Piping Fabrication and Erection Specification 

This content provides you with a sample Piping Fabrication and Erection Specification that is useful for field inspectors. 

1- General 

Piping Fabrication and Erection Specification

This specification covers the minimum basic requirements for various aspects of the above ground piping and in trench piping for the industrial plants as follow: 

The piping and fabrication inspection is covered in the I4I Academy API Source Inspector course and through ASME B31.3 which is part of this course. Other related I4I Academy course is API 570 piping inspector course. The ASME B31.3, ASME Section V and ASME Section IX  is part of API 570 course. 

a)       Shop and filed fabrication and erection of piping.

b)       Installation of in-line instrument items like orifice flanges, control valves, rota meters, safety valves, etc.

c)        Installation of items like line mounted filters, ejectors sample cooler, etc.

d)       Installation of expansion joints.

e)        Fabrication & erection of pipe supports including installation of spring supports, etc. both shop and field fabrication include cutting, threading, bending, welding, bolting, etc.

Administration of material certificates, welding operations and execution, administration of all destructive & non-destructive examination and all testing operations as required by the applicable procedure and standards.

1.1.     Where this specification and the petroleum refinery piping code ASME B31.3 conflict, this standard shall govern. Sound engineering practice shall be followed in the absence of specified standards or specification subject to OWNER prior approval. 

1.2.            CODES AND STANDARDS - Piping Fabrication and Erection

SpecificationStandards referred to in this specification shall be the latest editions, including all revisions and addenda as listed below:

Process Piping                                                                    ASME B31.3

Unified Inch Screw Threads                                           ASME B1.1

Pipe Threads, General Purpose (Inch)                               ASME B1.20.1

Pipe Flanges and Flanged Fittings NPS 1/2”                    ASME B16.5

Through NPS 24”

Factory-Made Wrought Steel Butt welding Fittings            ASME B16.9

Forged Steel Fittings, Socket Welding and Treaded            ASME B16.11

Butt Welding Ends                                                                    ASME B16.25

Square and Hex Nuts   (Inch Series)                                      ASME B18.2.2

Welded and seamless Wrought Steel Pipe                            ASME B36.10

Stainless Steel Pipe                                                              ASME B36.19

Wrought Stainless Steel Butt Welding Fittings                   MSS-SP-43

Boiler and Pressure Vessel Code                                               ASME-VIII

Boiler and Pressure Vessel Code                                                ASME-IX

piping fabrication specification


The following specifications are applied as supplement of this specification.

A.    Piping Material                                                              

B.    Construction Work for Piping                                                    

C.    Pressure Test of Piping System                                         

D.    Cleaning for Pipe Lines                                                    

E.    Welding Procedure for Piping                                           

F.    Welder Qualification Test                                                                   

G.    Inspection & Test of Piping Construction                             

H.    Piping hanging & support                                              

I.     Piping Design                                                                   

J.     Marking & Color Coding                                        

K.   Painting Specification  

2.                 DEFINITION

2.1.            DIVISION OF WORK

All piping will be fabricated by a field construction crew either in a pipespool fabrication shop hereinafter referred to as the "shop” (as per ------) or in‑place hereinafter called the "field".

2.2.            PIPE SPOOL DEFINITION - Piping Fabrication and Erection Specification

The word pipespool, as used in this specification, is a unit of prefabricated piping consisting of pipe, fittings, flanges, and other components integral to the assembly. This piping is assembled in the shop and conveyed to the construction site for installation. 

2.3.            PIPE SPOOL INDEX

All pipespools to be constructed by the fabricator are listed in the Pipespool Index.  Each index is in numerical order for each field assembly area.  The shop shall fabricate the pipespools in the order they are listed in the index, unless a list giving some other priority is provided by Consultant.

The index will show for each pipespool the pipespool number, quantity of identical  pipespools, revision mark, line number, material class, and special information or treatment. 

The assembly area, revision date, and material are given at the top of each sheet.  Included with each index for each area is a Pipespool Index Revision page.  This page is a record of all revisions to the pipespool index.  The shop shall fill out and keep current the information columns on the pipespool indexes, and provide copies to Consultant when requested or completed. 

3.                 DRAWING APPLICATION

3..1.            PIPESPOOL INDEX

All pipelines are identified with the line classification  on  the  plan and isometric drawing.

3.2.            EXTENT OF PIPESPOOLS

Where field installed material connects to shop  fabricated  pipespools, the  shop fabricated spool will include all branch connections for field piping, up to the first field butt weld, first  field socket weld, first screwed connection, or first flanged joint including the first flange.  Pipespools in all sizes of butt welded and socket welded construction will be prefabricated in the shop. 

Threaded piping and threaded components which are installed as attachments to shop fabricated pipespools shall be termed field installed materials.  Straight runs of piping indicated as random piping are not pipespools.  These straight runs are installed by the field crews in random lengths.  The division between the three different types is shown on the  drawings as indicated in figure.

Here, "S" means shop fabricated, "F" means field‑installed material and "R" stands for field‑installed random lengths.  "FW" is a weld done in the field. 

3.3.            ISOMETRIC DRAWINGS - Piping Fabrication and Erection Specification

Consultant will provide the isometric drawings for all 1-1/2 inch and larger for stainless steel and 2 inch and larger for carbon steel. The isometric drawing will show also combined line number, equipment nozzles to which the pipeline is connected, call outs and high point vents and low point drains. A bill of material take off for the isometric shall be attached.  The bill shall include the code, size, quantity and description for each piping component. 

3.4.            SYMBOLS

Drawing symbols used on the piping drawings are defined on legend.  The following  definitions specify what  is  required  when certain letter symbols are used on the drawings.

"FW"  A field weld is the joining of two components, beveled for welding, made to drawing dimensions, and to be welded at the construction site.

"FU"    A fit‑up weld is a field weld that allows some dimensional adjustment of a pipe spool during final assembly. One of the mating ends is square‑cut 3 inches longer than the dimensions required.  The other mating end is bevel‑cut to the exact dimension indicated on the drawings.

"DW"   A dummy weld is a weld connecting a supporting appurtenance to a pipeline.  The support is an extension of the piping but with no connection into the fluid stream. 

3.5.            FIELD WELDS

The Construction contractor shall locate on the piping erection drawings, field welds or fit‑up welds as required for site erection, except no location will be shown for socket weld connections between pipe spools built in the shop and those built at the construction site. 

3.6.            DIMENSIONS

Unless otherwise specify all dimensions terminating at a flange are measured from the gasket face for raised‑face flanges and flat‑face flanges, and the raised face of ring‑joint flanges. Gaskets are indicated by a short line placed beside or between the dimension limit lines. Only gaskets which  have a different thickness than the material class gasket are dimensioned.

Whenever an overall dimension does not appear on a drawing, the dimension is assumed to be the sum of individual standard fitting lengths coincident with the piping line class material. 

4.                 FABRICATION

4.1.            GENERAL - Piping Fabrication and Erection Specification

Fabrication works shall comply with the drawings and this specification including relevant Engineering and Construction Specifications.

4.1.1.    All weld numbers and welder’s identification number shall be painted close to the weld, to enable trace ability of each weld and each welder, socket welds shall be numbered per fitting, e.g. S.W tee has one weld number.

4.1.2.     Construction Contractor shall maintain the color coding on piping materials to allow easy and quick reference in accordance with the project engineering specification.

4.1.3.       All materials included in the finished piping systems shall be undamaged.

4.1.4.       Construction Contractor must provide adequate protection for piping, flange faces, threaded connections, etc. to prevent damage during handling and storage. Construction Contractor shall ensure that flange faces are protected from corrosion or rust.

4.1.5.      Piping shall be stored in a relatively clean, dry or well drained area on elevated dunnage and protected against contact with salts or salty water.

4.1.6.   All attachments to piping, i.e. saddles, pads, etc. are to be made of same material to the pipe.

4.2.            DIMENSIONAL - Piping Fabrication and Erection Specification


4.2.1.      Wrought Bends 

A.     Wrought bends shall show no significant marks or corrugations and shall be smooth and regular in outline.  Flattening shall not exceed 8% of the pipe outside diameter for pressure duties, or 3% of the pipe outside diameter for vacuum duties. There shall be no significant thinning when the pipe bend radius is 5 x nominal diameter or greater.

B.   In general thickness stainless steel pipe of equivalent to schedule 10S and thinner shall not be bent.

4.2.2.      Pipe Dimensions

Tolerances shall be ±1.5mm from flange face to flange face, or centerline of pipe to flange face.

4.2.3.      Flange Face

Flange faces shall not be concave.  Convexity from flange bore to joint face periphery shall not exceed 0.15mm per centimeter width of joint face.

4.2.4.      Squareness of Flanges

Flanges shall be square to the axis of the pipe to within an angle of 0° ‑ 18' (0.3°) I.E.  0.05mm per centimeter measured across the face of the flange, with the pipe adequately supported.

4.2.5.      Bolt Holes of Flanges

Flange bolt holes shall straddle the established centerlines (Horizontal or vertical). However, flanged connections on equipment may vary and should be individually checked.  When these connections differ, the bolt hole orientation shall be indicated on the isometric piping detail sheet. Holes in double flanged pipes shall be correctly aligned. 

4.3.            WELD DETAILS - Piping Fabrication and Erection Specification

4.3.1.       Butt Welds

The term "Butt‑Weld" refers to circumferential butt joints only. Special requirements may be imposed where longitudinal welds are to be made and these welds shall not be carried out before Consultant has approved the methods to be used.  Longitudinal and spiral welds existing in pipes as produced at the mill are outside the scope of this specification.

4.3.2.      Weld Preparation

Weld preparation shall be in accordance with the following:

A.   Preparation standard shall be applied to ASME B31.3 and the modifications to the standard contained within clause 5.3.6 of this specification.

B.  Ends shall be beveled or square cut for welding as follows:

1)  Beveled for wall thickness greater than 2.3mm

2)  Square cut for wall thickness 2.3 mm and less

4.3.3.      Root Gaps

Spacers shall be used while tack welding pipe and fittings in position to insure proper gap and full penetration in welding. The tack welds complying with the requirements of ASME B31.3, 328.5.1(C) may be allowed to become a part of the finished weld, whereas those not complying are not acceptable and must be chipped out before completing the weld.

4.3.4.      Bore Matching and Alignment

Bore matching and alignment shall be in accordance with ASME B31.3.  Where pipe, fittings and flanges are to be joined by circumferential butt‑welds, the corresponding parts shall be modeled and matched so that any misalignment at the inside of the piping shall not exceed 1/16 inch at any point of the circumference of the joint.

Fit‑up work may include pressing, hammering, local heating or grinding as required to reduce any misalignment due to diameter tolerances, out‑of‑roundness or unequal wall thickness of the parts of less than 1/16 inch. parts having unequal wall thickness and bores shall be prepared in accordance with one of the  details  shown  in  ASME  B31.3.

4.3.5.      Cutting

A.  Pipes may be cut mechanically by sawing or grinding machine.

B. Cutting method involving heating e.g. Flame or arc cutting for carbon steel are allowed providing the cut edge is machined or ground back sufficiently far to give specified parent material properties at the cut edge with a minimum of 1.5 mm.

C. Plasma‑jet cutting may be use to cut austenitic stainless steel pipes and other materials.

D.   Flame cutting of austenitic stainless steel pipe is not allowed.

E.   Other methods of cutting may be used providing written approval is obtained from Consultant.

4.3.6.      Welding Position of Longitudinal Seams

Longitudinal seams in seam welded pipe shall be located so as to clear openings and external attachments possible.  Longitudinal seams in adjoining courses shall be  preperably at 180°but a minimum between seams are in accordance with construction specification. 

4.4.            BRANCH WELDS - Piping Fabrication and Erection Specification

Branch connections shall be located as indicated on the piping detail sheet or isometric piping drawings. All branch connections shall be designed in accordance with Para. 304.3 of ASME B31.3.   Forged or extruded branch connections are preferred.

4.4.1.      No Fitting

Branches shall be of  'Stub‑in' design in accordance with Construction Specification 0000-S1830-003 and ASME B31.3.

4.4.2.   Forged branch attachments (Brancholets) shall be of the type specified on Consultant's drawings and fitted accurately to the contours of the run pipe.

4.4.3.      Reinforcing Pads

A.    For pressure reinforcement

Reinforcing pads required by the referenced code or by piping detail sheets shall be provided with at least one vent hole if fully welded. The hole shall be drilled and tapped with a 1/8 inch pipe thread for testing and venting. The tapped hole shall be plugged using wood, plastic or mastic material not capable of retaining pressure. 

B.    For structural attachment

Reinforcing pads for structural attachment shall be provided with an untapped hole of 1/4 inch (6 mm) diameter for venting.

C.  Where reinforcing pads are fitted either for branches or structural attachments they shall be  accurately shaped so that no gap larger than 1/8 inch (3.0mm), measured before welding, shall exist between the periphery of the pad and the pipe to which it fits.

4.4.4.      Mitered Bends

Mitered bends shall be in accordance with piping material specification ------. The number of cuts shall be as stated on the drawing.  Mitered bends are used only when specified on the drawings and shall be in accordance with ASME B31.3 Chapter V. A joint efficiency not exceeding 70% shall be used in the strength calculations for mitered bends. The welds in mitered bends shall penetrate the full thickness of the pipe and the bead on the inside of the throat shall be smooth and have an even curvature. In order to prevent a notch effect.

4.4.5.      Beveled Ends

Refer to Construction Specification XXX

4.4.6.      Fillet Welds

Refer to Construction Specification XXX

4.5.            BENDING - Piping Fabrication and Erection Specification

4.5.1. Bends shall conform dimensionally to the drawings and relevant clauses of this specification. Hot bend is not permitted.

4.5.2.      Cold Bending

A.  Cold bends to a centerline radius greater than five (5) times the nominal pipe diameter may be manufactured without a subsequent heat treatment unless a heat treatment is specified on the project specification, piping detail sheets, or isometric drawings.

B.    Cold bends to a radius less than five (5) times the nominal pipe diameter is not allowed.

C.   Bending after completion of fabrication to meet dimensional requirements shall not be carried out without the approval of the engineer.

5.                 WELDING - Piping Fabrication and Erection Specification

5.1.            WELDING PROCESS - Piping Fabrication and Erection Specification

5.1.1.     Basic welding requirements are to be in accordance with ASME B31.3.  Welders shall be approved in accordance with the relevant clauses of this standard.

5.1.2.  Welding shall be carried out by one, or a combination of  the  following processes:

A. Shield metal arc welding (SMAW)

B. Inert gas metal (MIG)

C. Tungsten inert gas with filler wire (TIG)

The (SMAW) and (TIG) processes are preferred as welding process.

5.1.3.   Backing rings shall not  be  used  without  prior  written  content  and approval of Consultant.

5.1.4.  Where tack welding is carried out, tacks shall be as large as possible and to the satisfaction of  the Consultant inspection. Tack welds shall be removed so that they do not form part of the finished weld unless they are produced fully qualified and tested welders to the same procedure as the finished weld, in which case they may be absorbed into the finished weld.

5.1.5.     Flange faces shall be kept free from weld spatter and arc strike. 

5.2.            WELDING PROCEDURE - Piping Fabrication and Erection Specification

5.2.1.     Welding procedures are to be qualified in accordance with the ASME boiler and pressure vessel code section IX and ASME B31.3, and shall be approved by Consultant before any work is carried out.

5.2.2.   Welder's competence shall be determined in accordance with Welder Qualification Test        

5.2.3.     It is fabricator's responsibility to reference each weld to  its  welder and correct procedure.

5.2.4.      Electrodes and filler wires shall conform to the requirements  specified in para. 7.1.

5.2.5.      Requirements for mixed metal welds are specified in para. 6.

5.2.6.   Fusion faces may be prepared by sawing, chipping, machining or grinding. They shall be smooth and free from defects and together with the adjacent material shall be thoroughly cleaned of oil, grease, paint and shall be free from all rust, scale, ice/water for a distance of 50 mm from the edge of the weld.

5.2.7.    The visible surface of all welds are to be clean of slag, regular uniform in contour, without undercuts, crack or blowholes and free from spatter.

5.2.8.  Weld reinforcement: The thickness of weld reinforcement shall not exceed the following, considering the thinner component being joined:

Component Thickness  (in.)               Maximum Reinforcement (in.)

1/2 and Under                                                  1/8

from 1/2 to 1                                                    5/32

Over 1                                                               3/16

For double welded joints this limitation on reinforcement shall apply separately to the weld reinforcement inside and outside.  The finished internal and external surfaces of the weld shall merge smoothly into the component surfaces or the weld toe.

5.2.9.    When unacceptable defects are found in complete welds, they are to be removed by grinding, chipping or machining.

5.2.10.   The basic principles of the welding procedure initially used are to be employed for repair of faulty welds. 

5.3.            SPECIAL PROCESS CONTROL - Piping Fabrication and Erection Specification

5.3.1.    Work control procedure shall be prepared prior to start the special process such as heat treatment.  Processing and result of special process shall be recorded and maintained to verify the work quality.

5.3.2.   Heat Treatment of flame‑cut edges for carbon steel is not required when the edges are dressed  back in accordance with para. 4.3.5. B where dressing back proves to be impossible, then such undressed or partly dressed edges shall be stress relieved before welding.

5.3.3.       Preheating - Piping Fabrication and Erection Specification

A.    When the welding procedure does not include pre‑heating and the ambient conditions  are such that the metal temperature of the parts to be welded are below 4°C, the surface in a  zone extending 15 mm each side of  the joint is  to  be  heated to  20°C "Handwarm" before welding commences.

B.   Preheating shall be carried out in accordance with ASME B31.3 unless para. 5.3.4. A applies.

C.  In addition to the requirements of ASME B31.3, when rutile and cellulosic electrodes are used, then preheat shall be applied on wall thicknesses of 20 mm (3/4") and above.

5.3.4.      Normalizing

Normalizing shall be carried out as follows:

Temperature                                      920°C/950°C

Time/Inch of Thickness                       1 Hour

Minimum soaking time                         1/2 Hour

Cooling shall be uniform at a rate less than 250°Cper hour down to 300°C, thereafter cool in still air.

5.3.5.      Stress Relieving - Piping Fabrication and Erection Specification

A.     Irrespective of pipe wall thickness, PWHT shall be performed on all type joints butt, socket, etc, for piping classes A2T3MR, AUT3P, B2T3MR, B2T6MR, D2T3MR, A2D2, B2D2V, BCDX, D2D2V, for other piping classes PWHT shall be carried out in accordance with ASME B31.3.

B.     After completion of final P.W.H.T. hardness test shall be performed in accordance with ASME B31.3. One test is required in the weld and one test is required in the heat affected zone (HAZ). 

C.  Welds produced in austenitic stainless steel shall not require stress relief, unless this is specifically called for in the drawings or pipeline specifications.

5.3.6.      Temperature Measurement

Temperature measurement shall be in accordance with ASME B31.3.

5.3.7.      A record of the time/temperature for normalising and stress relief  must be kept. 

6.                 MIXED METAL WELDS - Piping Fabrication and Erection Specification

6.1.           CARBON AND AUSTENITIC STAINLESS STEELS - Piping Fabrication and Erection Specification

6.1.1.    Where welds are to be produced between carbon steels and austenitic stainless steels, the weld procedures, welding techniques etc., shall be those appropriate to the austenitic stainless steel.

6.1.2.   Electrodes and filler wire shall be ER 309, E309, or ER NiCr3, ENiCr Fe3 the choice depending on service conditions. Any heat treatment required shall be that appropriate to the grade and thickness of carbon steel involved. The welding procedure proposed shall be approved in writing by Consultant. 


6.2.1.   Where welds are to be produced between low alloy steels and carbon steels, the above procedures, electrodes, filler wires, welding technique and heat treatment etc., shall be appropriate to the grade and thickness of the low alloy steel involved. Electrodes must be of the basic type. 

6.3.      DIFFERENT GRADES OF AUSTENITIC STAINLESS STEELS - Piping Fabrication and Erection Specification

Where welds are to be produced between differing grades of stainless steels, the weld procedures, electrodes, filler wires, welding techniques, etc., shall be those required by the higher grade of material. 

6.4.   LOW ALLOY (CHROMIUM MOLYBDENUM ETC.) AND AUSTENITIC STAINLESS STEEL - Piping Fabrication and Erection Specification

6.4.1.  Where welds are to be produced between low alloy steels and austenitic stainless steels, the weld procedures, welding techniques, etc., shall be those appropriate to the austenitic stainless steel.

6.4.2.       Electrodes and filler wires shall in general be of higher alloy content than the austenitic stainless steel.  Any heat treatment required shall be that appropriate to the grade and thickness of low alloy steel involved. 

7.                 MATERIALS - Piping Fabrication and Erection Specification


7.1.1.      For Carbon Steel Pipes

A.   All electrode and filler wires shall comply with AWS A5.1, AWS A5.2 and AWS A5.18.

B.   Electrodes to be used for general butt welding of low carbon steel pipes will be as follows:

1)  Pipe wall thickness up to 19 mm  (0.75")  use  cellulosic electrodes E6010 and E7018.

2)  Pipe wall thickness 19mm (0.75") and above and special carbon steel (for low  temperature  or  high  carbon  content), ER70S-3 & basic electrodes E7018.

7.1.2.    For Austenitic Stainless Steel Pipes

A.    All electrode and filler wires shall comply with AWS A5.4 and AWS A5.9.

B.    Electrodes to be used for general butt welding of austenitic stainless steel will be rutile type EXXX‑16.

7.1.3.    For Alloy Steel Pipes

A.       All electrode and filler wires shall comply with AWS A5.4 and AWS A5.5.

B.  Welding electrodes to be used for general butt welding of alloy steel piping shall be as follows:

PIPE ELECTRODE ASTM SPECIFICATION A335 AWS-ASTM CLASSIFICATION   Grade P9, 9%Cr-1% Mo Grade P7, 7%Cr-1/2% Mo Grade P5, 5%Cr-1/2% Mo Grade P22, 2-1/4%Cr-1% Mo Grade P11, 1-1/4%Cr-1/2% Mo Grade P12, 1%Cr-2% Mo   E 505-15 E 7Cr-15 E 502-15 E9018-B3 E8018-B2 E8018-B2 

7.1.4.   For Carbon‑Molybdenum Alloy‑Steel Pipes

A.    All electrode and filler wires shall comply with AWS A5.5.

B.    Welding electrode shall be 7018 A1.

7.1.5.     Welding Dissimilar Metals

A.  The dissimilar metal welds should be avoided whenever possible, using instead some mechanical joint such as a thread or flanged connection.

B.   There are innumerable combination of dissimilar alloys which could be jointed, and most of these combinations are special cases which must be handled on an individual  basis,  with  the  welding  procedure depending on the intended use.

C.   The composition of the joining metal must be compatible with both alloys, or a buffer layer must be placed between them.

D.  If high temperatures are involved, particularly if cycle, the coefficients of thermal expansion of the parent metals and diluted weld metal must be considered.

E.   If hardenable alloys are involved, consideration must be given to eliminating hard  areas and brittle areas, or to restoring strength, hardness and toughness, depending  on  whether  or  not  the  design requires a high strength member.

F.   If corrosion is involved, galvanic attack and resistance to process corrodents must be taken into account.

G.  Mechanical, formability and other fabrication operations may require special consideration.

H.     Welding electrodes shall be in accordance with Specification XXX.

7.1.6.     The particular brands of electrodes and wires chosen shall be approved in writing by the engineer before use.

7.1.7. Storage of electrodes and other welding materials shall be in accordance with the vendor's instructions.

7.1.8. Refer to following specification for complete list of electrodes and filler materials. 

7.2.     GRINDING WHEELS - Piping Fabrication and Erection Specification

7.2.1. For Austenitic Stainless Steel Pipes

A.  Grinding shall be carried out using resin bonded alumina or silicon carbide grinding wheels.  Rubber bonded wheels or wheels containing sulphur shall not be used.

A.       Wheels previously used on ferritic steels shall not be  used  on  the carbon steels. 

7.3.    WIRE BRUSHES - Piping Fabrication and Erection Specification

All wire brushes used on austenitic stainless steel pipes  shall  be  of stainless steel. 

8.         INSPECTION AND TEST - Piping Fabrication and Erection Specification

Inspection shall be in accordance with ASME B31.3 and the following inspection requirements.

8.1.            PROCEDURE AND RECORD - Piping Fabrication and Erection Specification

8.1.1.   Inspection and test procedure/plan shall be prepared and approved prior to inspection activity.

8.1.2.     Result of inspection and test shall be recorded and maintained to verify the quality of items and activities. 

8.2.            RADIOGRAPHY

Radiography shall be applied in accordance with  Inspection & Test of Piping Construction 

8.3.            VISUAL EXAMINATION

Visual examination shall be carried out in accordance with Inspection & Test of Piping Construction

8.4.            PRESSURE TEST

8.4.1. Pressure testing shall be carried out in accordance with ASME B31.3 and Pressure Test of Piping System

8.4.2.      Extent of pressure testing shall be indicated on the line list.

8.4.3.   Pressure testing shall be hydrostatic unless otherwise stated.

8.4.4.   Shop testing of  finished  fabricated  piping  is  not  required  unless specified.

8.4.5.   Where site hydraulic testing is to be avoided, all shop fabricated piping, including make‑up lengths and lengths with loose flanges, shall be shop tested hydraulically.  Provision shall be made by the fabricator for closing the open ends of pipe for this test.  Where this procedure is  required,  it  will  be specified on  the  drawings and  pipeline specifications.

8.4.6. All pressure testing shall be carried out after the application of any specified heat treatment.

8.4.7.  For austenitic stainless steel pipelines, hydrostatic tests shall be carried out using clean water unless other fluids are specified on the drawings or pipeline specifications. Particular attention must be paid to using potable water. Chlorine content of less than 50 PPM should be used wherever possible, water having a chlorine content above 100 ppm should not be used in any circumstances, and where it is necessary to use water within a range of 50‑100 ppm, lines shall be flushed with a chlorine‑free liquid with a short period of testing. 

9.      CLEANING - Piping Fabrication and Erection Specification

9.1 All bores of all fabricated piping shall be free from all sand, scale, weld spatter etc. refer also to para. 5.2.7 and 5.2.8.

9.2.    If special cleaning is required, this will be the subject of  a  special specification.

9.3. The cleaning of austenitic stainless steel pipe surfaces prior to welding shall not involve the use of hydrochloric acid, chlorine compounds, or water with a chloride content in excess of 50 ppm. 


10.1.        DRAINING OF BORES - After hydrostatic testing and cleaning, where specified, the bores of pipes shall be thoroughly drained and the ends immediately sealed in accordance with para. 10.2. 

10.2.        PROTECTION - Piping Fabrication and Erection Specification

10.2.1.  Pipe‑ends and flange faces shall be properly protected against the ingress of dirt, mechanical damage and atmospheric corrosion.  The term "pipe‑end" shall include any weld preparation.  The  protection applied shall not be capable of passing into the bore of the pipe.

10.2.2. Threaded connections shall be fitted with a line class plug  or  covered with a plastic sheet securely wired or taped to the spool.

10.2.3.   Socket weld connections shall be fitted with taped polyethylene plugs or plastic sheet securely wired or taped to the spool. 

11.            ERECTION - Piping Fabrication and Erection Specification

11.1.        VALVES

Valves equipped with chain wheels shall have the stems arranged so that chains do not fall on equipment.  Hooks shall be provided to hold chains clear of operating areas.  Chain wheels will be shown on the piping drawings.  Install valves so that the stems are not below a horizontal position.  Orient all valves so that the hand wheels do not obstruct passageways. 

11.2.        FLANGED JOINTS - Piping Fabrication and Erection Specification

Protect all flange faces from damage. Take care not to mar the faces of the flanges.  Bring all flanged joints up flush so that the entire flange face bears uniformly on the gasket, and then take up with uniform bolt  tension.  In bolting joints with spiral wound gaskets, the gasket shall be compressed until the raised faces of the flanges uniformly contact the compression gauge ring. 


A flange cover shall be kept on all flanged connections to pumps, compressors, turbines, and similar equipment until ready to connect the piping. Piping connecting to mechanical equipment, such as pumps, turbines, and compressors shall be fitted‑up  in close parallel and lateral alignment, prior to tightening the bolting or welding the joints.  The installation shall be approved by the inspector prior to tightening the bolting.  Carbon steel piping that has not required post‑weld heat treatment may be heated for minor corrections in fit.  The temperature shall not exceed 660℃ Cooling of the pipe shall not be accelerated by the application of water. The inspector shall be notified when heating for fit‑up is required. 

11.4.        RESTRICTIONS - Piping Fabrication and Erection Specification

All restrictions which would interfere with filling, venting, draining, or flushing shall not be installed until after completion of the pressure test and line flushing operations.  This includes orifice plates, flow nozzles, venturis, rotameters, PD meters, turbine meters, magnetic meters, strainer screens, and similar in‑the‑line equipment. 

11.5.        TEMPORARY GASKETS - Piping Fabrication and Erection Specification

Protect gaskets from damage until final installation is complete. When temporary make up at flanged joints is required in piping systems using special gaskets, make up the joint with a less expensive sheet  gasket and save the special gasket for the final installation. 

11.6.        PIPE SUPPORTS - Piping Fabrication and Erection Specification

All field supports shall be installed in accordance with the standard drawings.  If the field supports are not installed or are unavailable when the piping is erected, use temporary blocking or other adequate means of support until the field supports can be installed.  Careful consideration must be given to the support of 2‑inch and smaller piping to prevent excessive deflection. 

11.7.        EXPANSION JOINTS - Piping Fabrication and Erection Specification

Check the expansion joint specification for special instructions.  Corrugated expansion joints shall be installed with length extended or compressed for the ambient temperature condition at erection, depending on anticipated direction and magnitude of movement after the line reaches the operating temperature.  Make a final check to see that shipping ties have been removed after line tests and that any preset that may be specified has been accounted for.

11.8.        TEMPORARY STRAINERS - Piping Fabrication and Erection Specification

Temporary suction strainers shall be installed at the suction nozzles of all pumps and  compressors before pipeline flushing.  They shall be located between the suction block valve and the equipment. 

11.9.        SPRING HANGERS - Piping Fabrication and Erection Specification

The variable and constant support type spring hangers are preset, for the cold condition, in the factory.  The gags and shipping spacers should be removed until after hydrostatic testing of the line has been completed.

Any dimensional adjustments that have to be made to the load flange on the compression‑type springs, or to the rod assembly on suspended‑type springs, should be made before the gags are removed.  Once the spring is unblocked it is very difficult to make any adjustments. 

11.10.    PLATFORM HOLES - Piping Fabrication and Erection Specification

Platform holes for piping have been sized for pipe or insulation outside diameter plus approximately 25mm clearance. Field welds are necessary for the installation of flanged pipespools unless the platform supports are intended to be clear of piping, the field shall add or relocate any structural supports and stiffeners required because of holes made for piping. 

11.11.    THREADED CONNECTIONS - Piping Fabrication and Erection Specification

All pipe threads shall be taper‑pipe threads in accordance with ASME B1.20.1 without exception.  Teflon tape shall be used for all threaded joints where the design temperature in 205°C or below.



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