. Trapped Air - air which is trapped in a product or a mold during cure. Usually causes a loose ply

or cover, or a surface mark, depression or void. Travel - Travel - the amount of movement of the closure member from the closed position to an

intermediate or the rated full open position. Travel - the distance of a mechanical stroke Travel - the distance the plug or stem moves in order to go from a full-closed to a full-open

position; also called Stroke. Travel Coefficient - The ratio between the flow at a given valve stem position and the flow

through the valve at its wide open position, usually expressed as a decimal fraction. Example: If a valve having a lift of one inch passes 100 gal/min when fully open and passes 66 gal/min at a valve lift of.5-inch, this valve is said to have a.66 valve travel coefficient at a.5-inch lift. Valve travel coefficients can be read directly from any plot showing valve flow characteristics.

Travel Indicator - a means of externally showing position of the closure member; typically in terms of percent of or degrees of opening. It can be a visual indicator at or on the valve or a remote indicating device by means of transmitter or appropriate linkage.

Travel Indicator Scale - a scale or plate fastened to a valve and marked with graduations to indicate the valve opening position.

Traverse - movement to right or left on a pivot or mount. TRB - Thermal Relief to Body Treat - to put something through a process or apply something to it. Treated Iron - molten cast iron to which all basic alloys and nodulizing alloys have been added

but not necessarily all inoculating alloy additions. TRG - Thermal Relief valve with Gauge Trim - Trim - a collective term relating to the materials of certain major internal valve components which

are directly affected by the fluid or by the action of the fluid flow through the valve. When the trim components are made in materials of similar composition but not necessarily similar mechanical properties, the valve is referred to as having a ‘trim’ of that specific material, for example, ‘13% chrome trim’. When the components are of dissimilar materials, the material of each is specified separately.

Trim - a collective term relating to the materials of certain major internal components which are directly affected by the fluid or by the action of the flow thereof through the valve. Where these components are made in materials of similar composition but not necessarily with similar mechanical properties, the valve is referred to as having a “trim” of that specific material, e.g. “13 per cent chrome trim”. Where the components are of dissimilar materials, the material of each is specified separately.

Trim - commonly refers to the valve’s working parts and to their materials. Usually includes seat ring sealing surfaces, closure element sealing surfaces, stems, and back seats.

Trim numbers which specify the materials are defined in API 600 and API 602. Trim - includes all the parts that are in flowing contact with the process fluid except the body,

bonnet, and body flanges and gaskets. The plug, seats, stem, guides, bushings, and cage are some of the parts included in the term trim.

Trim - the internal components of a valve which are exposed to the flowing fluid. Trim - the internal parts of a valve which are in flowing contact with the controlled fluid. Trim - the materials of the disc, body seat ring and stem of valves and stating the percentage of

some element of the alloy of which the part is made, such as ’13% chrome trim’. Trim - the process involving removal of mold flash. Trim - the valve parts inside the shell that come in contact with the fluid (“wetted”), generally the

flow control element, its mover (stem or shaft), and the seat rings. Trim - tim consists of all parts of a valve that are in contact with the flowing medium but are not

part of the valve shell or casting. Thus, plugs, seats, discs, stems, packing rings, etc. are all trim components. The term "trim" is usually used in connection with trim materials.

Trim Cut - damage to mold skin or finish by too close trimming. Trim, Anti Cavitation - Trim, Anti Cavitation - a combination of control valve trim that by its geometry reduces the

tendency of the controlled liquid to cavitate. Trim, Anti Cavitation - a combination of plug and seat ring or plug and cage that by its geometry

permits noncavitating operation or reduces the tendency to cavitate, thereby minimizing damage to the valve parts, and the downstream piping.

Trim, Anti Cavitation - a special trim used in control valves to stage the pressure drop through the valve, which will either prevent the cavitation from occurring or direct the bubbles that are formed to the center of the flow stream away from the valve body and trim. This is usually accomplished by causing the fluid to travel along a torturous path or through successively smaller orifices or a combination of both.

Trim, Anti Noise - Trim, Anti Noise - a combination of control valve trim that by its geometry reduces the noise

generated by fluid flowing through the valve. Trim, Anti Noise - a combination of plug and seat ring or plug and cage that by its geometry

reduces the noise generated by fluid flowing through the valve. Trim, Balanced - Trim, Balanced - a trim arrangement that tends to equalize the pressure above and below the

valve plug to minimize the net static and dynamic fluid flow forces acting along the axis of the stem of a globe valve. Some regulators also use this design, particularly in high pressure service.

Trim, Balanced - an arrangement of ports and plug or combination of plug, cage, seals and ports that tends to equalize the pressure above and below the valve plug to minimize the net static and dynamic fluid flow forces acting along the axis of the stem of a globe valve.

Trim, Balanced - control valve trim designed to minimize the net static and dynamic fluid flow forces acting on the trim.

Trim, Characterized - control valve trim that provides a predefined flow characteristic. Trim, Choke - choke components, including beans, one piece stems, multi piece stems etc. Trim, Erosion Resistant - valve trim that has been designed with special surface materials or

geometry to resist the erosive effects of the controlled fluid flow. Trim, Globe Valve - the internal parts of a valve which are in flowing contact with the controlled

fluid. Examples are the plug, seat ring, cage, stem and the parts used to attach the stem to the plug. The body, bonnet, bottom flange, guide means and gaskets are not considered as part of the trim.

Trim, Reduced - Trim, Reduced - an undersized orifice. Reduced or restricted capacity trim is used for several

reasons: a) it adapts a valve large enough to handle increased future flow requirement with trim capacity properly sized for present needs; b) a valve with adequate structural strength can be selected and still retain reasonable travel vs. capacity relationships; c) a valve with a large body using restricted trim can be

used to reduce inlet and outlet fluid velocities; d) it can eliminate the need for pipe reducers; e) errors in over sizing can be corrected by use of restricted capacity trim.

Trim, Reduced - control valve trim which has a flow area smaller than the full flow area for that valve.

Trim, Restricted - control valve trim which has a flow area less than the full flow area for that valve.

Trim, Soft-Seated - a valve trim with an elastomeric, plastic or other readily deformable material used either in the closure component or seat ring to provide shutoff with minimal actuator forces.

Trip - to release a lever or set free a mechanism. TRM - Technology Resource Management Troostite - Troostite - a phase of steel if martensite is reheated (tempered). In the case of plain steels

between temperatures 205° to 395° C., troostite is formed. Troostite is softer and more ductile than sponeroidite. Troostite consists of sub-microscopic particles of cementite.

Troostite - fine pearlite found in steels. It is obtained by the slow cooling from the hardening temperature. It is also produced by tempering martensite between 200° and 450°C. It differs from pearlitic structure in its degree of fineness only. Under a high power microscope, it is seen in the form of alternate layers of ferrite and cementite.

TRP - Technical Requisition Package TRS - Technology Resource Management (Petronas) Truncate - to cut off the top or end Trunnion - Trunnion - 1) a short shaft extension at the bottom of a trunnion ball; 2) a pin or pivot forming

one of a pair on which something is supported. Trunnion - 1) either of two opposite pivots, journals, or gudgeons, usually cylindrical and

horizontal, projecting one from each side of a piece of ordnance, the cylinder of an oscillating engine, a molding flask, or a converter, and supported by bearings to provide a means of swiveling or turning; 2) a pin or pivot usually mounted on bearings for rotating or tilting something.

Trunnion - extensions of the ball used to locate, support and turn the ball within the valve body. May be integral or attached to the ball.

Trunnion - the part of a ball valve which holds the ball on a fixed vertical axis and about which the ball turns.

Trunnion Ball - a flow control element of a ball valve that is held in position in the body by two integral, short-shaft extensions (trunnions) on the ball.

Trunnion Bearing - Trunnion Bearing - a bearing inserted in the trunnion boss to support the trunnion. Trunnion Bearing - a bearing on which a vessel or cylinder can rotate or oscillate. Trunnion Boss - a boss formed on or in the body to support the trunnion. Trunnion Mounting - Trunnion Mounting - a pair of short journals, supported in bearings, projecting co-axially from

opposite sides of a vessel or cylinder required to pivot about their axis. Trunnion Mounting - a style of mounting the disc or ball on the valve shaft or stub shaft with two

bushings diametrically opposed. Trunnion Thrust Bearing - the thrust bearing used to support thrust loads on the ball trunnion. TSE - Threaded Small End TSO - 1) Tight Shut Off (valve); 2) Total Shut Off TSSC - Technical Standards Steering Committee TT - Threaded equal Tee Tuberculation - a condition which develops on the interior of pipelines due to corrosive materials

present in the fluid passing through the pipe, and which results in the creation of small, more or less hemispherical lumps (tubercules) on the walls of the pipe, which increase the friction loss, and by reducing the velocity also reduce the capacity of the pipe.

Tubing - Tubing - a type of fluid line whose dimensions are designated by actual measured outside

diameter and by actual measured wall thickness. Tubing - when referring to OCTG, tubing is a separate pipe used within the casing to conduct the

oil or gas to the surface. Depending on conditions and well life, tubing may have to be replaced during the operational life of a well.

Tubular Component - a cylindrical component (pipe) having a longitudinal hole that is used in drilling / production operations for conveying fluids.

Tundish - the shallow refractory-lined basin on top of the continuous caster. It receives the liquid steel from the ladle, prior to the cast, allowing the operator to precisely regulate the flow of metal into the mold.

Tungsten (W) - Tungsten (W) - a very hard, dense, silvery-white metallic element with a very high melting point. Tungsten (W) - this metal has the highest melting point of any metal; it is used as an alloying

element in steel to increase strength and hardness at very high temperatures such as for high-speed tools.

Tungsten (W) - tungsten is soluble both in a-iron and i-iron. It forms different carbides like Wc, W2C, Fe3W3C and Fe4W2C with carbon. A compound with iron Fe3W2 provides an age-hardening system. Tungsten raises the critical points in steel and the carbides dissolve slowly over a range of temperatures. When completely dissolved, the tungsten renders transformation sluggish, especially to tempering, and its use is made of in most hot working tools like high-speed steel and die steels. Tungsten provides the property of red hardness to steel. It is used in magnets, corrosion and heat-resisting steels. It refines the grain size and produces less tendency to decarburization during working.

Tungsten Carbide - Tungsten Carbide - a very hard material which is used to strengthen the cutting edge of a boring

tool. Tungsten Carbide - an extremely hard coating used in tools, abrasives and wear resistant parts. Tungsten Inert Gas Arc Welding (TIG) - a non-consumable electrode inert gas arc welding

process. In this process coalescence is produced by the heat of an electric arc produced between a tungsten electrode and the workpiece. The electrode does not melt and becomes a part of the weld. Filler metal is required and is fed into the weld zone and melted with the base metal in the same manner as that used with oxy-acetylene welding. The molten metal pool is protected by shielding it with an inert gas. The inert gases generally used are helium or argon. In this process AC currents are used for welding light materials. DC may be use for welding heavier metals.

Tungsten Inert Gas Arc Welding (TIG) - Tungsten Inert Gas Arc Welding (TIG) - a non-consumable electrode inert gas arc welding

process. In this process, coalescence is produced by the heat of an electric arc produced between the tungsten electrode and the work piece. The electrode does not melt and become a part of the weld. A filler metal, if required, is fed into the weld zone and melted with the base metal in the same manner as used in oxy-acetylene welding. This process is used for welding copper, nickel, aluminum, magnesium, zinc and their alloys. It is also suitable for welding stainless steels, and high temperature welding materials like inconel, titanium and zirconium.

Tungsten Inert Gas Welding - a nonpreferred term for gas tungsten arc welding; also known as TIG welding.

Turbine - a rotary motor actuated by the reaction, impulse, or both, of a flow of pressurized fluid. Turbulence - Turbulence - a state of unsteady flow in which a liquid has been subjected to disturbance. Turbulence - any deviation from parallel flow in a pipe due to rough inner walls, obstructions or

directional changes. Turnaround - the process of completing or the time needed to complete a task. Turndown - Turndown - a term used to describe the ratio between the minimum and maximum flow

conditions seen in a particular system. Example: If the minimum flow is 10 Gallons

Per Minute and the maximum flow is 100 Gallons Per Minute, the turndown would be 10:1. This term is sometimes incorrectly applied to valves; see alsoRangeability.

Turndown - the ratio between maximum usable flow and the minimum controllable flow, usually less than the rangeability. For instance, as stated above, after the 100 gal/min valve has been applied at a job, it might turn out that the most flow you would ever need through the valve is 68 gal/min. Since the minimum controllable flow is 2 gal/min, the turndown for this valve is 34 to 1. In comparing rangeability and turndown, we may say that rangeability is a measure of the predicted stability of the control valve, and turndown is a measure of the actual stability of the valve.

Turning - a method of cold-finishing by machining to size in a lathe or turning machine to remove surface metal formed during hot-rolling.

Turnkey Contract - a contract in which an independent agent undertakes to furnish for a fixed price all materials and labor, and to do all the work needed to complete a project.

Turns to Operate - the number of complete revolutions of a handwheel or the pinion shaft of a gear operator required to stroke a valve from fully open to fully closed or vice versa.

TWA - Time Weighted Average Twin Carbon Arc Welding - an arc welding process in which heat is produced by producing an

arc maintained between two carbon electrodes and by using a non-ferrous filler metal.

Two Phase - a fluid state comprising a mixture of liquid with gas or vapors. Two Piece Ball Valve - a ball valve in which the valve is made up from the body and a body

connector, each of which has a body end. Two Piece Element Clamp - a two piece element clamp or pinch valve is a valve consisting of

two flexible elastomeric elements or liners installed between a two piece flanged body. The flexible elements or liners also extend over the flange faces and act as gaskets between the valve and the connecting piping; compare with One Piece Element Clamp; see Pinch Valve.

Two Piece Gland - a bolted design in which the gland of a valve is separate from the gland flange, generally having a self-aligning feature.

Two Way Valve - a mechanical device that controls the flow of fluid by allowing flow in either of two directions.

TWSG - Thermowell Straight TXS - male Thread one end X Socket welded one end Type of Protection ‘d’ - an enclosure for electrical apparatus that will withstand an internal

explosion of the flammable gas or vapor which may enter it without suffering damage and without communicating the internal inflammation to the external flammable gas or vapor for which it was designed, through any joints of structural openings in the enclosure.

Type of Protection ‘e’ - the method of protection by which additional measures are applied, so as to give increased security against the possibility of excessive temperatures and of the occurrence of arcs and sparks in apparatus which does not produce arcs or sparks in normal service.

Type of Protection ‘n’ - a type of protection applied to electrical apparatus such that, in normal operation, it is not capable of igniting a surrounding explosive gas atmosphere and a fault capable of causing ignition is not likely to occur.

Type of Protection ‘p’ - an enclosure in which a protective gas is maintained at a pressure greater than that of the surrounding atmosphere, so as to prevent the introduction of explosive mixtures from the surrounding atmosphere.

U Bolt - a U-shaped bolt with threads at the ends of both arms to receive nuts. U Cup - a type of seal. A U-cup is an O-ring formed into a U-shaped channel. Liquid or air

pressure "inflates" the U-cup and affects a seal. The U-cup is used in instances

where an O-ring is not desirable. UB - Union Bonnet UKOOA - United Kingdom Offshore Operators Association UL - Underwriters Laboratory Ultimate Elongation - see Elongation Ultimate Load - see Breaking Load Ultimate Strain - the unit elongation (elongation per unit of length) at the specimen breaking-

point. It is a measure of ductility. Ultimate Strength - Ultimate Strength - it is the highest unit stress it can sustain before rupturing. Ultimate Strength - see Tensile Strength Ultimate Strength - the breaking load of a material under tension; also called Tensile Strength. Ultimate Strength - the maximum load that a specimen of a material can sustain divided by the

original cross sectional area of the specimen. Ultimate Strength - the maximum stress needed to break a specimen. Ultimate Strength - the maximum stress which a material is able to withstand without any failure. Ultimate Strength - the stress level at which the pipe will fail/rupture or "break." The ultimate

strength of the steel is determined by testing during the manufacture of the pipe. Ultimate Strength - the tensile stress, per unit of the original surface area, at which a body will

fracture, or continue to deform under a decreasing load. Ultrasonic Inspection (UT) - Ultrasonic Inspection (UT) - an inspection procedure using high frequency sound waves to

detect wall thickness or flaws throughout the thickness of metal parts; sometimes called Ultrasonic Test.

Ultrasonic Inspection (UT) - due to piezo electric effect, certain crystals can be made to vibrate when influenced by an oscillating electric current. For ultrasonic inspection, the crystal is made to vibrate at frequencies ranging from half to 10 Mc/sec, and when held against a piece of steel causes the vibrations to travel through the steel and to be reflected back from the opposite side or from any intervening defects. The echoes are made visible on a cathode-ray tube.

Ultrasonic Leak Detector - an instrument which detects ultrasonic energy resulting from the transition from laminar to turbulent flow of a gas passing through an orifice.

Ultrasonic Testing - Ultrasonic Testing - a nondestructive testing method in which high frequency sound waves are

projected into a solid to detect and locate flaws, to measure thickness, or to detect structural differences.

Ultrasonic Testing - the use of very high frequency sound waves to investigate the continuity of the material of a work piece.

Ultrasonic Testing - ultrasonic vibrations are used to locate defects in ferrous metals, non-ferrous metals as well as plastics and ceramics. Ultrasonic waves are usually generated by the piezo-electric effect which converts the electrical energy to mechanical energy. A quartz crystal is used for this purpose. Pulses of high frequency (20 KHz to 20 MHz) are applied to the part under test. In the interval between pulses, a crystal detects echoes reflected either from the far edge of the test bar or from any flaws in the path of the beam. The signals received are shown on a cathode ray tube, which also has a time base connected to it. The position of the signal on the screen gives an indication of the distance between the crystal generator and the surface from which the echo originates. Ultrasonic testing is employed to detect and locate defects such as shrinkage cavities, internal bursts or cracks, porosity and non-metallic inclusions. It is useful for routine inspection of locomotive axles also. This method of inspection is non-destructive, fast and reliable. The minimum flaw size which can be detected is equal to about 0.1% of the distance from the probe to the defect.

Ultrasonic Welding - a type of solid state welding process in which coalescence is produced by the local application of high frequency (ultrasonic) vibratory energy to the workpieces. The frequency of vibrations varies from 15 KHz to 170 KHz. The workpieces are clamped together and high frequency (ultrasonic) shear stresses are applied parallel to the plane. Ultrasonic vibrations and pressure causes

movement of the metal molecules to bring a strong union of workpieces. Ultrasonic welding is a rapid process and the time of weld varies from 0.5 to 2.0 second, depending upon the size and characteristics of the material. Ultrasonic welding equipment consists of a transducer-coupling system, frequency converter, anvil, force application device, a timer and appropriate hydraulic, pneumatic, electrical and electronic control. Pieces to be welded are held between the tips of the electrode and the anvil. A motor generator set (frequency converter) converts normal frequency to high frequency. The transducer converts the high frequency electrical power into ultrasonic vibratory energy. This energy is transmitted to the joint through the welding tip attached to the transducer. The tip oscillates in the plane of the joint interface and induces dynamic shear stresses in the workpieces. It results in local plastic deformation of joint materials to form a coalesced weld joint on cooling. Depending upon the type of joints ultrasonic welding can be classified into spot welding, line welding, ring welding, and continuous stream welding. Ultrasonic welding is used for welding a large number of similar and dissimilar materials like copper, aluminum, beryllium, geranium, gold, iron, all types of steels, nickel, niobium, platinum, silver and their alloys. Even glass and plastics can be welded by this process.

Ultrasound - sound consisting of waves with frequencies higher than 20,000 Hertz (above the limit of human hearing). It is used for detecting flaws and impurities in metal.

UMC - Underwater Manifold Center Unalloyed Steel - carbon-manganese steels, including 0.3% and 0.5% molybdenum steels. UNCITRAL - United Nations Commission on International Trade Law Under Cure - a degree of cure less than optimum. May be evidenced by tackiness, loginess, or

inferior physical properties. Underbead Crack - a crack in the heat affected zone of a weldment that does not extend to the

base metal surface. Undercutting - a welding defect in which a groove created into the base metal adjacent to the

toe of the weld is left unfilled. This defect is related to reduction in plate section or burning away of the sidewalls of the joint. The main cause of this defect is excessive welding current resulting in the melting of relatively large section of the workpiece at the corner of the welds. Excessive speed of travel of the electrode leaves the groove unfilled or partially filled. One-sided undercut is produced due to concentration of heat on one side. Bad positioning of the component plates also contribute to undercutting.

Underwater Safety Valve - valve used in an underwater wellhead location which closes upon loss of power, uses a USV actuator.

Underwriters Laboratories (UL) - an independent USA testing and certifying organization. Unfired Pressure Vessel - Unfired Pressure Vessel - a pressure vessel that is not in direct contact with a heating flame. Unfired Pressure Vessel - a vessel designed to withstand internal pressure, neither subjected to

heat from products of combustion nor an integral part of a fired pressure vessel system.

Unidirectional Valve - a valve designed for sealing in one direction only. Unified Screw Thread - Unified Screw Thread - a system of standard 60 degree V threads that are classified coarse, fine

and extra fine (UNC, UNF and UNEF) to provide different levels of strength and clamping power.

Unified Screw Thread - three series of threads: coarse (UNC), fine (UNF), and extra fine (UNEF); a one quarter inch-diameter (0.006 millimeter) thread in the UNC series has 20 threads per inch, while in the UNF series it has 28.

Union - a screwed or flanged pipe coupling usually in the form of a ring fitting around the outside of the joint.

Union Bonnet - a type of valve construction in which the bonnet is held on by a union nut with threads on the body.

Union Joint - Union Joint - a body-bonnet joint in which a female-threaded nut slides over the bonnet and

screws onto a male-threaded body, clamping the bonnet in place.

Union Joint - a threaded assembly used for the joining ends of lengths of installed pipe or tubing where rotation of neither length is feasible.

Unit Cost - a pricing system based upon the cost of individual items, as opposed to a Lump Sum (for an aggregate of items).

Unit Strain - 1) for tensile strain, the elongation per unit length; 2) for compressive strain, the shortening per unit length; 3) for shear strain, the change in angle between two lines originally perpendicular to each other.

United States Standard Dry Seal Thread - a modified pipe thread used for pressure-tight connections that are to be assembled without lubricant or sealer in refrigeration pipes, automotive and aircraft fuel-line fittings, and gas and chemical shells.

Universal Coupling - a joint or coupling that can transmit rotary power by a shaft at any angle. Unloading Valve - a pressure control valve whose primary function is to permit a pump or

compressor to operate at minimum load. UNS - Unified Numbering System Unshielded Metal Arc Welding - a welding process using a metallic electrode where no

shielding medium is used. Unsoundness - the condition of a solid metal which contains blowholes or pinholes due to

gases, or cavities resulting from its shrinkage during contraction from liquid to solid state, i.e. contraction cavities.

UOM - Unit Of Merchandise Upper Spreader - the component of a double disc gate valve which is attached to, or engages,

the actuating thread of the stem, and which, in conjunction with the lower spreader and the stop in the body, constitutes the spreading mechanism which forces the discs apart against the body seats when the valve is closed.

Upper Spreader Bushing - a bushing in a double disc gate valve, secured in the upper spreader and threaded internally to engage the actuating thread of the stem. It is associated only with non-rising stem.

Upper Spreader Nut - in a double disc gate valve, the nut retained in the upper spreader and threaded internally to engage the actuating thread of the stem. It is associated only with non-rising stem.

Upset - Upset - metalworking in order to produce an increase in section of part of a component over and

above its starting size, as in the forming of the head of a bolt or rivet from a round bar.

Upset - to cause a local increase in diameter or other cross sectional dimension by applying an axial deforming force to a piece of rod or wire, such as is used to produce heads on nails or screws.

Upset Butt Welding - see Butt Welding Upset Forging - in upset forging operation, a bar of uniform section is gripped in the fixed half of

the die so that the requisite length projects, and pressure is applied at the heated end thus causing it to upset or be formed into some desired shape.

Upstream - Upstream - the inlet side of an instrument. Upstream - the process of developing oil fields, exploring for oil, and producing oil from oil fields.

Downstream is the opposite of upstream. Upstream Operations - oil and natural gas exploration and production, and gas processing

activities. UPVC - Unplasticized PVC UT - 1) Ultrasonic Examination; 2) Ultrasonic Test UTS - Ultimate Tensile Strength

V - 1) Vanadium; 2) Vital; 3) Vent / flare, non corrosive, onshore or offshore; 4) flare and vent, sweet

VAC - Volts Alternating Current Vacuum - Vacuum - a region in which the air pressure is less than atmospheric pressure. Vacuum - refers to the pressures below atmospheric. Vacuum - the term denoting a given space that is occupied by a gas at less than atmospheric

pressure. For degrees of vacuum; see Vacuum Level. Vacuum Breaker - a device used in a water supply line to relieve a vacuum and prevent

backflow; also known as 'Backflow Preventer. Vacuum Degassing - an advanced steel refining facility that removes oxygen, hydrogen and

nitrogen under low pressures (in a vacuum) to produce ultra-low-carbon steel for demanding electrical and automotive applications. Normally performed in the ladle, the removal of dissolved gases results in cleaner, higher-quality, more pure steel; see Ladle Metallurgy.

Vacuum Fusion - a laboratory technique for determining dissolved gas content of metals by melting them in vacuum and measuring the amount of hydrogen, oxygen and sometimes nitrogen released during melting; the process can be used on most metals except reactive elements such as alkali and alkaline earth metals.

Vacuum Level - the term used to denote the degree of vacuum evidenced by its pressure in torr (or mm Hg). a) Rough vacuum - 760 torr to 1 torr; b) Medium vacuum - 1 torr to 10-3 torr; c) High vacuum - 10-3 torr to 10-6 torr; d) Very high (hard) vacuum - 10-6 torr to 10-9 torr; e) ultra high (ultra hard) vacuum-below 10-9 torr.

Vacuum Oxygen Decarburization (VOD) - process for further refinement of stainless steel through reduction of carbon content. The amount of carbon in stainless steel must be lower than that in carbon steel or lower alloy steel (i.e., steel with alloying element content below 5%). While electric arc furnaces (EAF) are the conventional means of melting and refining stainless steel, VOD is an economical supplement, as operating time is reduced and temperatures are lower than in EAF steelmaking. Additionally, using VOD for refining stainless steel increases the availability of the EAF for melting purposes. Molten, unrefined steel is transferred from the EAF into a separate vessel, where it is heated and stirred by an electrical current while oxygen enters from the top of the vessel. Substantial quantities of undesirable gases escape from the steel and are drawn off by a vacuum pump. Alloys and other additives are then mixed in to refine the molten steel further.

Vacuum Relief Valve - Vacuum Relief Valve - a pressure relief device which is designed to allow fluid to enter a

pressure vessel in order to avoid extreme internal vacuum. Vacuum Relief Valve - a valve automatic in operation used to release vacuum when filling or

emptying a pipeline or tank; sometimes called a Vacuum Breaker Valve. Valve - Valve - 1) a valve is a device used for the control of fluid flow. It consists of a fluid retaining

assembly, one or more ports between end openings and a movable closure member which opens, restricts or closes the port(s); 2) an in line device in a fluid flow system that can interrupt flow, regulate the rate of flow, or divert flow to another branch of the system.

Valve - a device for regulating the flow of fluid through a system. Valve - a device that controls fluid flow direction, pressure, or flow rate. Valve - a device to regulate or stop the flow in a pipe. Valve - a device used to control the flow of fluid contained in a pipe line. Valve - a device used to regulate the flow of fluids in piping systems and machinery. Valve - a device which dispenses, dissipates, or distributes energy in a system. Valve - a mechanical device used to control the flow of fluid in piping systems. Valve - in plumbing, a device to control the flow of liquid through a pipe. Valve Body - Valve Body - see Body Valve Body - the main part of a valve. It contains the passages for the flow medium, seating

surfaces and inlet and outlet fittings. Valve Body Assembly - an assembly of a body, bonnet assembly, bottom flange and trim

elements. The rim includes a valve plug which opens, shuts or partially obstructs one or more ports.

Valve Face - the sealing surface of a valve which slides over, or beds on to the seating. Valve Flow Coefficient (CV) - see Cv Valve Flow Coefficient (CV) - Valve Flow Coefficient (CV) - the number of US gallons per minute of 60°F water that will flow

through a valve with a one pound per square inch pressure drop. Valve Follower - a linkage that transmits motion from a cam to the push rod of a valve,

especially in an internal combustion engine. Valve Gain - see Flow Characteristic Valve Guide - a channel which supports the stem of a valve for maintenance of alignment. Valve Head - Valve Head - the closing components of the valve on which the valve head face is formed. Valve Head - the disk part of a poppet valve that gives a tight closure on the valve seat. Valve Head Face - a machined face which makes contact with the body seat when the valve is

closed. Valve Head Guide Wings - Valve Head Guide Wings - that part connected to the cover by pillars and in which the adjusting

screw engages. Valve Head Guide Wings - that part of the valve head which, when in the form of wings, guides

the valve head to the body seat. Valve Head Pin - 1) the component which makes contact with the body seat when the valve is

closed; 2) the component which connects the valve head to the spindle. Valve Lifter - a device for opening the valve of a cylinder as in an internal combustion engine. Valve Plug - Valve Plug - an obsolete term; see Closure Member, which is the preferred term. Valve Plug - see Closure Member Valve Plug - the part of a valve which moves to restrict the area through which the fluid travels. Valve Seat - the circular metal ring on which the valve head of a poppet valve rests when closed.Vanadium - Vanadium - used to refine the grain size and enhance the mechanical properties of steel. Vanadium - vanadium forms a carbide V4C3 and has beneficial effects on the mechanical

properties of heat-treated steel, especially in the presence of other elements. It is a strong deoxidizer. It toughens and strengthens steel. It refines the grain and reduces the grain growth. It widens the hardening range and hardness is retained at higher temperatures than carbon steel. With other elements, it slows up tempering in the range of 500° to 600° C and can induce induction hardening. With chromium it forms double carbides and gives a “keen edge” quality to steel. Chromium-Vanadiums (0 to 17%) are used for coil springs, torsion bars, automobile axles and locomotive forgings.

Vapor - Vapor - 1) the gaseous form of any substance which is usually a liquid or a solid; 2) a gas that

can be condensed to a liquid by pressure alone, without being cooled; 3) a gas whose temperature and pressure are very near the liquid phase. Dry steam is considered a vapor because its state is normally near that of water. (Wet steam is a two-phase mixture of vapor and fluid particles.)

Vapor - the gaseous state of a fluid that normally exists as a liquid under atmospheric conditions, i.e. a gas whose temperature is below its critical temperature.

Vapor Space Length - the distance between the bottom of the stuffing box and the top of the: (a) bonnet bushing for rising stem (gate and globe) valves, or (b) body stem bearing for rotary (e.g. ball and high performance butterfly) valves. (Note: the bottom of the stuffing box means excluding the room for a spacer that may be installed below the packing rings.)

VB - Valve, Ball VC - 1) Valve, Check; 2) Vent / flare, Corrosive, onshore or offshore

VCI 386 - a clear water based rust inhibiting primer VDBT - Valve Ass. Double Block Ball Threaded VDC - Volts Direct Current VDCC - Vendor Document Control Center VDP - Vendor Development Program VDRL - 1) Vendor Data Requirement List; 2) Vendor Documentation Requirement List VDRS - Vendor Document Requirement Schedule Vector - 1) a quantity having magnitude and direction, as contrasted with a scalar which has

quantity only; 2) a one-dimensional matrix. Vee Orifice - a "V"-shaped flow control orifice which allows a characterized flow control as the

gate moves in relation to the fixed Vee opening. Velocities in Pipes - experience has proved that the following have been allowable velocities in

pipes: for air 30 to 50 ft/sec, compressed air 25 to 40 ft/sec, steam 160 to 250 ft/sec, and water 5 to 10 ft/sec.

Velocity - Velocity - the rate of change of position with time. Common units are meters per second (SI

metric) and feet per second (British). Velocity - the rate of motion in a particular direction. The velocity of fluids is usually expressed in

feet per second. Velocity - time rate of motion in a given direction and sense, usually expressed in feet per

second. Vena Contracta - Vena Contracta - the location where cross sectional area of the flowstream is at its minimum.

The vena contracta normally occurs just downstream of the actual physical restriction in a control valve.

Vena Contracta - the location where cross-sectional area of the flow stream is at its minimum size, where fluid velocity is at its highest level, and where fluid pressure is at its lowest level. The vena contracta normally occurs just downstream of the actual physical restriction in a control valve.

Vendor Document Requirement Schedule - document lists submitted by vendor, listing all contract data with its appropriate document numbering and guidance on its completion and submission; abbreviated VDRS.

Vendor Documentation Requirement List (VDRL) - a list of documents issued with the enquiry, specifying the minimum information required from vendor.

Vent - Vent - an opening for the release of air or gas into an open area to prevent pressure buildup. Vent - an opening provided for the discharge of pressure or the release of pressure from tanks,

vessels, reactors, processing equipment, and so on. Vent Port - an opening that allows air, gas or liquid into or out of a confined space. Venting of Valve Plate / Poppet - provision for venting of any gas which might be trapped in the

seal groove by means of a pump out opening. Venturi - Venturi - a constriction in a pipe, tube or flume consisting of a tapered inlet, a short straight

constricted throat and a gradually tapered outlet; fluid velocity is greater and pressure is lower in the throat area than in the main conduit upstream or downstream of the venturi; it can be used to measure flow rate, or to draw another fluid from a branch into the main fluid stream.

Venturi - a tube having a narrowing throat or constriction to increase the velocity of fluid flowing through it. The flow through the venturi causes a pressure drop in the smallest section, the amount being a function of the velocity of flow.

Venturi Meter - Venturi Meter - a flow meter which is used for closed pipes, in which a constriction is followed by

an expansion to normal width. Venturi Meter - a meter in which flow rate is measured in terms of pressure drop across a venturi

in a pipe. Venturi Meter - an instrument for efficiently measuring fluid flow rate in a piping system; a nozzle

section increases velocity and is followed by an expanding section for recovery of

kinetic energy. Venturi Pattern - having reduced-area seat port, and a body throat approaching a venturi. Venturi Port - a valve bore (port) found on plug valves that is substantially smaller than a full

port, approximately 40% to 50% of full bore; compare with Full Port, Regular Port, and Reduced Port.

Venturi Tube - a closed pipe which is gradually contracted to a throat, causing a reduction of pressure head by which velocity through the throat may be determined. The contraction is generally followed, but not necessarily so, by gradual enlargement to the original.

Venturi Valve - has a reduced opening and is well streamlined to reduce pressure loss. In some ways similar to a crossover.

Vertical Pattern - in which the body ends are in line with each other, for installation in a vertical position.

Vertical Pattern Check Valve - a check valve design in which the body ends are in line with each other, for installation in a vertical position; compare with Angle Pattern Check Valve and Horizontal Pattern Check Valve.

Vessel - a container in which materials are processed, treated, or stored; for example, pressure vessels, reactor vessels, agitator vessels, and storage vessels (tanks).

VF - Valve, Butterfly VG - Valve, Gate VGO - Vacuum Gas Oil VHAP - Volatile Hazardous Air Pollutants Vibration Severity - the root-mean-square (RMS) value of the vibration velocity. Vicker’s Diamond Pyramid Method - this test is not suitable for measuring hardness of hard

materials. The drawback of the Brinell hardness testing is eliminated in this machine by using a diamond square-based pyramid which does not readily deform and gives geometrically a similar impression under different loads. It employs a diamond pyramid indentor under varying loads from 5 to 120 kg. Vicker’s test is the most accurate method in which a pointed diamond is pushed perpendicularly into the surface by a standard load. The rate and duration of the loading are controlled by a piston and dashpot of oil. The difference, however, between the Vicker’s Diamond Pyramid method and Brinell Hardness Method is that the former gives a square impression at the surface while the latter gives a circular impression. It is easier to make an accurate measurement with a microscope across the corners of the square impression, than with the circular Brinell impression on hard materials. The apex angle of a diamond pyramid used in Vickers’s hardness tester is 136 degrees. Vicker’s method can be used for exceedingly thin materials. The indentor gives geometrically similar impressions with different loads.

Vicker’s Hardness Test - Vicker’s Hardness Test - in this teat a diamond indenter is used in the form of a square based

pyramid. Vickers Hardness - see Diamond Pyramid Hardness Vickers Hardness Number - a number equal to 0.927 p. where p denotes the yield pressure, the

area on which it acts being 0.927 times that of the surface area of the contacting faces. The pyramidal indenter is square-based and the opposite faces contain an angle of 135 degrees. The Vickers and Brinell hardness numbers for a given load are nearly equal; abbreviated VHN.

Vickers’ Diamond Hardness Tester - a small impression machine, which is capable of testing very hard metals, finished components and very thin sheets. The diamond is similar to that used in the diamond pyramid hardness test. The duration of application of the load is controlled automatically, being always applied and removed in exactly the same manner. This machine can also be used with a ball indenter for the Brinell hardness test.

Victaulic Coupling - a development in which a groove is cut around each end of pipe instead of the usual threads; two ends of pipe are then lined up and a rubber ring is fitted around the joint; two semicircular bands, forming a sleeve, are placed around the ring and are drawn together with two bolts, which have a ridge on both edges to fit into the groove of the pipe; as the bolts are tightened, the rubber ring is

compressed, making a watertight joint, while the ridges fitting in the grooves make it strong mechanically.

Virgin - describes thermoplastic resins that have no "regrind" in the processing mix. Sometimes mistakenly interchanged with "Natural."

Virgin TFE - see Teflon Virtual Leak - an "apparent" leak in a vacuum system that is traceable, in fact, to some internal

(and often accidental) release of occluded and/or absorbed gases. Example: An undetected blister in a fused joint may eventually break down in a vacuum and suddenly (or slowly) release its entrapped air, thereby indicating a "leak".

Viscosity - Viscosity - 1) the internal friction of a fluid which makes it resist flowing past a solid surface; 2) a

measure of the resistance of a fluid to flow, caused by internal friction which results in different rates of flow in different parts of the liquid.

Viscosity - a measure of the internal friction or resistance of a fluid to flow. Viscosity - measure of the internal friction of a fluid or its resistance to flow. Viscosity - the internal friction due to molecular cohesion in a field; the resistance to the sliding

motion of adjacent layers of a fluid when in motion. Viscosity - the property of fluids and plastic solids by which they resist an instantaneous change

of shape, i.e. resistance to flow. Viscosity - the resistance of a fluid to flow, due to the mutual adherence of its molecules. A

measure of a liquid's resistance to flow. Several viscosity scales are used depending on the type of oil being measured.

Viscosity - the resistance of a fluid to flow. Molasses has a higher viscosity than water. Viscosity Index - a measure of the viscosity-temperature characteristics of a fluid as referred to

that of two arbitrary reference fluids. Viscosity, Kinematic - the absolute viscosity divided by the density of the fluid. It is usually

expressed in centistokes. Viscous - having a thick, sticky consistency between sold and liquid. Viton A - a fluorocarbon rubber by E.I. du Pont de Nemours co. Viton® - Viton® - a fluorinated elastomer, used in making O-rings and other seals. Viton® is a trade mark

of DuPont Dow Elastomers. Viton® - a non-metallic material used as valve trim. It is an elastomer also known as Fluorel,

FKM, and fluorocarbon. It has good abrasion and tear resistance and resilience, but poor compression-set resistance. It is used for butterfly valve seats and liners and for diaphragm valve diaphragms.

Viton® - a trademarked fluoroelastomer used for bonnet, gate, poppet, and other seals. It can be used for 250°C continuous service, and is useful for ultra-high vacuum systems.

VML - Vendor Master List VN - Valve, Needle VOC - Volatile Organic Compounds VOD - Vacuum Oxygen Decarburized Void - Void - 1) a hollow formed within a molding, especially at thick sections; 2) a defect lowering a

product’s strength by concentrating stress. Void - the absence of material or an area devoid of materials where not intended. Volatile Organic Compound (VOC) - Volatile Organic Compound (VOC) - organic liquid which vaporizes at room temperature. Often

abbreviated VOC. Used as solvent and washing or cleaning agent. Volatile Organic Compounds - loosely defined as carbon-containing compounds that exist as a

toxic gas at ambient pressure and temperature. They are organic compounds, excluding methane and ethane, which contain many hydrocarbons, oxygenated compounds and compounds containing sulfur. VOCs react with nitrogen oxides and sunlight.

Volatilization - the transition of either a liquid or a solid directly into the vapor state. In the case of a liquid, this transition is called evaporation, while in the case of a solid, it is termed sublimation.

Volt - a unit of electromotive force which when steadily applied to a conductor whose resistance is one ohm will produce a current of one ampere.

Voltage Regulation - in welding, an automatic electrical control device used for regulating voltage.

Volume Change - a change in the volume of a seal as a result of immersion in a fluid expressed as a percentage of the original volume.

Volume Flow Rate (Q) - calculated by multiplying the cross-sectional area of the pipe or conduit times the average velocity of the fluid. NOTE: pipe must be full of the measured fluid.

Volume of Flow - the quantity of fluid that passes a certain point in a unit of time. The volume of flow is usually expressed in gallons per minute for liquids and cubic feet per minute for gases.

Volume Swell - an increase in physical size caused by the swelling action of a liquid. VP - Valve, Plug VPI - Vapor Phase Inhibitor VS - Valve, Special VSDS - Variable Speed Drive System VSM - Vertical Support Member VT - Valve, Globe VTC - Vendor To Confirm / Complete VTI - Visual Thread Inspection Vulcanize - Vulcanize - a chemical reaction of sulfur (or other vulcanizing agent) with rubber or plastic to

cause cross-linking of the polymer chains; it increases strength and resiliency of the polymer; also known as Cure.

Vulcanize - a thermo-setting reaction involving the use of heat and pressure, resulting in greatly increased strength and elasticity of rubber-like materials.

Vulcanize - to treat natural or artificial rubber with sulfur at high temperatures to harden it and increase its elasticity.

Vulcanizing - producing a hard, durable, flexible rubber product by steam curing a plasticized mixture of natural rubber, synthetic elastomers and certain chemicals.

Vulcanizing Agent - a material which produces vulcanization of an elastomer.

W - 1) Tungsten; 2) Witness; 3) Water WAD - Weeks After Delivery WAF - Wafer Wafer Body - Wafer Body - a body whose end surfaces mate with the pipeline flanges. It is located and

clamped between the piping flanges by long bolts extending from flange to flange. A wafer body is also called a flangeless body.

Wafer Body - a thin annular section body whose end surfaces are located and clamped between the piping flanges by bolts extending from flange to flange.

Wafer Body - a valve body that does not have “ends”, but is held in place between two flanges by the flange studs.

Wafer Check Valve - a check valve design featuring two spring-loaded flow control elements and a wafer-style body.

Wafer Design - the construction of wafer design valves allows them to be ‘sandwiched’ between flanged sections of pipeline. The benefit is lower bolting requirements. Typically used with certain butterfly and check valves.

Wafer Lugged Body - a thin annular section body whose end surfaces mount between the pipeline flanges, or may be attached to the end of a pipeline without any additional flange or retaining parts, using either through bolting and/or tapped holes.

Wafer Valve - a valve for clamping between pipe flanges using through bolting; also called Solid Ring Valve.

WAFO - Weeks After Firm Order Waist - the center portion of a vessel or container that has a smaller cross section than the

adjacent areas. Wall Ratio - ratio of the outside radius of a tube or jacket to the inside radius, or ratio of the

corresponding diameters. Wall Thickness - the thickness of the wall of the pressure vessel or valve. For steel valves,

minimum thickness requirements are defined in ASME B16.34, API 600, and API 602.

Warpage - the action, process, or result of twisting or turning out of shape. Warped Casting - undesirable deformation in a casting is called warping. Warpage may occur

during or after solidification. Large and thin sections are particularly prone to warpage. Warpage in a casting occurs a) due to faulty design, b) absence of directional solidification, c) poor core strength, and d) non-provision of camber allowance. A warped casting can be straightened wherever the shape permits and where the metal of the casting is not brittle.

Warranty - an assurance that, at the risk of voiding the original contract, all statements and claims made in writing by the seller to the buyer are, in fact, as stated.

Washer - Washer - 1) a flat ring of rubber or metal inserted at a joint for keeping a joint or nut secure, or to

tighten and prevent leakage; 2) a similar ring placed under the head of a screw to disburse its pressure.

Washer - a flattened, ring-shaped device used to improve the tightness of a screw fastener. Washer - a ring shaped component used to distribute a fastener's holding force, insulate or

cushion a nut or bolthead from its baring surface, lock a nut in place, or improve tightness of a bolted joint.

Washer - a small metal device under the head or nut of a bolt or screw to spread the crushing force over a larger contact area. Washers are of two basic types: a cut washer is round with a hole in the center and is manufactured by stamping out of metal strip, and a plate washer is a square metal plate with a hole. A beveled washer is steel, which is tapered on one side so that a bolt or rod can pass through it at an angle but still have full bearing of the nut against the retaining surface. A lock washer is one which has been cut through, and the cut edges twisted in opposite directions to provide further “biting” power into the surface of the material as well as the bottom of the tension between the fastener and the parent material.

Washout Valve - refers to a valve in a pipeline or a dam which can be opened occasionally to clear out sediment.

Wastes - material produced as a by-product of an industrial operation for which there is no

economic demand and which must be disposed of or recycled. WAT - Weeks After Test / Process Water Hammer - Water Hammer - 1) a sudden increase in pressure of water due to an instantaneous conversion

of momentum to pressure; 2) a series of shocks, sounding like hammer blows, caused by suddenly reducing fluid flow velocity in a pipe.

Water Hammer - a phenomenon that occurs when the velocity of a fluid in a pipeline is abruptly decreased (such as when a valve is rapidly closed). At the point of fluid velocity decrease there is a corresponding increase in fluid pressure that is reflected back upstream as a pressure wave, causing noise and vibration. If the initial pressure is great enough, the pipe may burst.

Water Hammer - a sharp hammer-like blow from a steep fronted pressure wave in fluid, caused by the sudden stoppage of flow in a long pipe when a valve Is closed sufficiently rapidly.

Water Hammer - a term applied to the noise made by a fast-moving liquid inside a pipe when its flow is abruptly shut off.

Water Hammer - the phenomena of oscillations in the pressure of water in a closed conduit, resulting from checking the flow. Momentary pressure, greatly in excess of the normal static pressure, may be produced in this manner. It occurs in turbines, pumps and such other machines when the velocity of flowing fluid is suddenly changed, such as may take place when a valve rapidly closes or opens. When it happens, shock pressure waves are set up, which damage control devices.

Water Hammer - vibration in a fluid system due to a rapid decrease in the velocity of a liquid from closing a valve.

Water Hammer - water hammer is caused because of sudden stoppage of water flow in a pipe. Sudden stoppage produces a pressure wave, which moves upstream with velocity of sound in the medium, which is reflected back and fourth until dissipated by friction and imperfect elasticity.

Water Oil Gas (WOG) - Water Oil Gas (WOG) - a number along with the letters WOG on a valve indicate the allowable

working pressure of the valve when used at ambient temperatures; abbreviated WOG; also called Cold Working Pressure (CWP); see Cold Working Pressure.

Water Oil Gas (WOG) - a rating designation generally used for small valves chiefly in low ratings. Indicates maximum working pressure at ambient + 32° F to +100° F; also called Nonshock Rating.

Water Soluble Binders - molasses and dextrine are the water soluble binders added to core sands. Increased moisture content of water-soluble binders produces a higher tensile strength and edge hardness in baked cores. A water-soluble binder air hardens rapidly and resists core sagging during handling.

Waterblasting - similar to Sandblasting but using a high velocity stream of water (5,000 to 10,000 psi, depending on use) to remove paint or other coating materials, rust, and for general cleaning purposes. For special purposes such as smoothing concrete surfaces, sand is added to the water.

Way - a body opening in a plug valve; compare with Port. Waybill - a list that gives details of goods being carried by a commercial vehicle. WB - Welded Bonnet WC - 1) Water, Corrosive (CO2 content); 2) Water, process (corrosive) WCB - 1) Cast Carbon Steel; 2) The ASTM standard also has a WCA and a WCC. For low-

temperature service there are LCA, LCB and LCC. There are slight variations in the compositional and strength requirements between each alloy in the series. ASTM/ASME A216 has three grades, namely WCA, WCB & WCC for carbon steel castings with slight variations in chemical/mechanical values. The W or L refer to Welding or Low Temperature, C for Casting, and the A, B and C for the position in the series. ASTM A216 is entitled Steel Castings, Carbon, Suitable for Fusion Welding, for High Temperature Service. ASTM A352 is Steel Castings, Ferritic and Martensitic, for pressure containing parts, Suitable for Low Temperature Service.

WD - Water, Disposal (corrosive) WE - Welded End

Wear - Wear - progressive deterioration of a solid surface due to abrasive or adhesive action resulting

from relative motion between the surface and another part or a loose solid substance.

Wear - the process of losing material from two surfaces that have rubbed against one another. Wear Oxidation - see Fretting Weatherometer - a device used to subject articles and finishes to accelerated weathering

conditions; for example, a rich ultraviolet source, water spray, or salt water. Wedge - Wedge - a flow control element of a gate valve which is wedge-shaped in cross-section. Wedge - Gate Wedge - in ultrasonic testing, a device which directs waves of ultrasonic energy into the test

piece at an angle. Wedge - the component of a wedge gate valve, in the form of solid or split wedge, attached to the

stem, and on which the wedge faces are machined. Wedge Bush - in a wedge gate valve, the bush secured in the wedge and threaded internally to

engage the actuating thread of the stem of an inside screw, non rising stem valve. Wedge Faces - in a wedge gate valve, machined faces which make contact with the body seats

when the valve is closed. They may be machined on the wedges themselves or on the wedge facing rings.

Wedge Facing Rings - in a wedge gate valve, rings of different material from the wedges and secured to them, on which the wedges faces are machined.

Wedge Gate - the flow control element of a gate valve that is wedge-shaped in cross-section for use with body seating surfaces that are inclined to the stem centerline. There are three designs available: solid, flex, and split.

Wedge Gate Valve - Wedge Gate Valve - a gate valve in which closure is effected by the wedge action between the

gate and the body seats, the gate being either solid or cored on one piece or in two pieces.

Wedge Gate Valve - a valve in which closure is effected by the wedge action between the gate and the body seats. Wedge gate valves may take the following forms: a) solid wedge - in which the gate is in one piece, either solid or cored. b) split wedge - in which the gate is in two pieces.

Wedge Nut - in a wedge gate valve, the nut retained in the wedge and threaded internally to engage the actuating thread of the stem of an inside screw, non-rising stem valve.

Wedge Ring - on some butterfly valves, a metal band wedged between the valve body and retainer ring by setscrews, used to lock the seat and retainer ring in position.

Weep - a term usually applied to a minute leak in a boiler joint which forms droplets (or tears) of water very slowly.

Weight - the loading medium of the valve Weight (WT) - Weight (WT) - the force with which a body is attracted by gravity. The Newton is the unit force in

this Standard. Weight Casing - that component, attached to the cover, which forms part of the load and carries

the loading weights. Weight Casing Bolting - comprises bolts and nuts used for the cover/weight casing connection. Weight Casing Cover Flange - the flange on the weight casing to which the cover flange is

connected. Weight Loaded Regulator - a pressure-regulator valve for pressure vessels or flow systems;

the regulator is preloaded by counterbalancing weights to open (or close) at the upper (or lower) limit of a preset pressure range.

Weight Test - different metals have different densities (weight per unit volume). Sometimes the density of a material serves as a useful test to differentiate one metal from another, especially in cases where both possess similar color or luster. This comparison is made on the basis of the specific gravity of materials. Specific gravity is the ratio of weight of a substance compared to the weight of an equal volume of water, taken as unity. To find the specific gravity of metal we have to find the volume and

measure the weight of the metal to be identified. Then, either its specific gravity or density is calculated and a comparison is made to distinguish or identify it. For this purpose, knowledge of densities and specific gravities is essential.

Weights - plateweights Weir Body - a body having a raised contour contacted by a diaphragm to shut off fluid flow. Weir Diaphragm Valve - Weir Diaphragm Valve - a body having a raised contour contacted by a diaphragm to shut off

fluid flow. Weir Diaphragm Valve - a diaphragm valve featuring a dam, or weir, formed in the body across

the fluid flow path. This design reduces diaphragm flexing, but increases flow resistance.

Weld Crack - a crack at any portion of the weld metal. Weld Decay - a form of pitting corrosion which takes place in heat affected zones adjacent to

welds in non-stabilized stainless steels. It can be overcome by small additions of titanium or niobium, which prevent separation of chromium carbides.

Weld Ends - valve end connections which have been prepared for welding to the line pipe or other fittings. May be butt weld (BWE), or socket weld (SWE).

Weld Gauge - a device used to check the shape and size of welds. Weld Joint - a joint between two metals or plastics, made by fusion or diffusion to create

interatomic bonding between the parts joined. Weld Line - a line on the surface of a molding where melt fronts have met, but fused poorly. Weld Metal - Weld Metal - that portion of a weldment that has been molten during welding. Weld Metal - the metal in the fusion zone of a welded joint. Weld Overlay - produced by weld depositing a dissimilar material on a base metal surface; also

called Surfacing. Weld Testing - the principal means of examining or testing for the quality of a weld. In addition

to physical testing and examination, the following non-destructive testing methods are available:

- Dye Penetrant Testing - a means whereby a dye is place on the weld and subsequently rubbed off. Minute cracks and voids, which are penetrated by the dye, can be seen.

- Magnetic Particle Testing - a means of testing by applying finely ground iron particles, then brushing them away. By means of a magnetic detection system, remaining particles in minute cracks and other defects can be determined.

- Ultrasonic Testing - a means whereby high-frequency sound waves are directed at the joint and reflected back to a recorder by a transponder. The weld area can be scanned with the results displayed on an oscilloscope, which will indicate voids or other defects in the weld.

- X-Ray Inspection - a means whereby an X-ray film is made of welded joints such that voids or other defects in the weld show up on the film.

Weldability - Weldability - the ability of a material to be welded together by the application of heat and / or

pressure. Weldability - the capacity of a metal to be welded under suitable conditions. Welded Joints - the two basic types of welds are the butt weld, where the weld metal fills the

space between parts to be joined, and the fillet weld, where a triangular (fillet-like) weld is placed in the corner between the parts. The value of such a weld is limited by the stress at the throat (plane of minimum cross section). A plug weld is a side-to-side joining of plates by filling a hole in one plate with weld metal that also fuses to the plate below; if such a hole is elongated, it is called a slot weld. A tack weld, or spot weld, is a very short length of weld to temporarily join two pieces in such a way as to hold them in position for further welding.

Welder - a person who performs welding operations. Welder Qualification Record (WQR) - like a Welding Procedure Specification record of the skill

test performed by each qualified tradesman to meet code requirements. Each WQR will reference the Procedure Qualification Record used and will attach the test results obtained. Welders that made an approved Procedure Qualification Record are qualified by that Procedure Qualification Record if they have a WQR derived

from that result on file. Welding - Welding - 1) to join two pieces of metal by heating them to the melting point and fusing them

together, or by applying pressure alone, producing a stronger joint than soldering; 2) joining two or more pieces of metal by applying heat and / or pressure with or without filler metal, to produce a union through localized fusion of the substrates and solidification across the interface.

Welding - a process of joining metals by heating until they are fused together, or by heating and applying pressure until there is a plastic joining action. Filler metal may or may not be used.

Welding - producing a coherent bond between two similar or dissimilar metals by heating the joint, with or without pressure, and with or without filler metal, to a temperature at or above their melting point.

Welding - the coalescence of metal by heating to a suitable temperature with or without the application of pressure or filler metal.

Welding - the joining or fusion of pieces of metal by raising the temperature at the joint to make metal plastic so that the pieces can be joined or fused together.

Welding - the process of joining metals by heating them to a suitable temperature with or without the application of pressure and with or without the use of filler metal. The filler metal used in welding has approximately the same melting point as those of the metals or workpieces to be joined, or a little lower, but always above 430° C.

Welding - the process of jointing metal parts by causing their fusion (melting) by the application of heat and pressure. A filler material is often used in welding. The filler material sets in the joints on cooling.

Welding - to join metals by applying sufficient heat to melt and fuse two pieces together. Welding Current - the current through the welding circuit during a welding operation. Welding Fluxes - used to prevent oxidation of a weld Welding Generator - any electrical current generating equipment used for welding. Welding Goggles - goggles used by a welder during a welding operation to protect his eyes. Welding Machine - equipment used to carry out welding operations. Welding Procedure - Welding Procedure - the detailed methods and procedures used to perform a perfect welding

operation. Welding Procedure - the detailed methods which are followed in producing any particular welded

structure. Welding Procedure Proposal Sheet (WPPS) - a draft form of Welding Procedure Specification

prepared for the purpose of client approval of a proposed Procedure Qualification Record for testing or client review of production Welding Procedure Specification.

Welding Procedure Specification (WPS) - sets out all joint preparation, welding and post weld controls required by the production welder to make and repeat a specific weld joint. It is issued by a competent welding supervisor or engineer using conditions within code allowable variations from the parent Procedure Qualification Record named on the WPS. Each welder works from a specific WPS and no quality critical weld can be produced to code without reference to a WPS.

Welding Rod - Welding Rod - a filler metal or wire used in welding. Welding Rod - filler metal in the form of a wire or rod; in electric welding the electrode supplies

the filler metal to the joint. Welding Rod - used for filler metal Welding Symbols - symbols used on drawings to indicated various types of welded joints. Welding Tip - a replaceable nozzle for a gas torch used in welding. Welding Torch - Welding Torch - a gas-mixing and burning tool for the welding of metal. Welding Torch - equipment used in gas welding in which mixing of gases takes place and burning

occurs at the tip; also know as Welding Blowpipe. Welding Transformer - A.C. equipment used for regulating voltage and current in welding. Weldment -

Weldment - a structure or assembly whose parts are joined together by welding. Weldment - a welded assembly Weldment - an assembly or structural part whose component parts are joined by welding. Weldment - that portion of a component on which welding has been performed. A weldment

includes the weld metal, the heat affected zone (HAZ), and the base metal. Wellhead - some use the term "Wellhead" as a description of a location or function rather than a

specific item of equipment. See also Production Wellhead. API6A says that a wellhead is all permanent equipment between the uppermost portion of the surface casing and the tubing head adapter connection.

Wellhead Valve - Wellhead Valve - a valve, usually a plug or gate valve, used to isolate the flow of oil or gas at the

takeoff from an oil or gas well. Wellhead Valve - used to isolate the flow of oil or gas at the takeoff from an oil or gas well. The

design is usually a plug or gate valve. Wet and Dry Bulb Thermometer - see Psychrometer Wet Bulb Thermometer - Wet Bulb Thermometer - a thermometer having its bulb covered with a wet cloth. The water

evaporates to cool the wet bulb and by comparing its temperature to a dry bulb thermometer, the amount of water vapor in the air can be determined.

Wet Bulb Thermometer - a thermometer having the bulb covered with a cloth, usually muslin or cambric, saturated with water.

Wet Film Thickness (WFT) - the thickness, in microns, of the wet coating film. Wet Grinding - 1) the milling of materials in water or other liquid; 2) the practice of applying a

coolant to the work and the wheel to facilitate the grinding process. Wet Welding - welding directly carried out in water using water proof stick electrodes. Wetted Surface - if a surface will ever be in contact with pressurized well fluid it is a wetted

surface. WF - 1) Water, Fire, seawater; 2) Water, Fire, raw, corrosive / non corrosive WFMT - Wet Florescent magnetic Particle Test WFT - Wet Film Thickness WG - Water / Glycol mixture & glycol WH - Water, Hot (domestic plumbing) WHCP - Wellhead Control Panel White Cast Iron - White Cast Iron - cast iron in which substantially all of the carbon is in solution and in the

combined form. The metal has a white fracture. White Cast Iron - iron containing carbon in the combined form. Generally it contains lesser

carbon than gray cast iron. White Cast Iron - it contains carbon in the combined form (cementite or Fe2C) which makes the

metal hard and brittle; the absence of graphite gives the fracture a white color. White Cast Iron - pig iron or cast iron in which all the carbon is present in the form of cementite.

White iron has a white crystalline fracture, and is hard and brittle. White Cast Iron - see Cast Iron White Cast Iron - when cast iron is melted and then rapidly cooled, it becomes very hard and

brittle and is known as white cast iron. The composition of white cast iron is 94% iron, 0.5% graphite, 3% carbon in combined form and remainder other impurities. The color of this variety of cast iron is white because the carbon is mostly in the combined form. It is hard, brittle and cannot be machined. Its fluidity is low and cannot be molded. It is generally used for inferior castings and does not rust as much as the grey variety.

White Cast Iron - white cast iron is identified due to a white-colored fracture, which is due to the mechanical mixture of ferrite and cementite. Cementite gives white fracture and is a very hard constituent. Mostly white cast irons contain less than 3.0% carbon and a lesser amount of silicon. The rapid rate of cooling also helps in the production of white cast iron. The properties of white cast iron can be predicted on the basis of its microstructure. Cementite is the hardest phase in the alloys of iron and carbon. It appears in white cast iron in large amount as a continuous inter-dendritic network.

It makes the cast iron very hard, strong and abrasion resistant. On the other hand, it is difficult to machine, thus its usefulness is distinctly limited. White cast iron is generally used for dies and extrusion nozzles, grinding mills, balls and liners, wear plates, etc.

White Metal - White Metal - a tin-based alloy used for lining bearings. White Metal - usually denotes a tin based alloy containing varying amounts of lead, copper and

antimony, used for bearings, domestic articles and small castings. The term is sometimes also applied to alloys in which lead is the principal metal; also called Anti-Friction Metal or Bearing Metal.

Whitworth Screw Thread - a British standard screw threaded characterized by a 55 degree V form with rounded crests and roots.

WHRP - Wellhead Riser Platform WI - Water, de-oxygenated seawater for Injection Width - seal cross section or thickness Wildcat Well - an exploratory oil well Win - to extract metals, minerals, etc. from ore Winding - a coil of conducting wire in an electric motor. Windup - the twisting of a shaft under a torsional load, usually resulting in vibration and other

undesirable effects as the shaft relaxes. Wing Valve - valve that can be used to shut off well flow, located on the Christmas tree but not

on the vertical run. Wiper Ring - a ring employed to remove excess fluid, mud, etc., from a reciprocating member

before it reaches the packings. Wire Brushes - used for general cleaning of weld prior to welding and removal of rust, etc. It

also removes slag after welding. Wire Draw - to draw out metal into wire Wire Drawing - the erosion of a valve seat under high velocity flow in which thin wire-like gullies

are eroded away. Witness Point - a mandatory inspection notification point. The buyer is provided with the

contractual notice period. Work will be held up to the end of the notification period and may then proceed with or without buyer inspection.

WL - Wafer Lug WM - Weld Metal WN - Weld Neck WNFL - Welding Neck Flange WO - 1) Water; Oily; 2) Water, process / Oily, non corrosive; 3) Wrench Operated WOG - Water, Oil and Gas; see CWP WOG Rating - the operating pressure rating of a valve as identified by valve markings for Water,

Oil or Gas. WOL - Weldolet Wood Flour - up to 1% of ground hardwood cellulose is added to core sands to decrease veining

and to increase collapsibility of cores and flowability of the sand for making cores. Wood Product Binders - natural resin, ligrin and sulphite binders are known as wood product

binders. Ligrin is a by-product of paper industry. The percentage of wood products binders varies from 0.5 to 1.5% in core sands. These binders contribute towards green and dry strength of core sand.

Work - the transference of energy from one body or system to another. That which is accomplished by a force acting through a distance.

Work Hardening - Work Hardening - an increase in strength and hardness of metals which is produced by making

them do work, such as resisting or forming. It is most pronounced when cold working metals such as iron, cooper, aluminum and nickel, which do not recrystallize at room temperature.

Work Hardening - refers to the increase in the hardness and strength of a metal produced by cold plastic deformation or mechanical working.

Work Hardening - see Strain Hardening

Work Hardening - the hardening effect given to a metal by cold working. Work Life - the period of time a resin or an adhesive will remain usable after it is mixed with a

catalyst and other ingredients; also known as Pot Life and Working Life. Working Life - see Work Life Working Load - Working Load - the maximum load that any structural member is designed to support. Working Load - the mean ordinary load to which a structure or mechanism is subjected. Workpiece - an object that is being manufactured. Works - a factory Worm - Worm - a shaft having at least one complete spiral tooth around the pitch surface, and used as

the driving member for a worm gear or worm wheel. Worm - a shank having at least one complete tooth (thread) around the pitch surface; the driver

of a worm gear. Worm - the spiral thread of a screw Worm and Worm Wheel - a gear arrangement to transfer motion in a direction at right angle. Worm Gear - Worm Gear - a gear set in which the input shaft is offset from and perpendicular to the output

shaft, and the driving gear is very small and perpendicular to the driven gear. Worm gear operators are used on ball valves.

Worm Gear - a gear with teeth cut on an angle so it can be driven by a worm; it is used to transmit power and motion between two nonparallel, nonintersecting shafts.

Worm Gear - a gear with teeth cut on an angle to be driven by a worm; used to connect non-parallel, non-intersecting shafts.

Worm Gear - an arrangement of a toothed wheel worked by a revolving shaft with a spiral thread.Worm Gear Operator - a gear operator that uses a worm gear set. Worm Wheel - Worm Wheel - a gear wheel with curved teeth that mesh with a worm; it is usually used to

transmit power and motion from the worm shaft to a nonintersecting shaft whose axis is at right angles to the worm shaft.

Worm Wheel - a gear wheel with curved teeth that meshes with a worm. WP - 1) Working Pressure; 2) Water, Potable WPPS - Welding Procedure Proposal Sheet WPQR - Welding Procedure Qualification Results WPQT - Welding Procedure Qualification Test WPS - Welding Procedure Specification WPTD - Weeks Prior To Delivery WPTP - Weeks Prior To Production WPTT - Weeks Prior To Test / Process WQ - 1) Welder Qualifications; 2) Water, raw / wash, corrosive WQR - Welder Qualification Record WR - Water, Raw / wash, non corrosive, (fresh) Wraparound Liner - in a butterfly valve body, a liner extending around the end faces of the wafer

body to form a gasket seal with the pipe flanges. The liner may cover all or part of the flange contact area of the wafer body.

Wrench - Wrench - a device for manually operating a plug or ball valve consisting of a length of pipe or bar

with one end prepared to fit the valve stem. Wrench - a device for manually operating a plug or ball valve, consisting of a length of pipe or bar

with one end prepared to fit the valve stem. Wrench - a lever, which may be integral with or separate from the stem or plug, by which a valve

is manually operated; sometimes called a Key. Wrench - the combination of a couple and a force which is parallel to the torque exerted by the

couple. Wrench Handle - that component which is attached to, or inserted in, the wrench head. Wrench Head - that component which is attached direct to the ball shank head or stem head.

Wrench Head Bolt - a bolt with a square or hexagonal head designed to be gripped between the jaws of a wrench.

Wrench Retainer - that component which retains the wrench or wrench head on the stem or ball shank.

Wringing Fit - a fit of zero-to-negative allowance. Written Practice - the specific requirements which define the employer’s procedure for the

qualification and certification of (non-destructive testing) personnel. Wrought - Wrought - 1) to beat out or shape metal by hammering; 2) metal in the solid condition that is

formed to a desired shape by working (rolling, extruding, forging, etc.), usually at an elevated temperature.

Wrought - describes products or materials made via forging. A wrought structure is said to contain no cast dendritic structure.

Wrought Alloy - a metallic material that has been plastically deformed, hot or cold, after casting to produce its final shape or an intermediate semifinished product.

Wrought Iron - Wrought Iron - a mechanical mixture of highly refined metallic iron and a small amount of slag. It

is resistant to corrosion in ordinary atmospheres and welds readily. Wrought Iron - a tough, malleable form of iron with very low carbon content. It has small amounts

of slag as evenly distributed threads or fibers that make it tough and ductile. Wrought Iron - a very malleable pure iron, having so low a carbon content that it cannot be

hardened by quenching. Wrought Iron - it is nearly pure iron, with only 0.1 or 0.2% carbon and less than 0.5% of all

impurities. It is made by melting cast iron on a bed of iron oxide in a furnace in which the flame is reflected by the roof onto the material to be heated. As the molten cast iron is stirred, the iron oxide oxidizes the dissolved carbon monoxide, and the sulphur, phosphorus and silicon are removed, the melting point of the iron rises and the mass becomes pasty. It is then taken out of the furnace and beaten under steam hammers to force out the slag. Wrought iron is a strong, tough metal that can be readily welded and forged. In past years it was extensively used for making chains, wires and similar objects. It has now been largely displaced by mild steel.

Wrought Steel - a large variety of wrought steels are available. Mechanical properties can be controlled by the composition and heat treatment. It may be forged, swaged, drawn, welded and machined. It finds many applications in engineering.

WS - 1) Water, Sea, untreated; 2) Wrought Steel WSP - Working Steam Pressure WT - 1) Water, Treated (de-ionized); 2) Wall Thickness WW - Water Waste, sewage WWP - Working Water Pressure WWS - Wire Wrapped Screen Wye - a pipe branching off a straight main run at an angle of 45 degrees; also known as Y and

Yoke. Wye Fitting - see Y Fitting

X - Ray Radiography - in this procedure, x-rays are emitted from an x-ray tube. The portion of the metal where the defects are suspected is exposed to x-rays from a x-ray tube. A cassette containing an x-ray film is placed behind and in contact with the metal, perpendicular to the rays. As soon as the tube is switched on, x-rays are emitted by the x-ray tube which penetrate the metal and affect the x-ray film placed behind the metal. As defects like blowholes, cracks, and porosities are less dense than the solid metal of the casting or forging, they allow the x-rays to pass through it easily. Therefore, the film appears more dark where the defects are in line with the x-ray beam as more x-rays fall on the film. The film developed gives dark and light areas known as a Radiograph. After developing the film, if any defect is present, it can be detected.

X’mas Trees - oil industry term for a wellhead, specifically the top of the wellhead where there is a collection of valves and fittings.

XFR - X-Ray Fluorescence (spectrometer) XLPE - Cross Linked Polyethylene XP - Explosion Proof X-Ray Crystallography - the planes of atoms in crystals act as a diffraction granting to X-rays,

which get scattered by them and provide an accurate means of determine the details of the internal atomic structure. X-ray photographs of metals provide information, which in many cases cannot be obtained by ordinary microscopic methods. The lines produced by an element, or phase, are characteristic; the general pattern makes the crystalline structure to the identified.

X-Rays - penetrating, electromagnetic waves which are similar to light but of much shorter wavelength, and are emitted when high-speed electrons suffer an abrupt loss of energy. Although they are invisible, photographic films, luminescent screens and instruments can detect them. These rays are often used for detecting flaws or causes of failure in metals.

XS - Extra Strong Wall Thickness XV - Isolation Valve XX - Inspection 100% XXS - Double Extra Strong Wall Thickness

Y - Wye Valve, Fitting or Strainer Y Fitting - a pipe fitting with one end subdivided from two openings, usually at a 45 degree angle

to the run of the pipe; also known as Wye Fitting. Y Pattern Globe Valve - a globe valve design in which the stem is inclined at an angle of

approximately 45 degrees from the fluid path. Yield - Yield - refers to the permanent set of a metal when it is stressed beyond its elastic limit. Yield - that stress in a material at which plastic deformation occurs. Yield Point - Yield Point - refers to that point on a stress-strain curve where, for a given material, an increase

in stress causes a permanent deformation; also called Elastic Limit. Yield Point - the first stress in a material usually less than the maximum attainable stress, at

which an increase in strain occurs without an increase in stress. Only certain metals exhibit a yield point. If there is a decrease in stress after yielding, a distinction may be made between upper and lower yield points.

Yield Point - the lowest stress at which strain increases without increase in stress. Yield Point - the stress at which a substantial amount of plastic deformation takes place under

constant or reduced load. This sudden yielding is a characteristic of iron and annealed steels.

Yield Point - the stress at which appreciable elongation occurs without increase in stress. Yield Point - the unit stress at which the deformation first increases markedly without any

increase in the applied load. It is always above the proportional limit. Yield Strength - Yield Strength - the limiting stress beyond which a material will sustain permanent deformation. Yield Strength - the stress at which a material exhibits a specified deviation from the

proportionality of stress to strain. The deviation is expressed in terms of strain by either the offset method (usually at a strain of 0.5%) (refer to ASTM A 370).

Yield Strength - the stress at which a material exhibits a specified deviation from proportionality of stress and strain. An offset of.2% is used for many metals.

Yield Strength - the stress at which a material exhibits a specified inciting permanent set. Yield Strength - the stress level above which the pipe will yield/bend/stretch. Yield Strength - the stress level at which material plastically deforms. Yoke - Yoke - a clamp or similar device to embrace and hold two other parts. Yoke - a clamping device to embrace and hold two other parts. Yoke - an extension of a valve bonnet shaped like an inverted “Y”. The top of the yoke holds a

yoke nut and the valve stem passes through it. Yoke - bridge Yoke - that exterior part of an outside screw valve, integral with or separate from the bonnet, in

which the actuating thread of the stem engages, either directly or through a yoke bush or a yoke sleeve; also called Bridge.

Yoke - the exterior part of an outside screw and yoke valve in which the actuating thread of the stem engages either directly or through a bush or through a yoke sleeve. The yoke may be integral with or separate from the bonnet.

Yoke - the exterior part of an outside screw and yoke valve, integral with or separate from the bonnet, in which the actuating thread of the stem engages, either directly or through a yoke bush.

Yoke - the part of gate or globe valve which acts as a bracket to support the top or outer end of the stem and stem bearing.

Yoke Bolting - Yoke Bolting - comprises bolts, stud bolts, studs, set screws and nuts used for yoke and yoke

cap assemblies and for securing the yoke to the bonnet. Yoke Bolting - the bolts, stud bolts, studs, set screws and nuts used for securing a yoke to the

valve bonnet. Yoke Bush - Yoke Bush - a bush secured in a valve yoke and threaded internally to engage the actuating

thread of the stem.

Yoke Bush - a bush secured in the yoke and threaded internally to engage the actuating thread of the stem.

Yoke Bush Key - Yoke Bush Key - a locking device which prevents rotation of the yoke bush in the yoke; also

known as Locking Screw. Yoke Bush Key - see Yoke Locking Screw Yoke Bush Nut - a nut which secures the yoke bush in a valve yoke. Yoke Bushing - Yoke Bushing - Operating Stem Nut Yoke Bushing - see Yoke Nut Yoke Cap - a cap bolted to the yoke to perform a similar function to that of the yoke sleeve

retaining nut. Yoke Locking Screw - a locking device which prevents rotation of the yoke bush the valve yoke;

also called Yoke Bush Key. Yoke Nut - Yoke Nut - an internally threaded nut held in a recess at the top of the yoke through which the

valve stem passes. In gate valves and diaphragm valves the yoke nut is turned, and the stem is translated through it. In globe valves the yoke nut is usually fixed and the stem is turned through it; also called Stem Bushing, Stem Nut, or Yoke Bushing.

Yoke Nut - Stem Nut Yoke Sleeve - a sleeve to which the hand wheel is secured and which is located in the yoke to

engage the actuating thread of the stem. Yoke Sleeve Retaining Nut - a nut to retain the yoke sleeve in the yoke. Young’s Modulus (Modulus of Elasticity) - the ratio of a simple tension stress applied to a

material to the resulting strain parallel to the tension. Young’s Modulus (Modulus of Elasticity) - Young’s Modulus (Modulus of Elasticity) - the ratio of stress to the corresponding strain.

Assuming a material to be perfectly elastic, Young’s modulus would be the stress needed to double the length of a test piece provided that is continued to obey Hooke’s law.

Zero Bevel Gear - a special form of bevel gear having curved teeth with a zero-degree spiral angle.

Zinc (Zn) - Zinc (Zn) - a brittle, bluish-white metallic element used in various alloys and as a corrosion-

resistant coating to galvanize steel. Zinc (Zn) - a hard, silvery metal which is used primarily as a corrosion resistant coating on steel

due to its ease in melting and high resistance to rust. Zn - Zinc Zone - The international method of specifying the probability that a location is made hazardous

by the presence, or potential presence, of flammable concentrations of gases and vapors. NOTE: zone classification has not yet been defined for dusts and flyings.

Zone 0 - classification of a location in which an explosive concentration of a flammable gas or vapor mixture is continuously present or is present for long periods. The area classified as Zone 0, although not specifically defined, is contained within the United States and Canadian classifications of a Division 1 location and constitutes an area with the highest probability that an ignitable mixture is present.

Zone 1 - classification of a location in which an explosive concentration of a flammable or explosive gas or vapor mixture is likely to occur in normal operation. The area classified as Zone 1 is contained within the United States and Canadian classifications of a Division 1 location.

Zone 2 - classification of a location in which an explosive concentration of a flammable or explosive gas or vapor mixture is unlikely to occur in normal operation and, if it does occur, will exist only for a short time. Zone 2 is basically equivalent to the United States and Canadian classifications of a Division 2 location.

Zones - formerly called divisions. A zone is an area of similar probability of the presence and concentration of the potentially explosive mixture. It is part of the area classification. (The other part being the gas group.) Three zones are recognized in the UK: Zone 0 - In which an explosive gas-air mixture is continuously present or present for long periods; Zone 1 - In which an explosive gas-air mixture is likely to occur in normal operation; Zone 2 - In which an explosive gas-air mixture is not likely to occur in normal operation, and if it occurs will exist only for a short time.

ZSC - Limit Switch for Close ZSO - Limit Switch for Open Zyglo Method - a technique for liquid penetrant testing to detect surface flaws in a metal using a

special penetrant that fluoresces when viewed under ultraviolet radiation.