std spec fab erc

8/10/2019 Std Spec Fab Erc

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STANDARD

SPECIFICATION FOR

FABRICATION

AND

ERECTION OF PIPING


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CONTENTS

1. GENERAL

2. PRE-FABRICATION

3. ERECTION

4. LAYING OF UNDER GROUND PIPING

5. INSPECTION

6. TESTING

7. RECORDS

8. PAYMENT


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Std. spec for earth work for U/G pipingStd. spec. for weldingCode for petroleum Piping ANSI B 31.3/IS 10234

piping

Code of procedure for manual IS: 823Metal arc welding of mildSteel for structural work.

Welder qualification ASME Sec. IX

All codes referred shall be the latest editions. The contractor shall bear the cost of repair, changes,replacements etc. due to non-compliance with the standards, codes and the tender or due todisregard of the instructions given by the Engineer in charge.

2. PRE-FABRICATION

The contractor shall fabricate all pipe work in conformity with the requirements of pertinent generalarrangement drawing and specification. Where specific details of fabrication are not indicatedon the drawings or not specified herein fabrication and erection shall be done in accordance withthe code for petroleum refinery piping ANSI B 31.3 latest edition.

The contractor shall be reasonable for working to the exact dimensions as shown on the drawingsirrespective of individual tolerances permissible. Where errors and /or omissions occur on thedrawings, it shall be the contractors responsibility to notify the Engineer in charge prior tofabrication or erection. Dimensional tolerance for fabrication shall be as per standard.

1. GENERALThis specification is intended to cover the technical requirements for the execution of piping pre-

fabrication, assembly and erection of the entire pipe work defined hereunder for product /water pipe line.

2. Scope

-Fabrication and erection of all piping systems from piping materials supplied by owner inaccordance with this specification and applicable drawings and standards.-Testing and flushing-Fabrication and erection of supporting elements i.e. shoes, guides, stop anchors, clips, cradlesetc. including applying one coat of red oxide zinc chromate primer.-Fabrication and erection of supporting fixtures i.e. brackets, cantilever struts etc. includingapplication of one coat of red oxide zinc chromate primer.-Coating & wrapping of underground piping.-Fabrication and erection of drain assemblies.-All piping systems shall be fabricated, installed, flushed, and tested in accordance with thisspecification and applicable codes / drawings / standards. Any deviation from the specificationand drawing shall be permitted only after obtaining the written approval of the Engineer incharge.

Applicable Codes & StandardsStd. Spec. for coating and Wrapping of U/G piping.


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2.2 AlignmentThe pipes to be joined by welding shall be aligned correctly with the existing tolerances on

diameters, wall thickness and out of roundness. The same alignment shall be preserved duringwelding. For the internal misalignment due to difference in wall thickness of the matingcomponents exceeding 1/16, the component with the higher wall thickness shall be internallymachined / grounded as per standard, so that the adjoining surfaces are approximately flushed.

2.4 Layout, Cutting & Fitting-upFor laying out headers, tees, laterals and other irregular details, cutting templates shall be used to

ensure accurate cutting and proper fit up.

All cutting shall follow the outline of the templates.

Machine cut bevels to form the welding groove are preferred in carbon steel pipe. However,smooth, clean, slag free, flame cut bevel is acceptable.

Tack welds with full penetration shall be used and shall become the part of the finished weld.Defective welds or tack welds with lack of penetration are not acceptable and shall be chipped /ground out. No temporary weld attachment shall be with extended clamps / attachments.

2.5 Other alignment considerations

All flange facing shall be true and perpendicular to the axis of the pipe to which they are attached.Flange bolt holes shall straddle the normal centreLines unless different orientation is shown in drawings to match the equipment connections

etc.tolerances on fabrication shall be as per standard.

2.6 Mitre Bends & Fabricated Reducer

The specific application of welded mitre bends and fabricated reducers shall be governed by the piping material specifications to be furnished to the contractor. The angle of the each cutsegment shall be 15deg, 30deg, 30deg and 60deg for right angle bends (4 piece mitres).

The piping rates shall be inclusive of erection of mitre bends and fabrication of reducers.However, the contractor shall be paid separately for fabrication of bends where required.

2.7 Pipe jointsThe relevant piping class attached to each line specifies the type of pipe joints to be adopted in

construction in all piping systems. In general, joining for lines 2 and above in utility pipingsystem shall be accomplished by butt welding connections. Pipe lines 1 and below shall havesocket welded / butt welded / screwed joints as specified in the piping materials specifications.Butt welded joints shall be as per standard.

In general, flanged connections shall be used at connections to all equipment and where requiredfor ease of erection and maintenance purposes.

2.8 Cleaning of piping

On completion of fabrication, all pipes and fittings shall be cleaned inside and outside by suitablemeans (Mechanical cleaning tool, wire brush, etc.) before erection to ensure that assembly is freefrom all loose foreign material such as scale, sand, weld, spatter particles, cutting chips, etc.


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All field fabricated piping shall also be cleaned at the completion of the fabrication. All burrs,welding circles and weld spatter shall be removed by any suitable means (mechanical tools, wire

brush etc.)

Both shop and field fabricated piping shall be blown out with compressed air at the termination ofcleaning and capped.

Cleaning requirements for special services, if any, shall be as specified in the piping materialspecifications.

Performances of welds and heat treatment

All welding and heat treatment shall be performed in accordance with the welding specificationsdetailed elsewhere.

3. ERECTION

3.1 The intent of pre-fabrication at the shop is to accelerate progress of pipe work and to minimizeworking the field. Such pre-fabrication should be based on approved isometric and pipinglayouts furnished to the contractor. Field weld is indicated by FW on isometrics. Field weldmeans position weld of prefabricated piece at site or near the plant. However the contractor shall

bear in mid that there can be variations in dimensions between those appearing in the isometrics /layouts and those actually occurring at the site due to minor variations in the location ofequipment, inserts, etc. The contractor shall, therefore, provide adequate field joints, if required,other than shown in isometric and fit-in sections permitting the pre-assembly to be installedwithout any modification. In any case no extra clamps will be entertained on this account.

All piping shall be routed and located as shown in piping drawings keeping in view the pipingspecifications. No deviations from the arrangement shown shall be permitted without theexpress consent of the Engineer in charge.

a) While fitting up mating flanges, care shall be exercised to properly align the pipes and to checkthe flanges for trueness, so that faces of the flanges can be pulled up together without inducingany stresses at the pipes and equipment nozzles. The bolt holes of flanges in the vertical planeshall straddle the vertical centre line of the pipe in the erected position and for flanges in thehorizontal plane, the bolt holes shall straddle horizontal plane unless otherwise indicated on thedrawings

b) Flanged connections at the pump, turbines, compressors shall be made in such a way asnot to induce any stresses due to mis-alignment, excessive gap etc. The final tightening shall beredone when the machines are aligned completely and specifically authorized by the Engineer incharge. Temporary protective covers shall be provided at all flanged connections of pumps,compressors, turbines and other similar equipment until the piping is finally connected.

Slopes specified for various lines in the drawings shall be maintained by the contractor. In casethe contractor s unable to maintain the indicated slope he shall check the sagging of the pipe witha precision spirit level. Vents and drains are shown in the isometric of each line and these areintended, during hydrostatic test, for releasing the trapped air and draining out the test fluid aftertesting. Valved vents and drains are also shown wherever required. The contractor shall providevents and drains connections even when these are not shown in the drawings and are found


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necessary by the Engineer in charge for process lines. The details for the type of connections to be adopted shall be given to the contractor at the time of work.

After the piping is erected in final position, it shall be cleaned, tested for tightness and kept drywherever instructed, as described in this specification.

Valves

The valve spindle positions are shown in the arrangement drawings and the contractor shall berequired to follow them. He shall, however, bring it to the notice of the Engineer in charge incase he encounters some difficulty in installing them.

Where practicable and except when otherwise shown on the drawings, valve stems shall beinstalled in a vertical direction and shall not be installed with stems below the horizontal axis.

Supports

Supports, guides and anchors for piping shall be fabricated and provided as shown in thedrawings. No anchors on piping shall be used except at locations shown in the drawings. The

pipe shall be secured firmly at anchor supports.Fabrication and erection of supporting elements and structural fixtures wherever required and pointed out by the Engineer in charge, whether indicated in drawing or not, to prevent vibration,excess sag etc. shall be carried out by the contractor. No separate payment will be made forerecting of these additional supports and it will be deemed as part of piping erection work.

4. LAYING OF UNDERGROUND PIPING

The Contractor shall lay the underground piping in accordance with the following clauses and as per the piping arrangement drawings/stetches issued during the course of construction. Coatingand wrapping of the underground lines shall be in accordance with specification.

The contractor shall dig the pipe line trenches where necessary according to the drawing, true tothe line and gradient as per specifications and as directed by the Engineer-in-charge.

The contractor shall be responsible for correct layout and gradient of the line. Errors, if any, shall be rectified by the Contractor at his own cost.

Trenching: (Refer specification for Earthwork in underground piping)

The trench shall be cut true to the line leveled with the help of sight rails provided at every 30 M atchange of direction, gradient and at any suitable distance as directed by Engineer in charge.

If the trench is excavated below the required level indicated in the drawing, the extra depth shall be filled with concrete or approved equivalent material as directed by the Engineer in charge atno extra cost to owner.

The trench shall be excavated so as to provide an average cover of 1000 mm or equal to thediameter of the largest pipe to be laid in the trench, or as shown in drawings whichever is greater.The average cover will be reckoned from top of the pipe of the largest diameter to be laid in thetrench, to the finished grade. The width of the trench shall be sufficient to give free working


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space on each side of the pipe. The free working space shall conform to IS: 783. Generally itshall not be less than 150 mm on either side or 1/3 of dia of pipe whichever is greater.

No excavated material shall be deposited within 1.5 metres from the excavated trench.

In case of road cutting, all material, i.e. metal, bricks etc. shall be taken out carefully and keptseparately for reuse and road work shall be redone upto the original level prior to cutting the roadwith the excavated road materials after laying and testing of the pipe line within 10 days from thedate of starting the work at the cost of the contractor. The contractor shall provide suitable singsand barricades to prevent accidents. He shall also provide reasonable by pas at his own costwhen a road is cut for laying pipeline.

During excavation, if some obstacle is met with, the same shall be reported to the Engineer incharge and dealt with as instructed by him.

The contractor shall dewater, shore or do whatever might be required to excavate the trench, installthe pipe in it and backfill the trench, in accordance with the specifications at no extra cost to theowner. Dewatering shall be done in advance of the laying of the pipe to allow adequateinspection of padding of the bottom if required and dewatering shall be continued throughoutduring laying of the pipe an backfilling of the trench.

In muddy slushy ground, the bed shall be provided with a layer of a sand or lean concrete asdirected by the Engineer in charge.

The trench shall follow the gradient of pipeline as specified in the drawing. The contractor shallkeep the trench in good condition. Until the pipe is laid and tested, no extra claim shall beentertained due to its caving or setting down either before or after the pipe is laid. All materialsto shore the trench in order to prevent caving are to be furnished and removed by the Contractorat no extra cost to the owner.

In case pipe is lowered in caved trench and back filled before being inspected by the Engineer incharge, the contractor shall re-excavate the trench, for inspection and backfill it at his own cost.

5.0 Lowering and laying

The pipe shall be lowered either by mechanical method or by hand when the trench is ready and bottom of the trench is graded as per required pipe laying conditions and specifications.

5.1 By Machine

The shop coated pipe, already transported to the pipe laying site / convenient length of pipassembly coated and wrapped near the trench after hydrostatic testing shall be placed on cleansquare cut skids suitably spaced so as to keep the pipe way from touching the ground. The pipemay be lowered down in the trench by the launcher cranes, with sufficient care to protect thecoating and wrapping of the pipelines.

At tie in welds and other places, the contractor shall clean, prime, coat and wrap manually. Alsoshort sections of pipelines which are impracticable to shop treat may be hand treated but only onthe prior written approval of the Engineer in charge.


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5.2 By Hand

The pipe may be lowered with the help of tripods and chain pulley blocks into the trenchimmediately after the coating and wrapping. However, if in the opinion of the Engineer incharge that the temperature conditions do not allow direct lowering, then the pipes shall be setdown on clear square cut skids. The skids shall be so spaced as to keep the pipe away fromtouching the ground.

Method & Time of Lowering Pipe

Under favourable temperature, conditions and using methods which will not damage coating, the pipe may be lowered into the trench.

Pipe previously set on skids, because of un-favourable temperature conditions shall be loweredinto the trench normally in the cool of the morning and only when the temperature of the pipe is

below the softening point of the coating materials.All skid marks and other places of damage shall be thoroughly examined to ensure proper patching

where necessary, before the pipe is finally lowered into the trench.

6.0 Handling coated pipe

Coated pipe shall not be placed in trench until cave in plugs, hard clods; stones, skids, weldingrods etc. have been removed there from. Where the trench has a hard or jagged bottom,sufficient fine dirt or sand shall be placed therein, before the pipe is lowered.

Coated pipe shall not be handled or moved by means of cable or chains or by praying with skidsor bars, it shall be tightened and lowered by using lowering in belts of a standard width anddesign for the size of pipe being handled.

Coated pipe shall not be dragged along the ground or otherwise handled in a manner that will bedetrimental to the coating.

Lining up and welding

The ends of the pipe line shall be kept securely closed to prevent entry of any foreign material /moisture after lowering into the trench.

Before making joint, the pipe shall be carefully laid so as to be perfectly aligned in both plan and profile, and the end closure provided shall be removed. Tie in shall be made in the coolness ofthe morning or when the ambient temperature is not exceeding 29 deg C or softeningtemperature of the coating material whichever is less. All beveling aligning and welding shall bein accordance with the welding specification given in the tender.

Free access shall be provided for the welding of the circumferential joints by increasing the widthand depth of the trench at these points. There should be no construction to the welder from anyside so that good welded joint is obtained.

Testing & coating wrapping


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The completed system shall then be tested as per clause 6 and the field welded joints coated andwrapped as per specification.

7.0 Back Filling

After testing and inspection of the pipeline to the entire satisfaction of the Engineer in charge, thetrench shall be back filled with the excavated material. No trench shall be back filled without theapproval of the Engineer in charge. Backfilling with the excavated material shall be done inlayers of 200 mm well watered and rammed to avoid any settling afterwards.

The contractor shall place soil over the trench to such a height as well as in opinion of the Engineerin charge, to provide adequately for future settlement of the trench backfill.

If due to exigencies of the work, some portion of the pipeline is backfilled without approval of theEngineer in charge, the engineer in charge shall have the right to order uncovering of the pipe forexamination and the cost of such uncovering shall be borne by the Contractor.

The backfill material shall free from stone pieces.

Surplus excavated soil or rubbish material shall be removed by the Contractor at his own cost to a place designated by the Engineer in charge.

When the trench has been dug through roads, all backfill shall be thoroughly compacted. Incertain cases, special compaction methods may be required by the Engineer I charge. This shall

be done by the contractor at no extra cost to the owner.

When the trench has been dug through unlined ditches the backfill shall be thoroughly compactedin 150 mm layers for a distance of 1.50 m beyond the outside banks of the ditch on either side.The banks of the ditch shall also be compacted in 150 mm layers at no extra cost to the owner.

After the roads have been already graded and if they are trenched or otherwise disturbed by theContractor during laying of the pipe lines, the contractor shall restore the road to its original leveland condition. In the event, the contractor is required to place extra fill, gravel, or other specialmaterials it shall be done by him without any extra cost to the owner.

Clean up of surroundings

As soon as the backfill is completed, the contractor shall immediately clean up the adjoining area by removing all surplus and defective material and dispose of all refuse such as spurs, sheet-iron, broken skids, etc. to the complete satisfaction of the Engineer in charge.

The earth on both sides of the pipeline trench which has been disturbed during the construction ofthe pipe line shall be smoothened and left in a condition satisfactory to the Engineer in charge.

8.0 INSPECTION

General

Owners inspector shall have free access to all places where the work is being done or any otherthing and place concerned with the work.


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Owner is entitled to send his own inspector, to field or shops where pre-fabrication and erection of pipe lines are being done, with the following functions but not limited to :

i) To check that the welding performance and welding equipments used on the job are suitable andconform to relevant standards.

ii) To supervise welding procedure qualification.iii) To supervise welder performance qualification.iv) To check whether welding is conforming to relevant specification and the practice

construction practice.

To check any other performance to ensure quality of work.

Contractor shall notify sufficiently in advance the commencement of qualification tests, weldingwork and acceptance tests, to enable the Owners Inspector to supervise the same.

Contractor shall provide the Owners Inspector with all facilities necessary for carrying out hiswork at no extra cot to the owner.

Approval from the Owners Inspector shall not relieve the contractor partially or fully of hisresponsibilities and guarantees under this contract.

Visual Inspection

Inspection of all welds shall be carried out as per ANSI B 31.3. Finished welds shall be visuallyinspected for parallel and axial misalignment of the work, cracks, inadequate penetration, unrepaired burn-through, dimensions, and other surface defects, and it shall present a neat workmanlike appearance. Under cutting adjacent to the final bead on the outside of the pipe shall notexceed 0.8 mm in depth of 12 % of the pipe wall thickness, which ever is smaller and thecumulative length shall not be more than 50 mm in any continuous 300 mm length of weld.

Repairs or removal of defects

Defects which are not within the acceptable limits shall be removed from the joint completely bychipping or grinding.

When the whole joint is found unacceptable, the weld and the ends of the joints shall be restoredaccording to relevant clauses under fabrication.

No repair shall be carried out without prior authorization of the Engineer in charge.

9.0 TESTING

General

The field test pressure shall not be less than the greatest of the following:

a) 1 times the maximum sustained operating pressure. b) 1 times the maximum pipeline static pressure and

Sum of the maximum sustained operating pressure or the maximum pipe line static pressure andthe maximum calculated surge pressure.


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The field test pressure shall wherever possible be not less than two thirds of the works test pressure and shall be applied and maintained for at least four hours.

Where the field test pressure is less than two thirds the works test pressure, the period of test shall be increased to at least 24 hours. The test pressure shall be gradually raised at the rate of nearlykg / cm 2 / minute.

All underground / above ground pipes shall be tested for leakages to a minimum hydrostatic test pressure of 10 kg/ cm2 gauge.

The testing shall be carried out in convenient section as approved by the Engineer in charge. The joints of the pipe connecting the testing sections shall be 100% radiographed.

If some defect is noticed during the hydrostatic testing, the same shall be brought to the Notice ofEngineer in charge. Joints, if leaking, shall be rectified as per the welding specifications andinstructions of engineer in charge and tested to his satisfaction at no extra cost to the owner.

The engineer in charge shall be notified in advance by contractor of all testing. The hydrostatictesting / flushing of all the piping shall be carried out by the contractor at his own cost.

Contractor shall make his own arrangements for flushing at suitable points as per the instructionsof the Engineer in charge. Any extra work / modification on this account shall be done by thecontractor at his own cost.

Test mediumConstruction water shall generally be used as the testing medium for the hydrostic testing of piping system.

CleaningAll systems shall be cleaned and flushed free of all dirt, debris or loose foreign material after

testing.

Temporary BlindsOpen ends of piping systems such as a pumps or wherever equivalent has been removed or

disconnected prior to hydrostatic testing, or at termination point of piping branch connectionsshall be blinded of by temporary blind flange made out of 10 mm thick M.S. plate.

Venting:All piping systems and equipments shall be properly vented to remove air from system during

filling.

PressurizingPressure shall be applied by means of a suitable test pump which shall not be connected to the

system until ready to test. A pressure gauge shall be provided at the pump discharge forguidance in bringing the system upto pressure. The pump shall be attended to constantly duringthe test by an authorized operator. The pump shall be disconnected after the pressure test iscompleted.


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The test pressure is to be maintained for sufficient time to permit complete inspection of thesystem under test but in no case shall the time be less than ten minutes. Test shall be consideredcomplete only when approval is given by the Engineer in charge.

Test Gauges:

Contractors own test gauge shall be installed as close as possible to the lowest point in the system being tested. Prior to installation, the test gauge shall be checked against a standard gauge orcalibrated with the aid of a dead weight tester. Calibration of test gauges shall be theresponsibility of the contractor.

Draining

All lines and equipments shall be completely drained after the hydrostatic test of a system has been completed. High point vents shall be open to prevent excessive vacuum and permitcomplete draining.If it becomes necessary to leave a system filled with the testing medium forany abnormal length of time, such as venting shall be made to provide for possible liquidexpansion with change in ambient temperatures.

10.0 RECORDS

Records in triplicate shall be made for each piping system as follows:

10.1 In case of underground piping, layouts giving actual elevations or pipeline as laid.

10.2 Test certificates containing date or test, identification of the piping system, test fluid used, test pressure and approval of owners inspector.

Certificates for flushing containing flushing medium used, identification of the piping system, dateof flushing and approval by owners inspector.

PAYMENT

Payment for piping shall be based on linear measurements calculated on the basis of the executiondrawings. The length shall be measured along the centre lines of pipes, centre lines of bends andelbows, tees, reducer, SW, flanged joints. All types of valves shall be excluded from thismeasurement. Branch connections shall be measured from the outer surface of the header.

The payment shall be made on per metre basis of piping work erected, measured to the nearestcentimeter.

The unit rates for the underground piping shall be inclusive of earthwork excavation, backfilling,and compaction, disposal of surplus earth, coating and wrapping including supply of materials.

The unit rates for above ground carbon steel piping shall be exclusive of erection of all types ofsupports but inclusive of supply of necessary bolts nuts and washers gaskets etc as per respectivespecification.

Payment for the installation of sluice valves, check valves, butterfly valves, expansion bellowswill be made on number basis and the unit rates shall be inclusive of supply of necessary boltsnuts, washers and gaskets, etc.


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All piping attachments, such as coupling, nipples, thermo wells etc. shall be installed by theContractor as per the piping work and no separate payment shall be made for such work.However, extension on such attachments such as vents and drains will be measured and paid asapplicable for the respective size and category of piping / valves.

Fabrication of mitre bend, concentric and eccentric reducers fabricated from pipes supplied byowner, and fabrication of flanges from plates supplied by owner, will be paid at respective unitrates. However, erection of these items will be along with piping of the respective size and noseparate payment will be made for erection. The reducers will be measured and paid along withthe piping of large diameter.

No separate payment will be made for making pipe to pipe branch connection crosses with orwithout reinforcing pads and the unit rates for piping are deemed to include all such work.

Fabrication, installation and removal of temporary spool pieces etc. to aid contractors work suchas fabrication, erection, flushing testing, and etc. will neither be measured nor paid separately.The same is deemed to be included in the unit rates for piping.

Payment for carrying out radiographic examination shall be based on linear length of the welded joint radiographed. Repeat radiography / additional radiography required due to contractorsfault / poor performance of his welders, defective films shall be done at contractors own cost.

WELDING SPECIFICATION FOR THE FABRICATION OF PIPING(Above Ground Portion)

1. GENERALThis specification shall be followed for the fabrication of all types of welded joints ofcarbon steel and alloy steel piping system within the battery limits of the plant.

The welded pipe joints shall include the following:

a) All pipe joints of the longitudinal and circumferential butt welded and socket weldedtypes.

b) Attachments of forgings, flanges and other supports to pipes.c) Welded manifold headers and other sub-assembliesd) Welded branch connections with or without reinforcing pads.e) Joints in welded / fabricated piping components.f) The attachments of smaller connections for vents, drain drips and other instrument

tappings.

Any approval granted by the Engineer-in-charge or Owner's inspector, shall not relieve theContractor of his responsibilities and guarantee.

This specification shall not be applicable for welding of pipelines for transportation of liquid petroleum and other similar products.

2. APPLICATION CODES &STANDARDS :All welding work, equipments for welding, heat treatment, other auxiliary functions and thewelding personnel shall meet the requirements of the latest editions of the following expectedstandards and procedures unless otherwise specified in the Welding specification chart and


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the technical notes attached. In the case of conflicting requirements, the requirementsmentioned in welding specification chart / Technical Notes shall be applicable.

a) Chemical Plant and Petroleum Refinery Piping - ANSI:B31.3 b) The Indian Boiler Regulations - I.B.R.

relevant code of fabrication shall be followed for the welding procedures.

i. Welding and Brazing Qualifications ASME Sec IX.ii. Non destructive examination ASME Sec. Viii. Material Specifications : welding rods, Electrodes and filler metals ASME Sec II Part

C

In the event of any differences due to the additional requirements mentioned in this specification, overand above those obligatory as per codes, this specification shall be binding.

3. BASE METAL:

3.1 In general, use of carbon steel, alloy steel and stainless steel are envisaged. The details ofthe material specifications are given in the welding specification chart.

3.2 The contractor shall provide the manufacturer's test certificates for every heat of thematerials supplied by him.

4. WELDING CONSUMABLES

4.1 The contractor shall provide, at his own expense, all the welding consumables necessary forthe execution of the job such as electrodes, filler wires, oxygen, acetylene, argon etc, andthese should bear the approval of the Engineer-in-charge.

4.2 The welding electrodes and filler wires supplied by the Contractor shall conform to the classspecified in the welding specifications chart. The materials shall be of the make approved

by the Engineer-in-charge.4.3 Electrode qualification test records should be submitted as per the Exhibit A (attached) in

respect of the electrodes tested by the Contractor, for obtaining the approval of the engineer-in-charge.

4.4 The contractor shall submit batch test certificates, from the electrode manufacturers, givingdetails of physical and chemical tests carried out by them, for each batch of electrode to beused.

4.5 All electrodes shall be purchased in sealed containers and stores properly to preventdeterioration. The electrodes removed from the containers shall be kept in holding ovens attemperatures recommended by the electrode manufacturer. 'Out of the oven time' onelectrodes, before they are consumed shall not exceed the limits recommended by theelectrode manufacturer. The electrodes shall be handled with care to avoid any damage tothe flux covering.

4.6 All low hydrogen tupe of electrodes shall be rebarked at 350 0 C for 1 hour minimum andstored in ovens kept at 80-100 0C before use. Recommendations of the electrodemanufacturer shall be followed if available.

4.7 The electrodes, filler wires and flux used shall be free from rust, oil, grease, earth and otherforeign matter which affect the quality of welding.

4.8 Tungsten electrodes used shall conform to SPA 5.12 specification.


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5. SHIELDING & PURGING GAS :

5.1 Argon gas used in GTA welding for shielding purpose shall be 99.995% pure. The purity ofthe gas shall be certified by the manufacturer. The rate of flow shielding purpose shall beestablished through procedure qualification tests. Normally this rate may be 12-20 CFH.

5.2 Argon gas with a purity level of 99.995% shall be used for purging.5.3 When GTAW process alone or a combination of GTAW processes is recommended for the

production of a particular joint, the purging shall be maintained during the root pass and forthe first filling pass to minimize oxidation on the inner side of the pipe, unless otherwisespecified in welding specification chart.

5.4 Initial purging shall be maintained for sufficient period of time so that at least 4-5 time thevolume between the dams is displaced, in order to completely remove the entrapped air. Inno case should the initial purging period be less than 10 minutes. High gas pressure should

be avoided.5.5 After initial purging, the flow of the backing gas should be reduced to a point where only a

slight positive pressure prevails. For systems which have a small volume ( upto cubicfoot) to be purged, a gas flow rate of 6-CFH is usually adequate. Systems of larger volumemay require higher flow rates and these should be established procedure qualification tests.

5.6 Gas backing (purging) is not required for socket type of welded joints.5.7 Dams, used for conserving inert gas during purging, shall be removed after completion of

the welding, and shall be accounted for. Wherever, removal of dams is not possible afterwelding, use of water soluble dams should be made.

2. EQUIPMENTS & ACCESSORIES :

6.1 The contractor should have the arrangement of sufficient number of welding and cuttingequipments, auxiliaries, and accessories of sufficient capacities so as to meet the target/schedule.

6.2 All the equipments for performing the heat treatment, including transformers, thermo-couples, pyro-meters, automatic temperature recorders with suitable calibrationarrangements etc. shall be provided by the Contractor at his own expense and these should

bear the approval of the Engineer-in-charge.6.3 Contractor shall make necessary arrangements at his own expense for providing the

radiographic equipments, radiographic films, and all the equipments / materials required forcarrying out the dye-penetrant/ magnetic particle test for satisfactory and time completion ofthe job.

6.4 Redoing of any work necessitated by faulty equipments or operaion used by the Contractor,will be done at his own expense.

3. WELDING PROCESSES :

7.1 Welding of various materials under this specification shall be carried out using one or moreof the following processes with the approval of the Engineer-in-charge.

- Shielded Metal Arc Welding Process (SMAW)- Gas Tungsten Arc Welding Process (GTAW).

7.2 The welding processes to be employed are given in the welding specifications chart. Anydeviation desired by the contractor shall be obtained through the express consent of theEngineer-in-charge.


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7.3 Automatic and semi-automatic welding processes shall be employed only with the expressapproval of the Engineer-in-charge. The welding procedure adopted and consumables usedshall be specifically approved.

7.4 A combination of different welding processes could be employed for a particular joint onlyafter duly qualifying the welding procedure to be adopted and obtaining the approval ofEngineer-in-charge.

4. EDGE PREPARATION :

8.1 The edges to be welded shall be prepared to meet the joint design requirements by any ofthe following methods recommended.

a. Carbon SteelGas cutting, machining or grinding methods shall be used. After gas cutting, oxides

shall be removed by chipping or grinding. b. Low Alloy Steels (containing upto 2 chromium):

Gas cutting, machining or grinding methods shall be used. After cutting, machining orgrinding shall be carried out on the cut surface.c. High alloy steels, cupro-nickel, nickel alloys, and aluminium alloys:

Plasma cutting, machining or grinding methods shall be used. After plasmacutting, cut surfaces shall be machined or ground smooth.8.2 Cleaning-a. The ends to be welded shall be properly cleaned to remove paint, oil, grease, rust, oxides,

sand, earth and other foreign matter. The ends shall be complete dry before the weldingcommences.

b. On completion of each run, craters, welding irregularities, slag etc., shall be removed bygrinding and chiseling. Wire brushes used for cleaning stainless steel joints shall havestainless steel wires and the grinding wheels used for grinding stainless steel shall be ofsuitable type. Separate grinding wheels and wire brushes should be used for carbon steelsand stainless steel.

9. ALIGNMENT & SPACING :

9.1 Components to be welded shall be aligned and spaced as per the requirements laid downin applicable code. Special care must be taken to ensure proper fitting and alignmentwhen the welding is performed by GTAW process. Flame heating for adjustment andcorrection of end is not permitted unless specifically approved by the engineer-in-charge.

9.2 A wire spacer of suitable diameter may be used for maintaining the weld root openingwhile tacking, but it must be removed after tack welding and before laying the root bead.

9.3 For pipes of wall thickness 5mm and above, the ends to be welded shall be secured in position with the aid of couplers; yokes and 'C' clamp to maintain perfect alignment.Yokes shall be detached after the completion of weld, without causing any surfaceirregularity. Any irregularity caused on the pipe surface must be suitably repaired tosatisfaction of the engineer-in-charge.

9.4 Tack welds, for maintaining the alignment, of pipe joints shall be executed carefully andshall be free from defects. Defective tack welds must be removed prior to the actualwelding of the joints.

9.5 Tacks should be equally spaced. Minimum number of tacks shall be2 tacks for 2 '' and smaller dia pipes4 tacks - for 3" to 12'' dia. pipes6'' tacks for 14'' and larger dia pipes


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12. HEAT TREATMENT :

12.1 Preheatinga) No welding shall be performed without preheating the joint to 10 (50F) when the ambient

temperature is 10 and below. b) Preheating requirements for the various materials shall be as per the welding specification

chart attaches.c) Preheating shall be performed using resistance or induction heating methods. Preheating by

gas burners, utilizing oxy-acetylene or oxy-propane gas mixtures, with neutral flame mayalso be carried when permitted by the Engineer-in-charge.

d) Preheating shall extend ununiformly to at least three times the thickness of the joint, but notless than 50 mm, on both sides of the weld.

e) Preheating temperature shall be maintained over the whole length of the joint duringwelding. Temperature indicating caryons of other temperature indicating devices shall be

provided by the contractor to check the temperature.

12.2 Post HeatingIn case of alloy steel materials such as Cr-Mc steels, if the Post We Heat Temperature is not

performed immediately after welding, the weld joint and adjacent of pipe, at least 150mm oneither side of weld, shall be uniformly heated to 300C. This temperature shall be maintained for2 hours minimum, then wrapped in asbestos or insulating before allowing it to cool to roomtemperature, postweld Heat Treatment as specified in the Welding Specification Chart shall becarried out later on.

12.3 Postweld Heat Treatmenta) Post weld Heat Treatment, wherever required for joints between pipes, pipes and fittings,

pipe body and supports shall be carried out as per the welding specification chart, applicablecodes standards and the instructions of the Engineer-in-charge.

b) The contractor shall submit for the approval of the Engineer-in-charge, well before carryingout actual Heat Treatment, the details of the post weld Heat Treatment procedure as perExhib B attached, that he proposes to adopt for each of the material assembly/ part involved.

c) Post weld Heat Treatment shall be done ina furnace or by using and electric resistance orinduction heating equipment, as decided by the Engineer-in-charge.

d) While carrying out local post weld Heat Treatment, technique of application of heat mustensure uniform temperature attainment at all points of the portion being heat treated. Careshall be taken to ensure that width of heated band over which specified post weld HeatTreatment temperature attained is at least that specified in the relevant applicablestandards/codes.

e) Throughout the cycle of heat treatment, the portion outside the heated band shall be suitablywrapped under insulation so as to avoid any harmful temperature gradient at the exposedsurface of pipe. For this purpose temperature at the exposed surface of pipe should not beallowed to exceed 400C.

f) The temperature attained by the portion under heat treatment shall be recorded by means ofthermocouple pyrometers. Adequate number of thermocouples should be attached to the

pipe directly at equally spaced locations along the periphery of the pipe joint. The minimumnumber of thermocouples attached per joint shall be 1 upto 6'' dia, 2 upto 10'' dia and 3 for12'' dia and above. However, the Engineer-in-charge can increase the required minimumnumber of thermocouples to be attached if found necessary.


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g) Automatic temperature recorders which have been suitably calibrated should be employed.The calibration chart of each record should be submitted to the Engineer-in-charge prior tostarting the Heat Treatment operations and his approval should be obtained.

h) Immediately on completion of the Heat Treatment, the post weld Heat Treatmentcharts/records along with the hardness test resulted on the weld joints, wherever required as

per the Welding Specification chart, shall be submitted to Engineer-in-charge for hisapproval.

i) Each joint shall bear an identification number which shall be maintained in the piping sketchto be prepared by the Contractor. The joint identification number should appear on thecorresponding post weld Heat Treatment charts. The chart containing the identificationnumbers and piping sketch shall be submitted to the Engineer-in-charge in suitable folders.

13. CLEANING OF THE WELD JOINTAll weld joints shall be free from adherent weld spatters slag, swarf, dirt or foreign matter. This can

be achieved by brushing. For stainless steel, brushes with only stainless steel bristles should beused.

14. INSPECTION AND TESTING

14.1 General

a) The owner's inspector shall have free access to all concerned areas, where the actualwork is being performed. The contractor shall also afford the Owner's Inspector allmeans and facilities necessary to carry out inspection.

b) The owner is entitled to depute his own inspector to the shop or field where prefabrication and erection of pipe lines are being done with (but not limited to) thefollowing objectives.

i. To check the conformance to relevant standards and suitability of variouswelding equipments and the welding performance.

ii. To witness the welding procedure qualificationiii. To witness the welder performance qualificationiv. To check whether shop/field welding being executed is in conformity with the

relevant specifications and codes of practice followed in piping construction.

c) Contractor shall intimate sufficiently in advance the commencement of qualificationtests, welding works and acceptance tests to enable the Owner's inspector to be

present to supervise them.

14.2 Welding Procedure QualificationWelding procedure qualification shall be carried out in accordance with the relevantrequirement of ASME Sec. IX latest edition or other applicable codes and the jobrequirements. The contractor shall submit the latest welding procedure specifications informat as per Exhibit-C (attached) immediately after the receipt of the order.

by the owner's Inspector shall be employed for welding. Contractor shall submit thewelder qualification test report in the format as per Owner's inspector will review, checkand approve the welding procedure submitted for his approval immediately aftercompleting the procedure qualification test and at least 2 weeks before thecommencement of actual work. Standard tests as specified in the code shall be carried


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out in all cases. In addition to these tests, other tests like macro/micro examination,hardness tests, dye penetrant examination, charpy V-notch and U-notch impact test etcshall be carried out on specimens depending upon the ytpe of base matter operatingconditions and requirements laid down in the detailed drawings and specifications. Itshall be the responsibility of the Contractor to carry out all the tests required to thesatisfaction of the Owner's inspector.and shall release the procedure for qualification tests. The procedure qualification testshall be carried out by the Contractor at his own expense. A complete set of test resultsin format as per Exhibition attached shall be submitted to the owner's inspector14.3 Welder's Qualificaton

a) Welders shall be qualified in accordance with the ASME Section IX orother applicable codes. The owner's inspector shall witness the test andcertify the qualification of each welder. Separately only those welders whohave been approved Exhibit E (attached) and obtain express approval

before commencement of the work. It shall be the responsibility ofContractor to carry out qualification tests of welders. For welding of theonly those welders with IBR Certifications, qualified by Boiler Inspectorate,and acceptable to the local Boiler Inspector authority shall be employed.

b) The welders shall always have in their possession the identification card asshown in Exhibit G and shall produce it on demand by the Owner's inspector.It shall be the responsibility of the Contractor to issue the identity cards after ithas been duly certified by the Inspector.

c) No welder shall be submitted to work without the possession of identity card.d) If the welder is found to perform a type of welding in a position for which he

is not qualified, he shall be debarred from doing any further work. All welds performed by an unqualified welder shall be cut and redone by a qualifiedwelder at the expense of the Contractor.

14.4 Visual Inspection

Inspection of all welds shall be carried out as per the latest editions of the applicable codesand specifications. All finished welds shall be visually inspected for parallel and axialalignment of the work, excessive reinforcement, concavity of welds, shrinkages cracks,inadequate penetration, unrepaired burn-through, under cuts, dimentions of the weld,surface porosity and other surface defects. Undercutting adjacement to the completed weldshall not exceed the limits specified in the applicable standard/code.

14.5 Radiographic Examinationa) The Radiographic Examination procedure to be adopted shall be submitted by the

Contractor as per Exhibit-P and shall be got approved by the Owner's Inspector priorto employment. The radiographic technique and procedure adopted shall conform tothe requirements mentioned in Article 2, as well Article (SE94, SE 142) of ASME SecV. The IQI sensitivity obtained shall be equal to or better than the requirementsmentioned in table 262.2 and table 272 of Article 2 of ASME Sec V for single walland double wall radiography respectively. Source side procedure/technique. Theacceptable limits of defects and removal of defects shall be as per the relevant codes offabrication. The contractor shall be responsible for carrying out Radiography,rectification of defects and re-radiography of welds repaired/rectified.


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b) The extent of Radiography shall be as per specifications to be supplied to theContractor. For welds between dissimilar materials, the extent of RadiographicExamination for the materials being welded. Wherever random Radiography is calledfor in a particular piping class, the dissimilar materials weld joint shall essentially beincluded.

c) Radiographic Examination shall be carried out using X-Radiation, Gamma ray sourcesmay be used in place of X-ray with the approval of the Owner's inspector.

d) The contractor shall fulfill all the statutory safety requirement while handling X-rayand Gamma-ray equipments.

e) The joints for Radiography shall be selected by the Owner's Inspector and theRadiography shall be performed in his presence. The contractor shall furnish all theradiographs to the owner's Inspector immediately after processing. The details of theradiographs along with the joint identification number shall be duly entered in aregister and signed by the Contractor and shall be submitted to the Owner's Inspectorfor approval.

f) The contractor shall provide the Inspector all the necessary facilities at site such as adark room with controlled temperature, film viewer etc. to enable him to examinethe radiographs.

g) Where random radiography is specified, the first weld of each welder shall becompletely radiographed. In the case of pipe of sizes 6'' and below, the first two weldsshall be completely radiographed.

h) For each weld performed by a welder, found unacceptable two additional checksshould be carried out on welds performed by the same welder. This operation isiterative and the procedure of radiographing two additional welds for each welddeemed unsatisfactory shall be continued till such time that the two consecutive weldsof satisfactory are found for every defective weld.

14.6 Liquid Penetrant and Magnetic Particle Examinationa) Whenever such tests are specified, the tests shall be carried out on joints chosen by the

Owner's inspector, as per ASME Section V article 6 and 7 respectively. b) For austentic stainless steels and other nonmagnetic materials, liquid (dye) penetrant

test shall be carried out. For carrying out this test, the materials shall be brought withina temperature limit of 15 to 50C.

14.7 Hardness TestHardness required for welds shall be as per the welding specification chart (attached).Hardness testing shall be carried out by Vickers Hardness Tester during welding procedurequalification. In all other cases hardness testing may be carried out by Vickers, Brinnel, orPoldy hardness tester as agreed by the Owner's Inspector.

14.8 Proof TestsHydrostatic and pneumatic tests shall be performed as per the requirement laid down byrespective flushing and Testing specification/applicable codes to demonstrate thesoundness of the welds. The tests shall be conducted after fulfilling the requirement ofvisual examinations radiography etc., and after the entire work has been certified by theOwner's inspector to be fit for being subjected to such tests.

15.0 REPAIRS OF WELDSa) Defects ascertained, through the inspection methods, which are beyond acceptable limits shall

be removed after the joint is completely radiographed by the process of chipping and grinding.


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b) When the entire joint is judged unacceptable, the welding shall be completely cut and the edges be suitably prepared as per required alignment tolerances. The rewelded joint shall again beexamined following standard practices.

c) No repair shall be carried out without prior permission of the Owner's inspector.d) Repairs and / or work of defective welds shall be done in time to avoid difficulties in meeting

the construction schedules.

16.0 DOCUMENTS TO SUBMITTED BY CONTRACTOR (4 COPIES EACH)

a) Electrode and Welding Consumable Qualification Records as per Exhibit-A, for the WeldingConsumables tested and approved for the work.

b) Batch test Certificates, for the Electrodes used, obtained from the Electrode Manufacturer.c) Proposed Heat Treatment Procedure as per Exhibit-Bd) Heat Treatment Chartse) Weld joint hardness test resultsf) Welding Procedure Specifications as per Exhibit-C immediately after receipt of the order.g) Welding Procedure Qualification records as per Exhibit-Dh) Welder Performance Qualification records as per Exhibit-E immediately after conducting welder

qualification tests.i) Radiography Procedure as per Exhibit-F

j) Radiographic test Report alongwith Radiographs.Pipeline Sketch (Isometric) giving all the details regarding the pipe specifications, welded joints, jointsradiographed, joints heat treated, electrodes used, welders identification number etc

std spec fab erc

Documents