Manuel Gare Itag

BA-Pig-CE-en-04-39

Pig Valve Type PC / PB / PS

Installation and Operation Manual

ITAG PIG VALVE TYPE PC / PB / PS 3

General Safety References • Please read this manual carefully before using the valve. This manual contains important

information concerning safety, installation, operating and maintenance.

• Keep this manual carefully and ensure that it is available for installation, operating and maintenance personnel.

• The valve may be used only for the intended purpose in accordance with this manual.

• Operation of this valve is subject to the regulations of this manual, the operating company and, possibly, national regulations of the respective user country.

• Installation and maintenance of this valve may be executed only by sufficiently qualified and authorised technical personnel.

Safety Symbols • In this manual the following safety symbols may be used, in order to refer the reader to

important text passages:

This symbol means a directly imminent danger for the life and the health of persons.

Ignoring has heavy injurious consequences for person‘s health, up to person‘s life.

This symbol means a possibly imminent danger for the life and the health of persons.

Ignoring can entail heavy injurious consequences for person‘s health, up to person’s life.

This symbol means a possibly dangerous situation.

Ignoring can entail slight injuries or damages.

This symbol gives important notes for adequate handling of the equipment.

Ignoring can lead to disturbances at the equipment or in the environment.

This symbol refers to particularly useful information and user tips.

Further Important Notes • Only original spare parts may be used in accordance with the respective parts lists.

• For the consequences of inappropriate installation, commissioning and maintenance as well as operating outside of the specification, ITAG takes neither liability nor warranty.

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4 ITAG PIG VALVE TYPE PC / PB / PS

Table of Contents

GENERAL SAFETY REFERENCES ....................................................................... 3

SAFETY SYMBOLS................................................................................................. 3

FURTHER IMPORTANT NOTES............................................................................. 3

TABLE OF CONTENTS........................................................................................... 4

1 DESCRIPTION .................................................................................................... 5 1.1 The ITAG Pig Valve System ........................................................................ 5 1.2 The ITAG Pig Valves ................................................................................... 6 1.3 Intended Use, Restrictions of Use ............................................................... 7 1.4 Versions of ITAG Pig Valves ....................................................................... 7 1.5 Pig Trap Closure Types ............................................................................... 9 1.6 Drain Device .............................................................................................. 11 1.7 Pig Ejection Device (optional).................................................................... 11 1.8 Flushing Device (optional) ......................................................................... 12 1.9 Pigs ............................................................................................................ 13

2 TRANSPORT AND STORAGE......................................................................... 15 2.1 Transport.................................................................................................... 15 2.2 Storage ...................................................................................................... 15

3 INSTALLATION AND COMMISSIONING ........................................................ 16 3.1 Installation Position and Flow Direction..................................................... 16 3.2 Inspection before Installation into the Pipeline .......................................... 18 3.3 Demands imposed to the Pipeline ............................................................. 18 3.4 Installation into the Pipeline ....................................................................... 18 3.5 Commissioning .......................................................................................... 19 3.6 Pressure Test............................................................................................. 19 3.7 Removing from the Pipeline (Flanged Connection)................................... 20

4 OPERATION ..................................................................................................... 21 4.1 Pipeline Design for Pigging........................................................................ 21 4.2 General References for Valve Operation................................................... 23 4.3 Closing and Opening Operations............................................................... 23 4.4 Pig Launching ............................................................................................ 25 4.5 Pig Receiving ............................................................................................. 26 4.6 Permissible Pig Velocity ............................................................................ 27 4.7 Slow-Down of Pig Velocity......................................................................... 28 4.8 Operations with Trouble and Defects ........................................................ 29

5 MAINTENANCE ................................................................................................ 30 5.1 Storage ...................................................................................................... 30 5.2 Preservation............................................................................................... 30

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1 Description 1.1 The ITAG Pig Valve System

In general, pigs (also called „scrapers“) are used for purposes of cleaning, draining, inspection and calibration of pipelines, as well as for the separation of different media.

For launching and receiving of pigs two different principles are usual (fig. 1.1):

Pipeline System with Pig Traps

Pipeline System with Pig Valves

Fig. 1.1 Principles of Pig Launching and Receiving Systems

Using pig valves requires only two special valves (“pig valves”) for launching and receiving. This system is illustrated in fig. 1.2:

Fig. 1.2 The ITAG Pig Valve System (principle)

It consists of the two pig valves, which are directly installed into the pipeline. The installation of special launchers and receivers or by-passes, is not necessary. Moreover, only one shut-off valve is required at each station, that is the pig valve itself. This simple system for the launching and receiving of pigs saves space as well as costs.

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1.2 The ITAG Pig Valves The design of the ITAG pig valves type PC, PB and PS is based on the ITAG shut-off ball valve type IT. For the purpose of launching and receiving of pigs the valve is equipped with some special features like pig trap, pig trap closure and a special valve bore with stopper bars (fig. 1.3).

Stopper Bars Ball Pig

Pig Trap Pig Trap Closure

Fig. 1.3 The ITAG Pig Valve (principle design)

Pig Launching and Receiving

The principle of pig launching is quite simple: After turning the ball to the closed position, the pig trap is isolated from the pipeline pressure and the pig trap closure can be opened. The pig is inserted into the ball bore, and after closing the pig trap the ball is returned to the open position. Now the pig is driven forward in the pipeline by the flow of the medium.

The pig receiving procedure is similar: The flowing medium has driven the pig towards the pig receiving valve, where it is stopped in the valve bore by the stopper bars. Now the ball is turned to the closed position, the pig trap closure can be opened, and the pig can be removed.

Valve Design

The design of the ITAG pig valves is based on the ITAG shut-off ball valve type IT. Due to the top entry design the valve’s interior parts can be easily installed and disassembled, without the need to remove the valve from the pipeline.

For that purpose the ITAG pig valves are equipped with a seat ring system that makes it possible to assemble and disassemble the ball without axial shift of the seat rings and with-out the need of special tools.

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The ITAG pig valves type PC, PB and PS have the following design features:

Body 1-piece type, top entry design

Ball Trunnion mounted

Stem Anti blow-out

Seat ring type Single piston effect / self relieving

Double-block-and-bleed Yes

Tab. 1.1 Design Features

1.3 Intended Use, Restrictions of Use The ITAG pig valves type PC, PB and PS are pig valves for industrial applications.

The allowable operating range (allowable pressures, temperatures and flow media) and explicit application exclusions result from the name plate on the valve, from this manual and, in case, from respective contract documents.

If the valve is provided with an actuator, references and limits in the user information of the actuator have to be regarded, too!

The operator of the plant is responsible that the valve is only used within the allowable operating range.

1.4 Versions of ITAG Pig Valves

ITAG pig valves are available in three different versions for different purposes. They differ in the design of the valve ball and are designated as PC, PB and PS:

Type PC (“Cleaning”) The standard version is the PC pig valve. In this version, the valve ball has a bore whose cross-section is about 25 percent larger than that of the pipeline.

Therefore the flow of the medium is partially maintained, when the pig has arrived in the receiving valve. Impurities which are carried along by the pig, can thus be flushed further on to a following dirt separator.

In closed position the ball of the valve totally shuts-off the pipeline.

Fig. 1.4 Pig Valve Type PC

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Type PB (“By-pass”) In the PB version, the valve ball has a bore whose cross-section is about 25 percent larger than that of the pipeline (the valve bore is identical with that of the PC type).

But unlike the PC version, the ball of the PB valve has one or more by-pass channels, so that in fully closed position of the ball the medium flows through the by-pass channels in pipeline direction. This feature maintains a (reduced) flow of the medium also in the fully closed position of the valve.

Fig. 1.5a Pig Valve Type PB (open position)

Fig. 1.5b Pig Valve Type PB (closed position)

Type PS (“Separation”) The PS version of the ITAG pig valve is specially designed for the purpose of keeping different media separate.

The valve ball of the PS version has a bore whose diameter exceeds that of the pipeline by approximately 5 percent and a sealing ring is situated in the ball bore.

Both features ensure that the media in front of the pig is kept separate from the media behind the pig when the pig arrives in the valve bore.

In closed position the ball of the valve shuts-off the pipeline totally.

Fig. 1.6 Pig Valve Type PS

Bypass Channels

Bypass Channels

Sealing Ring

The standard PS valve is designed for the exclusive use of spherical separation pigs. If cylindrical separation pigs shall be used, a special version of the PS type is required.

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1.5 Pig Trap Closure Types Depending on the valve size ITAG pig valves are equipped with three different versions of pig trap closures:

Valve Size:

from 2’’ to 8’’ Class 900

Cover with hand lever, bayonet lock with safety locking device

Fig. 1.7

Valve Size:

from 8’’ Class 1500 to 14’’ Class 600

Hinged door with hand lever, bayonet lock with safety locking device

Fig. 1.8

Valve Size:

16’’ and larger

Hinged door with handwheel, bayonet lock with safety locking device

Safety Locking Device

Cover Hand Lever

Safety Locking Device Door Suspension

Door Hand Lever


Door Handwheel

Fig. 1.9

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The Safety Locking Device prevents the operator from opening the pig trap closure while there is still an overpressure inside the pig trap.

The Safety Locking Device consists of a locking pin, combined with a pressure warning valve (fig. 1.10):

Lever

Pig Trap Pressure Warning Valve

Locking Pin Pig Trap Closure

Fig. 1.10 Safety Locking Device

The locking pin leads through a bore in the valve body to a bore in the pig trap closure. The locking pin only can snap into the counter bore in the trap closure, if the closure is in the fully closed position.

On the other hand the locking pin is linked to the lever of the pressure warning valve. Only if the locking pin is snapped in the counter bore of the trap closure, the pressure warning valve is closed.

If the locking pin is snapped in the counter bore of the trap closure, it blocks the trap closure. To open the trap closure the locking pin must be pulled out which automatically opens the pressure warning valve.

The function of the "pressure warning valve" is to let the operating personnel know, whether the pig trap is de-pressurized for sure, by hearing the sound of escaping media in the case if the pig trap is still not de-pressurized.

The pressure warning valve must not be installed to a contained piping system, as it would constrain the warning function. To install an open pipe is allowed as long as it is assured, that the operation personnel is able to hear escaping media.

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1.6 Drain Device The ITAG pig valves are equipped with a drain device, located on the bottom of the pig trap:

Fig. 1.11 Drain Device

The drain device is used to drain, de-pressurize and vent the pig trap before the trap closure is opened.

If the drain valve will be connected to a piping system (recommended in the case of potentially harmful media), then a pressure gage must be installed into the piping near by the drain valve to control the pressure during discharging

1.7 Pig Ejection Device (optional) For easier ejection of the pig the valve may be equipped with a pig ejection device (optional). This device consists of an ejection valve on the backside of the pig valve and an ejection rod:

Fig. 1.12 Pig Ejection Device

Pig

Drain Device

Ejection Valve Ejection Rod

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To eject the pig the valve must be in fully closed position and the pig trap closure opened. Then the ejection valve is opened und the ejection rod is inserted through the ejection valve as shown in fig. 1.12.

The ejection valve can also be used as flushing valve.

1.8 Flushing Device (optional) For media which may be harmful for health and environment, the pig valve may be equipped with a flushing device to flush valve cavity, valve ball bore and pig trap before the pig trap closure is opened (fig. 1.13).

Flushing Valve

Drain Valve

Fig. 1.13 Flushing Device

For flushing the valve ball must be in the fully closed position (fig. 1.13). A carrier gas is passed in through the flushing valve, flows through the pig valve and escapes through the opened drain valve.

After completion of the flushing procedure, the flushing valve can be closed and the pig trap closure can be opened.

Escaping medium may be harmful for health and environment. Possibly the drain valve should be connected to a flare system.

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1.9 Pigs Table 1.2 gives a survey of various types of pigs. Which kind of pig is suitable, depends on the type of the respective pig valve. For concrete recommendations, please contact ITAG.

Description

Cle

anin

g

Filli

ng

Empt

ying

Dry

ing

Sepa

ratin

g

Cal

ibra

ting

Spherical Pig Inflatable sphere, made of poly-urethane or perbunan (synthetic rubber, PUR or NBR)

Multicup Pig Steel body with cups (PUR or NBR)

Plastic Foam Pig Cylindrical body, made of plastic foam (PUR or PE foam)

Ring Scraper Pig Cylindrical body (POM) with frontal scraper ring (PUR or NBR) and cups (PUR or NBR)

Brush Pig Steel body with brushes (steel or plastic) and cups (PUR)

Scraper Pig Steel body with cups (PUR), scrapers (hardened steel) exchangeable with steel brushes, on spring arms

Plastic Foam Pig with brush straps Cylindrical body, made of plastic foam (PUR foam), with helical cleaning rings (PUR, corundum)

Gauging Pig Steel body, with frontal gauging plate (hardened steel) and cups (PUR)

Tab. 1.2 General information about pigs

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For use in ITAG pig valves, the overall length of the pig must not be larger than 1.4 times of the respective bore diameter according to API Standard 6D / ISO 14313:1999.

Characteristics and application

The spherical pig is filled with water and then inflated to a diameter which is 2 to 3 percent larger than that of the pipeline. Therefore, within certain limits, it can be adapted to different inner diameters of pipelines. This type of pig is applicable for pipe bends whose radius is at least 1.3 times the pipe diameter. Moreover, spherical pigs can pass through almost any elbows and fittings.

This type of pig is very versatile. Since the cup diameter is about 3 percent larger than that of the pipeline, complete contact between the pig and the pipe wall is ensured. Thus, this pigs are suitable for medium separation, emptying and drying.

Foam pigs are used with an outer diameter which is 6 percent larger than that of the pipeline. Due to the flexibility of the pig, constrictions in the pipeline, caused by throttles, elbows or other equipment and fittings, can be passed without difficulties. Due to abrasion, foam pigs whose surface is not reinforced, have only a limited service life. Also they are not applicable with high operating pressures.

Because of its hardness, the front scraper ring ensures thorough cleaning even with thick deposits. The main function of the cups is to prevent flow of the medium around the pig and to remove residual deposits.

This pig is designed for applications where hard deposits shall be removed. The diameter of the brushes is about 2 percent larger than that of the pipeline. Pigs with steel brushes should not be used for pipelines with interior paint or plastic coating. In this case pigs with plastic brushes are recommended.

This pig is recommended for removing hard deposits, corrosion and incrustations. It should not be used for pipelines with interior paint or plastic coating.

Due to the cleaning rings this pig offers better cleaning and less abrasion compared with simple plastic foam pigs.

The gauging pig is especially used for inspecting new pipelines for a smooth and round cross section. Weld beads and residues such as welding electrodes and tools, are removed from the pipeline. The diameter of the gauging face plate is 90 to 95 percent of the inner diameter of the pipe.

Tab. 1.2 General information about pigs

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2 Transport and Storage 2.1 Transport

For transport the ball of the valve must be in full open position. The ends are closed with protective caps in order to protect the valve from internal damages and impurities. The caps should not be removed before installing the valve into the pipeline.

The valve is possibly equipped with extending components. Caution when removing the transportation packing!

On the transport to the installing location the following safety references have to be regarded:

- Use only certified and suitable lifting devices in consideration of the total weight of the load.

- Fasten the lifting devices in a way that they cannot slide off. If the valve is equipped with lifting lugs, use them for fastening the lifting devices.

- Never fasten the lifting devices to the actuator but always to the valve body.

- Use suitable supports for the lifting devices in order not to damage the exterior surface protection of the valve.

- Pay attention that the lifting devices do not collide with extending components of the actuator.

- Protect the load against lateral tilting.

- Do not stay underneath hanging loads.

2.2 Storage The ball valve should be stored in dry, sheltered and ventilated areas. The ball of the valve should be in full open position, the ends should be closed by protective caps.

New un-used valves can be stored normally without additional actions. For longer storage however additional preservation actions are recommended.

For a longer storage of used valves, corrosion protection is recommended by thorough cleaning and careful preservation of all parts, particularly after operating in aggressive media (see para. 5.2).

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3 Installation and Commissioning

3.1 Installation Position and Flow Direction a) Installation Position

Standard Installation Position:

The standard installation position of ITAG pig valves is pipeline axis and axis of the pig trap truly horizontal (fig. 3.1):

Fig. 3.1 Standard Installation Position of ITAG Pig Valves

Deviations from the horizontal position are permissible only according to table 3.1:

Pig Trap Closure Type *) Permissible Deviation from Horizontal Position

Cover with Hand Lever ± 10° Hinged Door

with Hand Lever or Handwheel ± 3°

*) see para. 1.5

Tab. 3.1 Permissible Deviations from Horizontal Position

Installation positions outside the permissible limits may cause problems with opening the trap closure and receiving and removing the pig.

Special Installation Positions:

On request special versions of the ITAG pig valves are available for installation positions other than horizontal, e. g. vertical pipeline or horizontal pipeline with pig trap upwards.

Please refer to special instructions for these cases.

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b) Flow Direction

The flow direction results from the purpose of the valve (“launcher” or “receiver” valve) and the direction to close the valve (“clockwise to close” or “counter-clockwise to close”).

On top of the valve an indicator shows the position of the ball and the position of the stopper bars:

Stopper Bars Mark

Indicator

Fig. 3.2 Position Indicator

Together with the indicator on the valve and the schematics in table 3.2, the flow direction can be determined:

Flow Direction Clockwise to Close (Stopper bars “left”)

Counter-Clockwise to Close (Stopper bars “right”)

Launcher „Right“ Receiver „Left“

Receiver „Right“ Launcher „Left“

Tab. 3.2

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3.2 Inspection before Installation into the Pipeline The following points should be checked before installation:

• Compatibility of the valve with the required purpose (launcher or receiver) and flow direction (→ para. 3.1 b)

• Compatibility of the valve ends with the pipe connections

• Swivelling range of the ball: The angle between the two end positions „open“ and „closed“ must be 90°.

• Position of the ball: During installation the ball must be in full open position, in particular when welding, in order to avoid damages of the sealing surfaces.

3.3 Demands imposed to the Pipeline The pipeline should be assembled without stress as far as possible, in order to avoid stressing the valve by outside loads in the form of pipeline forces and moments. Possibly a suitable fixing or a flexible support of the pipeline should be planned.

The valve never must be used as exclusive fixed point. The pipeline always should be supported additionally.

3.4 Installation into the Pipeline ITAG pig valves must be installed by competent personnel according to the technical regulations of pipeline construction.

a) General:

• The valve has to be installed in full open position and may not be operated in the meantime, so that no impurities can be pressed into the seats and thus damage the seat rings.

b) Valves with flange connections:

• Adjust valve and pipeline axis.

• Use only new un-used seals.

• Pay attention to the recommended torque for the flange bolts.

c) Valves with buttweld connections:

• Adjust valve and pipeline axis.

• During welding as well as during the possibly necessary post weld heat treatment, it must be paid attention, that the temperature in the body in a distance indicated in the table 3.3, does not exceed 120 °C:

Nominal Size Distance from welding seam DN 25 – 80 (1“ – 3“) 50 mm

DN 100 – 200 (4“ – 8“) 80 mm DN 250 – 400 (10“ – 16“) 100 mm

> DN 400 (16“) 150 mm

Tab. 3.3

During welding and heat treatment, the seals of the seat rings are in danger to be damaged by overheating of the body. If necessary this area must be cooled professionally.

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3.5 Commissioning Before putting the valve into operation the piping has to be cleaned and rinsed carefully with adequate measures. It must be guaranteed that the ball of the valve remains thereby in full open position and is not operated during the cleaning phase.

Operating the valve before or during the pipeline cleaning procedure can press impurities into the seats and damage the seat rings. Such damages are not subject to ITAG‘s warranty.

ITAG does not accept responsibility for possibly negative consequences of pipeline pickling procedures.

a) Actuator (if scope of supply):

Actuators on ball valves are put into operation according to the manuals of the respective manufacturers. Electrical components must be connected by electrical specialists.

Electric actuators with 3-phase power supply have to be checked for correct phase connection before first operating. In the case of doubt the ball of the valve should be driven by hand into a 45°-position and then checked the direction of turning. Afterwards the ball should be driven back into the end position.

3.6 Pressure Test a) Test Fluid It may be used only test fluids that can not cause corrosion at the inner parts of the valve.

If necessary suitable corrosion protection measures must be taken, e. g. addition of corrosion protection inhibitors to the test fluid.

b) Test Pressure The maximum allowable test pressure normally is 1.5 times the maximum allowable pressure (see chapter 1.4) . Pressure tests with higher pressures are permissible only with a written approval of ITAG.

c) Auxiliary Valves and Openings Auxiliary valves and openings, e. g. pig trap closure, drain valve and pressure warning valve, must be closed before starting the shell test.

If the test pressure is higher than the maximum allowable pressure differential of the auxiliary valves (normally 1.1 times the maximum allowable pressure of the auxiliary valve), then these valves must not be closed by their closure members but by blind plugs or blind flanges (closure member must stay in full open position).

Inadmissible pressure differentials may damage the sealings of the closure members.

d) Pressure Test The maximum allowable pressure differential of the valve is 1.1 times the maximum allowable pressure. Exceeding this value may damage the seat rings

With test pressures higher than 1.1 times maximum allowable pressure, the ball of the valve must be in half-open position, to avoid an unallowable pressure differential.

Immediately after completion the pressure test, the ball of the valve must be driven back into one of the end positions (full open or full close) and must not left in half-open position. The cavity shall be drained by opening the drain device.

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e) Special Case ‘Long-term Pressure Test’:

With pressure tests, lasting longer than approx. 6 hours, please apply in deviating from the normal pressure test:

The ball of the valve should not be located in half-open position. Otherwise the seat ring seals may get irreversible pressure marks by the long testing period.

However it must be ensured that no inadmissible differential pressure arises (see above). That can be guaranteed if in the body cavity the same pressure exists as in the pipeline. To achieve this, the ball of the valve remains in the half-open position before the full test pressure is reached. Only now the ball is switched into full-open position. The body cavity must not be relieved during the testing period then.

Before relieving the pressure in the pipeline at the end of the pressure test, the ball must be driven back to half open position to release the pressure in the body cavity simultaneously.

Immediately after completion the pressure test, the ball of the valve is driven again into one of the end positions and is not left in half-open position.

3.7 Removing from the Pipeline (Flanged Connection) Before removing the valve, the pipeline must be pressureless and drained.

• The drain valve is opened and the valve ball is driven into a 45°-position to completely drain the valve.

• The valve ball is driven back into full open position.

• The flange bolts between valve and pipeline are released. It must be paid attention to possibly existing locked-up stress.

• The valve is removed from the pipeline carefully, so that connection ends (in particular sealing strip and/or sealing groove) are not damaged.

• After removing, the valve body should be drained and cleaned completely. For that purpose the valve ball is operated several times.

• The valve ball is driven into full-open position and the end connections should be protected by caps or plugs.

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4 Operation 4.1 Pipeline Design for Pigging

To make pigging operation possible, the pipeline system must meet certain conditions concerning pipe diameter, radius of pipe bends, pipeline branches, fittings, pipe connections, surface finish and provisions taken in the commissioning phase of the pipeline.

Pipeline Dimensions As a rule pig manufacturers have adapted their product assortment to meet ANSI and API specifications on pipe dimensions. Therefore the basic diameter for a pig size is usually adapted to the “standard (Std)” or “schedule 40 (Sch 40)” wall thickness.

Pigs can also be used in pipelines whose inner diameter deviates from these standard dimensions, if the cup or brush diameter is adapted accordingly. However, pigs of this kind are special-made versions.

The installation of pipe fittings such as elbows, tees or shut-off valves may cause deviations of the internal diameter. A maximum deviation of 2 percent from that of the pipeline is permissible. Transitions should be smooth.

Pipe Bends For optimum pigging the radius of pipe bends should be as large as possible. The permissible minimum radius of pipe bends depends on the kind of pigs (length, shape, rigidity). In general bends should have a minimum radius as follows:

3 D

1.4 D

ØDPipe Size D Minimum Radius

of Pipe Bends < 4’’ 10 D

4’’ – 12’’ 5 D > 12’’ 3 D

Tab. 4.1 Minimum Radii of Pipe Bends

However spherical pigs and special designed cylindrical pigs with a maximum length of 1.4 D can be used with minimum bend radii of 1.5 D.

Pipeline Branches Tee-fittings, elbows, and other sections of increased cross-sectional area must be bridged with appropriate guide bars or similar devices, in order to prevent the pig from getting stuck (fig. 4.1):

Guide Bars

Fig. 4.1 Pipe Branches

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Valves Only those valves which are suited for pig operation are acceptable (e. g. ball valves). Smooth transitions must be ensured. Openings or recesses within the valve must be bridged by guide bars.

Pipe Connections Welded joints, screw connections and flanges must be constructed without gaps, in which the pig might get stuck. Gaskets or weld seams which jut out into the pipe bore are not allowed.

321

Fig. 4.2 Sources of Trouble: Root Penetration (1), Misalignment (2), Varying Pipe Diameter (3)

Especially welded joints considerably affect the service life of a pig. With a carefully welded, smooth pipe, the service life of a pig is nearly unlimited. Hence, special attention must be paid to achieve a smooth internal surface of the weld seams during construction of the pipeline.

lf smoothness of welds cannot be ensured, each weld must be smoothed during the pipe-construction operation with the use of a gauging pig, mounted on a long rod. This gauging pig comprises a hardened steel disk whose diameter is smaller than that of the pipe by about 3 percent. Prior to the welding of the next pipe, the previous weld is to be trimmed by the gauging pig. If this cleaning procedure is not possible, for example in the case of guarantee or elbow welds, special caution is required.

Surface finish The interior surface of the pipe should be as smooth as possible, in order to ensure good results from pig operations as well as a long service life of the pigs. The smoothness of normal rolled pipes is sufficient. In the case of spirally or longitudinally welded pipes, attention must be paid to the smoothing of the welds. Pipes whose internal surface have been roughened by corrosion are not acceptable.

Commissioning of the pipeline Prior to first operation, the pipeline should be cleaned and freed of weld beads and other foreign bodies.

Using of cleaning pigs is recommended. For reasons of safety, they should be equipped with a bursting disc by-pass or a radio transmitter, to permit accurate localisation of the pig in the event of getting stuck.

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4.2 General References for Valve Operation The valve must be operated and supervised by competent and instructed personnel, so that employed and third persons are not endangered.

Appropriate operating instructions must be provided, so that the serving and maintenance personnel receive the necessary instructions for operating the valve.

The valve may be operated only within the permissible limits.

If the valve is equipped with an actuator, the references in the actuator manual must be regarded, too.

Appropriate national regulations of the user country for the operation of the valve may be considered if applicable.

4.3 Closing and Opening Operations a) Valve Ball Operation of the valve ball works alternatively: • Manually (by worm gears with handwheel) • Automatically (by motor drives)

The swivelling range of ITAG pig valves from full open to full closed position normally is 90°. The directions to close or open the valve, depends on the type of the valve (see para. 3.1 b)).

The end positions are limited by mechanical stops in the gears or in the actuator and are indicated by arrows and symbols. A detection of the position of the valve ball is given by a mechanical position indicator on top of the drive (see fig. 3.2).

With valves with allowable operating temperatures more than 50 °C, handwheels or levers may have surface temperatures, which can cause burns of the skin if they are touched without heat protection.

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b) Opening of the Pig Trap Closure Opening and closing procedures depend on the closure type of the valve (see para. 1.5):

• Cover with hand lever:

1. The ball of the pig valve must be in the fully closed position.

2. Open the drain valve to drain and de-pressurize the pig trap.

3. Open the safety locking device to de-lock the pig trap cover. The pressure warning valve of the safety locking device opens parallel and ensures, that the pig trap is de-pressurized for sure.

4. Turn the hand lever of the pig trap cover to the left (bayonet lock) and remove it.

• Hinged door with hand lever:



3. Open the safety locking device to de-lock the pig trap door. The pressure warning valve of the safety locking device opens parallel and ensures, that the pig trap is de-pressurized for sure.

4. Turn the hand lever of the pig trap door to the left to open it (bayonet lock). Pivot the door aside with the door suspension.

• Hinged door with handwheel:



3. Open the safety locking device to de-lock the pig trap door. The pressure warning valve of the safety locking device opens parallel and ensures, that the pig trap is de-pressurized for sure.

4. Turn the handwheel to the left to open the pig trap door (bayonet lock). Pivot the door aside with the door suspension.

Hand Lever Cover


Hand Lever

Drain Valve


Drain Valve Door


Drain Valve Door Handwheel

When opening the drain valve, note that the escaping medium is under pressure and may be harmful for health and environment. Possibly the drain valve should be connected to a flare system.

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c) Closing of the Pig Trap Closure The closing procedure of the pig trap closure is as follows:

1. Check that seals and sealing surfaces are clean and without damages.

2. Turn the cover or door of the closure so that its closure mark (fig. 4.3) is aligned with the “Open”-mark on the body.

3. Insert the cover or door and turn it to the right by the hand lever or handwheel until the closure mark exactly aligns with the “Closed”-mark on the body (fig. 4.3).

4. Close the safety locking device and the drain valve.

The safety locking device can not be closed before the closure is turned in its fully closed position.

Turning of the pig trap closure should be performable with relative ease. lf unusual forces should be necessary, the closure must be checked for foreign bodies or damages.

Any defects must be repaired before further use of the valve.

4.4 Pig Launching

For launching a pig, the following operations shall be performed in the indicated sequence1:

1 The ball of the pig valve must be turned to the fully closed position.

2 Open the drain valve to drain and de-pressurize the pig trap.

CAUTION: lf the medium is harmful to the environment, the drain valve should be connected to a flare system!

1 The launching sequence is shown with a 3‘‘-pic valve with cover closure. However the sequence is valid in general for all pig valves. Deviations are only caused by different closure types (see para. 4.3)).

Closure Mark

Closed

Open

Fig 4.3

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3 Open the safety locking device to de-lock the pig trap cover. The pressure warning valve of the safety locking device opens parallel and ensures, that the pig trap is de-pressurized for sure.

4 Turn the hand lever of the pig trap cover to the left to open and remove it (bayonet lock).

For opening other pig trap closures types: Please refer to para. 4.3 b).

5 Insert the pig into the pig trap, backside of the pig first, until it is stopped by the stopper bars.

6 Insert and lock the pig trap cover as described in para. 4.3 c) and close the safety locking device and the drain valve.

7 Now the valve is turned to the fully open position. The medium flow drives the pig through the pipeline.

When closing the pig trap closure, attention must be paid to the references in para. 4.3 c).

4.5 Pig Receiving The receiving procedure after the arrival of the pig in the receiving valve corresponds to step 1 to 4 of the launching procedure (see para. 4.4).

The pig is removed by pulling it out from the pig trap. For that purpose some pigs are equipped with a ring on the rear end.

lf scope of supply, the pig ejection device can be used for removing the pig (see para. 1.7).

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4.6 Permissible Pig Velocity When the pig arrives in the receiver valve, it is stopped by the stopper bars. The resulting impact causes stress in pig and stopper bars, which increases with rising velocities of the pig. lf the velocity is too high, either the pig or the stopper bars can be damaged. For this reason, the velocity of the pig must not exceed a permissible maximum.

The maximum permissible pig velocity depends on the physical condition of the flow medium (liquid or gaseous) and the valve size. Fig. 4.4 shows the limits:

Gaseous Media

Liquid Media

Nominal Valve Size in inch

Pig

Vel

ocity

in m

/s

Fig. 4.4 Permissible Pig Velocities

The pig velocity is approximately equal to the flow velocity of the medium in the pipeline.

For liquid media the flow velocity and thus the pig velocity can be calculated by:

idQv ×= 27.1 or 2

³

])[(][354][

mmdQvi

hm

sm ×=

v ... velocity Q ... volume flow di ... internal diameter of the pipe

For gaseous media the above mentioned formula does not work because of the compressibility of gases.

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4.7 Slow-Down of Pig Velocity In order to keep the velocity of the pig below the maximum permissible value (fig. 4.4), when the pig enters the receiving pig valve, two measures can be used:

a) Decreasing the flow rate of the pump

b) Using a by-pass The by-pass diverts a part of the volume flow around the pig valve, so that the volume flow through the pig valve is reduced and thus the pig velocity.

By opening or closing the by-pass valve, the velocity of the pig can be controlled. In order to permit sufficient control, the cross-section of the by-pass should be 25 to 50 percent of that of the pipeline.

By-pass Valve

By-pass

Pig Receiving Valve

Fig. 4.5 Slow-down of the pig velocity by a by-pass

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4.8 Operations with Trouble and Defects a) General If a direct dangerous situation arises during operation, e. g. by an unexpected reaction sequence or as a result of a dangerous effect from the outside, then the necessary counter measures are to be seized and if necessary the valve has to be put out of operation.

A special check of the valve is necessary, if during the operational disturbance the maximum allowable pressure was exceeded by more than 10%, the allowable operating temperature was considerably exceeded or the valve was damaged.

b) Trouble Shooting Guide With malfunctions the valve is to be examined first with the help of the following table:

Trouble Possible Causes Trouble Shooting Operation impaired (not operable, difficult to operate)

Pipeline clogged by solid components of the medium or solid bodies

Cleaning of the pipeline, disassembly and cleaning of the inner valve parts if necessary

Gears or actuator faulty Check gears and/or actuator Valve mechanically damaged by

overloading Disassembly and repair or replacement

Leakage of the body outward

Stem seal faulty Injection of secondary sealant (if scope of supply)

Replacing of the seals Leaky drain or pressure warning

devices Seal drain or pressure warning devices, if necessary replace valves

Bonnet seal faulty Disassembly and replacement of the bonnet seal

Leakage at the ball End stops of the actuator set wrong

Correction at the actuator

Contamination due to solid components of the medium or solid bodies

Cleaning of the pipeline, disassembly and cleaning of the inner valve parts if necessary

Seat ring seals faulty Injection of secondary sealant (if scope of supply)

Disassembly and repair or replaceLeakage at the pig trap closure

Closure seal faulty Replacement of the closure seal

c) Leakage test of seat ring seals A leakage test of the seat rings can be executed in full open or full closed position of the valve (double block and bleed function).

While the pipeline is under pressure, the drain device is slowly opened. After a stabilisation period it is then determined whether medium leaks out and the leakage is measured on the basis of bubbles or drops per minute.

d) Sealant injection (if scope of supply) With unacceptable leakages at stem seal or seat ring seals, suitable sealant is pressed into the relevant injection ports time by time, until the leakage disappears.

During sealant injection for the seat ring seals, the valve should be in 100%-closed position and the pipeline should be under pressure. So the sealant can spread best.

Recommended sealant, if no other medium is specified: VAL-TEX No. 80, multi purpose medium on hydrocarbon basis, proof against LPG and all aromatics, temperature range -50 to +260 °C.

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5 Maintenance With normal operation ITAG pig valves do not require special maintenance.

Standard gears for manual operation should be lubricated in regular intervals. With rough operating conditions (extreme temperatures, rough contamination etc.) a regular exchange of the transmission grease is recommended.

With all other gears and/or actuators (electrical, hydraulic, pneumatic) appropriate references of the manufacturers have to be regarded.

5.1 Storage The pig valve should be stored in dry, sheltered and ventilated areas. The ball of the valve should be in full open position, the pig trap closure closed and the ends should be closed by protective caps.

New un-used valves can be stored normally without additional actions. For longer storage however additional preservation actions are recommended.

For a longer putting out of operation and/or storage of used valves the corrosion protection is to be considered. Thorough cleaning and careful preservation of all parts, particularly after operating in aggressive media, are recommended.

5.2 Preservation After thorough cleaning and de-rusting, all inner surfaces with sliding function are to provide with high-viscous grease (e. g. grease on PTFE basis), all other inner surfaces are to provide with a preservation film (e. g. Tectyl® 2).

Damages of the exterior paint should be repaired.

2 Tectyl® is a registered trademark of Valvoline

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Notes:

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Valves & Oilfield Products

ITAG Valves & Oilfield Products GmbH Itagstrasse 5-17 29221 Celle Germany 6D-0053

6A-00767-1-0046

Phone +49 (0) 51 41-914-0 Fax +49 (0) 51 41-914-270

www.itag-celle.de [email protected]

Manuel Gare Itag

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