Piping & Tubing

7/27/2019 Piping & Tubing

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WHAT IS PIPING ABOUT..We can say PIPING is about designing, fabricating and constructing lines conveyingFLUIDS.

What is a FLUID?It can be any of the following

a GAS a LIQUID a mixture of GAS and LIQUID a SUSPENSION of small SOLID PARTICLES

inside a LIQUID.

Basic properties of conveyed FLUIDS

FLUID TYPE with particular attention to the CORROSION characteristics theDANGER for HEALTH and the ENVIRONMENT

FLOW RATE PRESSURE TEMPERATURE

What is a PIPELINE?

A PIPELINE conveys a fluid from one given point of the plant usually called INLETpoint of the line, to another part of the plant usually called OUTLET point of the line.A PIPELINE can also connect one PIPELINE to another PIPELINE. PIPELINES can

also discharge the conveyed fluid into the environment (VENTS and DRAIN)

Basic characteristics of a PIPELINE

SIZE (or DIAMETER) WALL THICKNESS TYPE OF JOINTS BETWEEN PIECES welded joints (butt welding / socket

welding)threaded joints flanged joints EXTERNAL FINISHING Painting Insulation QUALITY CHECKS Hydraulic Testing Non Destructive Examination of Joints.

Other characteristics of a PIPELINEROUTING

The routing is how the Pipeline is developed into the space. There are rules and regulations to route a Pipeline according the Good EngineeringPractice Cold Pipelines connecting static objects (something that does not movelike Tanks, Vessels, other Pipelines, Headers) can be straightly routed between theinlet and the outlet point. Cold Pipelines connecting MACHINES that vibrate orrotate may


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Choice of joints: DANGEROUS fluids are conveyed in fully welded pipes, were leakscannot occur. Choice of NDE : For Dangerous Fluids 100% of joints are likely to beX- Ray examined

FLOW RATE Choice of Diameter

For a given flow rate- SMALL DIAMETER means HIGHER VELOCITY of the conveyed fluid - BIG DIAMETER means SLOWER VELOCITY of the conveyed fluid Velocity of fluidsin Pipelines affects- Pressure Losses along the Pipeline Pressure Losses are PROPORTIONAL to thesquare velocity (v 2 )- Vibration of the Pipeline Usual Velocity of Fluids inside pipelines are:

Gas: 20 m/ s - max. 40 / 50 m/ secLiquid: 2 to 4 m/ s - max. 10 m/ sec

TEMPERATURE Choice of MATERIAL

-Steel for High Temperature (Low Alloy Steel Creep Resistant) Calculation of wallTHICKNESS Routing Design and calculation of SUPPORTS (STRESS ANALYSIS)-Hot Lines must be routed properly. Provisions shall be taken so that whentemperature rises from ambient to Operating Temperature the thermal expansion ofPipelines does not generate stresses too high for the pipes to withstand. Applicationof Thermal Insulation -T> 60 C Insulation for Personnel Protection is mandatoryfor all pipeline parts that can be reached by hands.

PRESSURE :

1. Calculation of Wall Thickness2. Choice of the Joint-Low pressure pipelines can be threaded or socket welded-High Pressure pipelines are Butt Welded

1. 4. Extension of NDE of the joints

- Non process Pipelines (For Example Vents and drain lines) mayeven have no tests at all- Low Pressure Pipelines can undergo only the Hydraulic Test-For intermediate pressures a 10% to 50% of joints must beexamined with X- rays-High Pressure Pipelines are usually 100% X- ray examined.

AMERICAN STANDARDS FOR PIPING DESIGNANSI = AMERICAN NATIONAL STANDARDIZATION INSTITUTE

ASME = AMERICAN SOCIETY of MECHANICAL ENGINEERS


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ANSI/ ASME B31.1: POWER PIPINGANSI/ ASME B31.3: PROCESS PIPING

THESE STANDARDS GIVE TECHNICAL RECOMMENDATIONS FOR DESIGNING PIPINGSYSTEM FOR POWER PLANTS AND CHEMICAL PLANTS THEY CONTAINS FORMULASTO CALCULATE THE MINIMUM THICKNESS OF PIPELINES THEY CONTAINSORMULAS TO CALCULATE THE EXTRA THICKNESS THAT A PIPE MUST HAVE WHEN ABRANCH IS CUT INTO IT. THEY CONTAINS REGULATIONS FOR STRESS ANALYSISTHEY ONTAINS TABLES THAT GIVE MAXIMUM ALLOWABLE STRESS FOR METALLICMATERIALS ACCEPTED BY ANSI FOR PIPELINE CONSTRUCTION DEPENDING ONTEMPERATURES.

STANDARD MATERIALS FOR PIPING

ASTM = AMERICAN SOCIETY for TESTING MATERIALS

ASTM developed a collection of documents called MATERIAL SPECIFICATIONS for standardizingmaterials of large use in the INDUSTRY. Specifications starting with A are for STEEL.Specifications starting with B are for non- ferrous alloys (Bronze, Brass, Copper Nickel alloys,

Aluminum alloys and so on). Specifications starting with D are for plastic material, as PVC. AnASTM Specification does not only specify the basic CHEMICAL COMPOSITION of material, butalso the PROCESS through which the material is shaped into the final product. This is why for agiven base material SEAMLESS PIPE have a specification, WELDED PIPE have anotherspecification WROUGHT FITTINGS have another specification, FORGED FITTINGS have anotherspecification, large VALVE bodies (normally CAST) have another specification

CARBON STEEL

Steel is basically a solution of carbon (C) into iron (Fe). The presence of carbon into the crystalstructure of the iron improve very much the mechanical characteristics of the iron alone. Carbonsteel is a conventional denomination for steel that has almost no other metallicelements added into it.ASTM most employed carbon steel for pipes are ASTM A53 Grade A and B and ASTMA106 Grade A and B. A53 used to be cheaper than A106 and Grade A cheaper thanGrade B. Today the difference is not so big, so that for small quantities ASTM A106Gr. B is usually chosen. ASTM Specifications belonging to same family of CarbonSteelSEAMLESS PIPES ASTM A53 (Gr. A / B) or A106 (Gr. A / B) WELDED PIPES ASTM A134 / A135 / A139

WROUGHT FITTINGS ASTM A234 (WPA / WPB)FORGED FITTINGS A105CAST PARTS A216 (WCB)

API Standards

For Oil and Gas Industry, another American Standardization Institute is commonand important. This Institute is


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API = AMERICAN PETROLEUM INSTITUTERules, Practices and Standards for Oil and Gas Industry are issued by this Instituteand followed by almost all Oil and Gas Companies in the world. Among the manyStandards issued by the Institute there is also a Standard for design of Pipelines:API STANDARD 5L Within this Standard Materials for Oil and Gas transportationpipelines are specified, with denomination API 5L This is a family of Carbon Steelsalmost equivalent to ASTM A53 /A106.

LOW ALLOY STEEL

The introduction of other elements into steel can change very much its mechanicalcharacteristics. Steel is subject to a process called creep at high temperatures(T > 540 C) Creep is a reduction of strength over time due to high temperature. It

means that if today the steel can withstand a certain pressure, after a long time at hightemperature same steel can withstand much lower pressures, since its resistance is decreasingwith time due to the high temperature. Steel becomes also particurarly fragile if submitted tosudden impacts at low temperatures (< - 20 C).

The introduction of small percentages of chromium (Cr), nichel (Ni), magnesium(Mg), manganese (Mn), molybdenum (Mo), proves to improve the strength of thesteel and its resistance to corrosion also at high temperatures (> 500 C) or at lowtemperaturea (< -20 C). Low Alloy Steel is a conventional denomination for steelswhere there are small percentages of elements, usually metallic, other than carbononly. Alloy steels are usually identified with denominations that recall composition.As for example following high temperature resistant steels: Denomination Alloypercentage Grade Grade for Castings5Cr- Mo (5% Cr0.5% Mo ) P5 C51 Cr- Mo- Si (1.25% Cr0.5% MoSi) P11 (WC5)1Cr- Mo (1% Cr0.5 Mo) P12 (WC5)

2 Cr- 1Mo (2.25 Cr1% Mo) P22 WC9ASTM Specifications belonging to same families of Low Alloy SteelsSEAMLESS PIPE A335 (P5P11P12P22)WELDED PIPE ASTM A358WROUGHT FITTINGS ASTM A234 (WP5WP11WP12WP22)FORGED FITTINGS A182 (F5F11F12F 22)CAST PARTS A217 (C5WC5WC9)

STAINLESS STEEL

One of most important problems with carbon and low alloy steels, is that the ironexposed to air and water combines with oxygene (O 2 ) and generates rust (di- iron

tri- oxyde Fe 2 O 3 ) that peels out from the surface. High percentages of chromium(Cr) and nichel (Ni) added into the steel stop this problem. Stainless Steel isconventional generic denomination for steels with high percentages of chromium(minimum 16%) and nichel (minimum 8 %). Traditional denomination for stainlesssteel was given first from AISI (American Institute for Steel and Iron) and is still inthe tradition and retained in the Grade of ASTM Specifications. But as usual for alloysteels, a more precise denomination can refer to composition. AISI DenominationAlloy Percentage Grade for


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Castings304 / 304L 18Cr- 8Ni (18% Cr8% Ni) CF3 / CF8316 / 316L 16Cr- 12Ni- 2Mo (16% Cr12% Ni2% Mo) CF3M / CF8M321 18Cr- 10Ni- Ti (18% Cr10% NiTi) Not AvailableThe L suffix stands for Low Carbon. In fact the presence of high percentages of Cr and Niimproves the resistance of steel against rust, but at one cost: stainless steel is very difficult toweld. Welding of stainless steel can be improved by reducing the content of carbon in it. ASTMSpecifications belonging to same family of Stainless SteelSEAMLESS PIPE A312 TP304304L - 316 - 316L - 321WELDED PIPE ASTM A249 TP304 - 304L - 316 - 316L - 321WROUGHT FITTINGS ASTM A403 WP304 - 304L - 316 - 316L - 321FORGED FITTINGS A182 F304304L - 316 - 316L - 321CAST PARTS A351 (CF3CF3M / CF8CF8M)

How Pipeline CHARACTERISTICS are defined by the Standards.

SIZE

NOMINAL PIPE SIZE : NPS It is a conventional size expressed solely in INCHES,related to the cross section diameter of the pipeline. For smaller sizes the NPS is notusually exactly equal to any real diameter, but bigger. This comes from the fact that foruniformity, pipelines must have same Outside Diameter, and change Inside Diameter withdifferent thickness. But in fluid transportation the internal diameter is more significant, so if theOutside Diameter is bigger of the NPS, taking away the thickness, the NPS gives more an ideaof the internal diameter. NOMINAL DIAMETER : DN Same as NPS, but in mm. It is the usualdenomination of Size in Europe where S. I. is adopted. All external diameters pipes accordingEUROPEAN Standards (DIN - Germany, UNI - Italy, AFNORFrance) areexactly equal of the equivalent NPS Sizes according AMERICAN andBRITISH Standars (BS) EXCEPT 5 (DN125)

WALL THICKNESS (1)1. For PIPES and WROUGHT BW FITTINGS, wall thickness isgiven in INCHES or mm.Some series of thicknesses are standardized. There are two series of systems ofstandardized thicknesses. Carbon SteelANSI B16.105, 10, 20, 30, 40, 60, 80,100, 120, 160. ScheduleStainless SteelANSI B16.195S, 10S, 20S, 30S, 40S,60S, 80S.

Std Standard

XS Extra Strong Weight SeriesXXS Extra Extra StrongIt happens that for a given diameter the thickess of one Schedule is equal to thethickness of one Weight Series. For example for small diameters, Sch. 40 is equal to


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Std Weight. THIS IS NOT A RULE, and this idea is one of the most common mistakesin piping design.

WALL THICKNESS (2)2. For FLANGES, VALVES and FORGED FITTINGS, a differentsystem of indicating the wall thickness is used. This is called PRESSURE RATING. Itis a NUMBER expressed in POUNDS per SQUARE INCH (PSI symbol #) that refers tothe maximum internal pressure acceptable for normal operation inside that part.125# 150# 300# 400# 600# 800# Cast Iron Flanges & Valves (Not in NPStandards) Fl. & Valves Forged Small Valves ( 2) 900# 1500# 2500# 3000# 6000#9000# F l a n g e s & V a l v e s Forged Fittings This conventional number is notexactly the actual maximum pressure acceptable inside the part. The maximumpressure allowed for a given rating is tabulated in the ANSI standards and dependson Temperature ASTM Material

TYPE OF JOINTS BETWEEN PIECES (1)

BUTT- WELDING ENDS The end is machined to allow head to head full penetrating

welding

TYPE OF JOINTS BETWEEN PIECES (2)

SOCKET WELDING ENDS A socket is provided where pipe can be inserted

TYPE OF JOINTS BETWEEN PIECES (3)3. THREADED ENDS Parts to be connected are threaded. For services where leaksarestrongly undesired, a light weld is carried out at the surface, this is called SealWeld. Seal weld

STANDARDIZED PIPING OBJECTS PIPES

FITTINGSFLANGESVALVESGASKETSBOLTS AND NUTS

PIPES: ANSI B36.10 CS / B36.19 SSSeamlessElectric Resistance Welded No material is added during welding

processElectric Fusion Welded Material (Filler Metal) is added during theprocess of welding

HOW TO IDENTIFY A PIPE SIZE NPS 12 (DIAMETER) (DN 300)WALL THICKNESS Sch. 40 MATERIAL ASTM A106 Gr. BBW FITTINGS : ANSI B16.9Bends 30 - 45 - 60 - 90


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Long Radius R= 1.5 DShort Radius R= DTeesStraight Full Tees .Reducing Tees.ReducersConcentric Reducers.Eccentric Reducers.CapsHOW TO IDENTIFY A BW FITTING1. Straight Fittings TYPE BEND 90 LR SIZE NPS 12 (DIAMETER) (DN 300)WALL THICKNESS Std MATERIAL ASTM A234 WPB

2. Reducing Fittings

TYPE REDUCING TEE SIZE NPS 12 x8 (DIAMETER) (DN 300x200)WALL THICKNESS Sch. 30x20 MATERIAL ASTM A234 WPB FORGED FITTINGS ANSI

B16.11

HOW TO IDENTIFY A FORGED FITTINGTYPE ELBOW 90 SIZE NPS 1 (DIAMETER) (DN 25) WALL THICKNESS Rating 3000#JOINT NPT MATERIAL ASTM A105

PIPE NIPPLES

They are standardized short pieces of pipe usually 50 mm or 100 mm long normallyused between two close fittings. They can come in straight size or in reducing sizeand can have one end machined in a different way than the other. Such a variety of

combinations is summarized using abbreviationsB = BevelledP = PlainT = ThreadedL = LargeS = Small E = End

Pipe nipples can be used to change among joint types. For example a PExBE Pipe Nipple changes a Socket Welding Line into a ButtweldingLine Beveled End Plain End BW SW FLANGES ANSI B16.5

1. 1. Pipe ConnectionWelding NeckSlip OnLap JointSocket Welding

Threaded2. Mating


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Flat FaceRaised FaceRing Joint

WELDING NECK

Used for all sizes, they allow full penetration weld between pipe and flange. For thisreason they are used for severe applications where failure of weld cannot beaccepted. This does not come free of cost, since the shape of the flange obliges tostart from a heavy forging and waste a lot of material from machining.

SLIP ON

Used for all sizes, they are very much economical because they are flat and can beobtained from sheets or plates with minimum waste of material from machining.But they do not allow full penetration weld, so that they are use for low ratings(usually 150# only) and uncovered applications

THREADED

Can be used for all sized, but are preferably used for small sizes (< or equal to 2).Cheap manufacturing, cheap installation (no weld is required) but limited tothreadellines, that means unsevere applications where leaks are not a major issue

LAP JOINT

A Stub End is welded on the pipe after the flange insertion of it. This solution is used

for Stainless Steel lines at low pressure, since the heavy flange does not come incontact with the conveyed fluid and can be provided in much cheaper Carbon Steelmaterial. Moreover no weld is required, also a good thing for Stainless Steel lines.

SOCKET WELDING

Used for small sizes (< or equal to 2) for unsavory services on Socket Weldinglines.Flat Face Gasket: Full Face Flat It covers the entire surface of the flange Raised FaceGasket: Flat It covers the raised surface of the flange Spiral Wound Also known asSpirometallic, or Spirotallic, its a wounded spiral of Stainless Steel and Graphite towithstand high temperatures or severely aggressive fluids Ring Joint Gasket:

Metallic Ring It is normally made up of Steel. It deforms inside the ring jointgroovesassuring sealing at very high pressures. Surface Finishing of Flanges To improve thesealing effect of plane gaskets, the surface of a flange can be machined. A set ofcircular scares is machined in the surface. When the gasket is tightly squeezedetween the flanges, it penetrates into the scares improving sealing.

HOW TO IDENTIFY A FLANGE


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JOINT TYPE -SLIP ONSIZE -NPS 6(DIAMETER) -(DN 150)WALL THICKNESS -Rating 300#MATING_FINISH - RFR9MATERIAL- ASTM A105

ACTUATION OF VALVES

To open and close a valve, Hands, Electric Power, Compressed Air, High Pressure Oilyou can use in which case you need Hand wheel, Electric Actuator, Pneumaticactuator, Hydraulic Actuator And is called Manual, Electric, Pneumatic, Hydraulic

CONTROL VALVES

These valves are used to CONTROL one or more of the PROPERTIES of the conveyedfluid in order to mention the VALUES of the controlled property within a specific

ange.The internal parts of these valves are specially designed tu suit the particular control task andare non subject to particular Standards. Anyway, the majority of Control Valve Manufacturerstry to respect at least the end to end dimensions given in ANSIB16.25. Also connections followsthe recognized international standards.

SAFETY AND RELIEF VALVES

These valves are installed on pipelines where pressure can exceed by accident the DESIGNPRESSURE of the pipeline. These valves are designed to open and discharge the conveyed fluidwhen the pressure in the pipeline becomes greater than a pecified value called SET. RELIEF

The valve opens when the pressure goes over the SET, but close again when the pressurereturns under the SET SAFETY The valve opens when the pressure goes over the SET, butnever closes again. Personnel intervention is required on the pipeline to check the event andthe condition of the area, before re- arming the valve and starting operation again

TUBING

A TUBE is a circular section of given DIAMETER and THICKNESS. It is normallyspecified giving the Ouside Diameter (OD) and the thickness. But it can also bespecified giving the Inside Diameter (ID) and the thickness. The given numberscorrespond exactly to the geometrical dimension they refer. So A 2 OD TUBE hasexactly a 2 Outside Diameters. Dimensionally, there are two big families of tubing

1. 1. FRACTIONAL TUBES

The INCH is the unit of measure, and since tubes for piping purpose (REMEMBER:

CONVEYING FLUIDS!) are small, usually less than 1, FRACTIONS of inch are used,hence the name


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FRACTIONALMETRIC TUBES

As per SI requirements, mm is the unit of measure. Again the value in mm is the actual ousidediameter of the tube, so that a DN15 pipe has a rather different OD then a 15 mm tube.

TUBES in PIPING DESIGN.Tubes are not usually used in PIPING DESIGN except for some very particularservices. In typical Oil and Gas Machinery installations, like Nuovo Pignones, TUBES are basically used for: 1. Parts of HP Hydraulic Lines 2. Instrumentconnecting Lines

Pneumatic Lines

These Lines are small size (usually less than 1).COMPRESSION FITTINGSTubing is usually BENT.

A large variety of fittings are available for1. detachment of BRANCHES (Tees)2. Passing through steel walls (Bulk Unions)3. Unite tube to tube (tubing is not welded)4. Connecting Tubing to PIPES (Connectors)5. Connecting Tubes to Flexible HosesConnection of TUBING with the fitting isachieved through a particular locking system where a RING ( FERRULE) is forcedto COMPRESS the Tube walls for sealing and joining. These fittings are notSTANDARDIZED, but are branding based and patented. Most popular manufacturersof compression fittings are PARKER, SWAGELOCK, GARILOCK.

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