Quy trình chế tạo và lắp đặt đường ống (Piping Fabrication & Erection Procedure)

Piping Fabrication & Erection Procedure


__________

TABLE OF CONTENTS
1.

PURPOSE...........................................................................................................................................4

2.

REFERENCE DOCUMENT...................................................................................................................4

3.

ABBREVIATIONS................................................................................................................................5

4.

FABRICATION PROCEDURE FOR PIPING............................................................................................6
4.1. Scope.......................................................................................................................................6
4.2. Fabrication area......................................................................................................................6
4.3. Material control......................................................................................................................6
4.4. Fabrication sequence.............................................................................................................7
4.4.1.
Spool fabrication flow chart...................................................................................7
4.4.2.
Marking...................................................................................................................8
4.4.2.1 Marking during pre-fabrication..........................................................................8
4.4.2.2 Marking spool pieces for installation..................................................................8

4.4.3.
Cutting and Edge preparation................................................................................9
4.4.4.
Edge Preparation for Welding................................................................................9
4.4.5.
Fit – up..................................................................................................................10
4.4.6.
Welding.................................................................................................................11
4.4.6.1 General.............................................................................................................11
4.4.6.2 Branch connections and outlets........................................................................14
4.4.6.3 Storage and issue of consumables....................................................................15
4.4.6.4 Qualification of welders and welding operators...............................................15
4.4.6.5 Tack Welds........................................................................................................15
4.4.6.6 Temporary Attachments....................................................................................16
4.4.6.7 Threaded and Socket Welds..............................................................................16
4.4.6.8 Material Segregation........................................................................................16
4.4.6.9 Tolerance..........................................................................................................17
4.4.6.10 NDE and repair of defect...................................................................................17
4.4.6.11 Protection and storage of pipe material...........................................................17
4.4.6.12 Painting.............................................................................................................18
4.5. Installation............................................................................................................................19
4.5.1.
Pipe work erection...............................................................................................19
4.5.2.
Flange joints..........................................................................................................20
4.5.3.
Equipment flange connection..............................................................................20
4.5.4.
Gaskets..................................................................................................................20
4.5.5.

Pipe support.........................................................................................................21
4.6. Testing...................................................................................................................................21
4.6.1.
General.................................................................................................................21
4.6.2.
Material, equipment & test medium...................................................................22
4.6.3.
Pressure testing....................................................................................................22
4.6.4.
Ddrying after test..................................................................................................22
All piping shall be completely drained of all testing fluid...................................................22

5.

REPORTING.....................................................................................................................................22
Page 2 of 21


__________

PURPOSE
This procedure describes the general requirements for shop and field fabrication, installation and
inspection of all piping materials (except GRE) for the MM1 & MM2 modules of Ghana FPSO Project. All
non-metallic Pipes shall be fabricated in accordance with the manufacturer’s recommendations, and
Project specifications.
In addition to the information contained in this procedure, constructor will carry out fabrication and
installation work to meet the requirements of drawings, technical specification, standards and codes.

1.

REFERENCE DOCUMENT
Company General Specifications:
DESCRIPTION
TITLE
1305-GS-L-FD-00002
Piping Design Criteria
20367.PIP.MEC.SDS
Piping material classes
05892.PIP.MEC.SDS
Piping and Piping Components for Plants
15801.PIP.MEC.SDS
Specification – Manual Valves
Specification - Pipes and Piping Components for Plant Piping Project
06732.PIP.MEC.SDS
Specifications
20368.PIP.MEC.FUN
Functional Specification - Carbon Steel Piping Welding
Functional Specification – Piping Weld Examination General
20377.PIP.MEC.FUN
Requirements
1305-GS-R-SA-00004
Pressure Vessels Specification
1305-GS-R-SA-00011
Pig Launchers and Pig Receivers Specification
Equipment and Materials Preservation (Shipping and Preparation for
1305-GS-M-SA-00002
Storage) Specification
1_3_3_20
Minimum Safety Standards
1305-YP-00-Z-SA-00004

General Technical Requirements
1305-GS-Q-LA-00002
pipe support specification
1305-YP-98-J-SA-00002
Paint specification
PROJECT Documents:
DESCRIPTION
1305-XXXX-00-A-TA-00001
1305-XXXX-00-X-TA-00001
1305-XXXX-00-X-KA-00005
1305-XXXX-00-X-KA-00006
1305-XXXX-00-X-KA-00010
1305-XXXX-00-X-KA-00003
1305-XXXX-00-Q-TA-00004
1305-XXXX-00-Q-KA-00010
1305-XXXX-00-Q-KA-00018
1305-XXXX-00-Q-KA-00009
1305-XXXX-00-Q-KA-00020
1305-XXXX-00-A-KA-20003

Project Execution plan
Project HSE Plan
Permit To Work Procedure
Site Entry Procedure
Inspection and Maintenance of Lifting Equipment Procedure
Radiation Safety Procedure
Inspection & Test Plan for Piping Fabrication
Welding Control Procedure
Dimensional Control Procedure
Welding Consumable Control Procedure

Welding Procedure Specification for Piping
Material Control Procedure

Standards:
DESCRIPTION
ASME B31.3 - 2012

Process Piping

TITLE

TITLE

Page 3 of 21


__________

DESCRIPTION
ASME B16.25 - 2012
ASME B1.20.1 - 2013
ASME Section V - 2013
ASME Section VIII - 2013
ASME Section IX - 2013
ASME B16.5
ASME B16.2

2.

TITLE

Butt Welding Ends
Pipe Threads, General Purpose
Non-Destructive Examination
Pressure Vessel (Where applicable)
Welding and Brazing Qualification
Pipe flange and flanged fitting
stainless steel spiral wound gasket

ABBREVIATIONS
WORD
CLIENT
COMPANY
CONTRACTOR
FPSO
DNV GL
ANSI
API
ASME
ASTM
ISO
P&ID
PMT
PPE
QA/QC
DSS
SS
CS
CUNI
GRE
NDT

RT
PT
MT
ACC
REJ
WPS
PMI
OS&D

3.

DEFINITION
ENI GHANA E&P Ltd
Yinson Production Pte Ltd
XXXX Mechanical and Construction (XXXX M&C)
Floating Production Storage and Offloading (vessel)
Det Norske Veritas Germanischer Lloyd
American National Standards Institute
American Petroleum Institute
American Society of Mechanical Engineers
American Society for Testing and Materials
International Standards Organization
Process and Instrumentation Diagram
Project Management Team
Personnel Protective Equipment
Quality Assurance/Quality Control
Duplex Stainless Steel
Stainless Steel
Carbon Steel
Copper Nickel

Glass Reinforced Epoxy
Non-Destructive Testing
Radiography Testing
Dye Penetrant Testing
Magnetic Paricle Testing
Accepted
Rejected
Welding Procedure Specification
Positive Material Identification
Over short & damage

FABRICATION PROCEDURE FOR PIPING
3.1. Scope
This procedure serves as a guideline for fabrication and erection piping work. The procedure applies
to all piping fabrication, including piping within packaged units or other sub-assemblies. It does not
apply to instrumentation piping downstream of the first block valve on a pipe header.

Page 4 of 21


__________

3.2. Fabrication area
Fabrication of the different materials eg, carbon steel (CS), stainless steel (SS), Copper nickel (CuNi),
GRE and duplex stainless steel (DSS) materials will be carried out in separate designated areas.
Fabrication of SS, CuNi, and DSS shall far away/have separate workshop from CS material.
DSS, stainless steel and high alloy materials will be fabricated on the rubber sheet which is placed
on the table 1.5 meter higher than the ground. Hard segregation wall will be erected to separate
DSS, stainless steel and high alloy materials fabrication area with ferrous materials, eg…, carbon
steel grinding particles are eliminated in the DSS and stainless steel workshop.

DSS, stainless steel and high alloy materials will be stored in separate areas on the timber lined floor
of the stock area and will be moved by using of web slings or by hand into clean timber/ rubber
lined trestles/ work benches. There shall be no direct contact between carbon steel and DSS,
stainless steel or non ferrous material under any circumstances.
CS fabrication shall be carried out in the separate workshop. There shall be no direct contact
between CS to ground and other materials. CS materials, spools shall be supported on the bench,
stand pipe or wooden pallet. All tools, and consumable such as cutting machines, cutting & grinding
disc, measurement tools, wire brush… used for CS fabrication shall be suitable and identified by
color code.

3.3. Material control
All materials shall be fully inspected upon receipt to be ensured that the correct grade of material
has been supplied and that identification, dimensions, material quality and preparation are in
accordance with the requisite standards and specifications.
Material found to be defective or incorrectly marked shall be immediately placed in a quarantine
area separate from accepted material with sufficient safeguards to preclude it being used and
should be marked with QA “HOLD” label.
All flange faces including gasket grooves in ring joint flanges shall be protected by plastic cap,
plywood or equivalent method full time during fabrication.
Materials which have been damaged or found to have defects will not be used for fabrication. If
materials require to be repaired or accepted the decision shall be made by COMPANY. Before a
repaired is made, it must be subbmited to COMPANY for appvoral. Non-repairable material shall be
replaced.
Radial grooves or scratches on gasket faces are not allowed. Re-facing/ machining by the lathe shall
be required COMPANY

approval before perform. Any re-facing that reduces the raised face

thickness to less than the minimum thickness required in the relevant code or specification shall be

Page 5 of 21


__________

rejected. Thickness of raised face of flange will be checked after re-facing. Repair of defect shall only
be permitted if performed fully in accordance with the reference Code and standard.
OS&D report is required as per Material Control Procedure when material found to be defective or
incorrect.

3.4. Fabrication sequence
3.4.1.

Spool fabrication flow chart

The

spool

fabrication will be implemented with the sequence of marking, cutting, fit-up, Welding, NDT and
painting before erection on topside as flow chart below.
All NDT required for each piping spool shall be completed and accepted before any painting
application.

Page 6 of 21


__________

3.4.2.

4.4.2.1

Marking
Marking during pre-fabrication

All materials shall be marked for identification and traceability purposes as follow:

ITEM TO BE
MARKED

MARKING
FREQUENCE

MARKING
METHOD

Supplied Pipe

Off Cut Piece

Pen Marking

MARKING
CONTENTS
- HEAT No
- Material grade
- Drawing/Joint No

Shop welds on
Pipe Spool

Each Weld

Pipe Spool

Each

Components

Component

Pen Marking

- Welder ID/ Welding
Procedure

Pen Marking

- HEAT No
- Material grade

Marking pens shall be free from copper, zinc and chlorides for duplex stainless steels.
Items marked to facilitate traceability shall be maintained the marking throughout manufacturing
and fabrication stages. The marking which will be covered in the final assembly and coating shall be
transferred to the as-built traceability quality records. Traceability quality records shall be subjected
to COMPANY for verification.

4.4.2.2

Marking spool pieces for installation

All spools and field weld joints shall be marking with some information as the table below:
ITEM TO BE
MARKED
Field welds on
Pipe Spool
Completed
Pipe Spool

MARKING
FREQUENCE
Each Weld

MARKING
METHOD
Pen Marking

MARKING
CONTENTS
- Allocated Joint No
- Welder ID/ Welding
Procedure
- Isometric Number

Each Spool

Tagging

- Spool Number
- Deck Location

Tags shall be made of stainless steel plates and hang on the spools by stainless steel wire during
fabrication and installation.

3.4.3.

Cutting and Edge preparation

Carbon steel shall be cut by methodology of gas cutting guide touches, cutting discs machines or
mechanical cutting machines.

Page 7 of 21


__________

For Stainless steel and DSS, the bevels shall be prepared by machining but a preparation by
automatic plasma cutting. The heat affected zone shall then be removed by grinding.
CuNi material shall be cut and beveled using mechanical sawing, using free silicon lubricant.
Carbon arc gauging shall not be used for cutting. Mechanically guided plasma cutting tools shall be
compatible materials for stainless steel, DSS to avoid any contamination. Cutting discs used for
cutting DSS shall be used exclusively for that purpose. If plasma arc cutting is used, the inside
surface of pipe must be thoroughly cleaned of all spatter.
Sufficient metal shall be removed in the beveling process to remove any heat affected zone (HAZ)
that occurred as a result of plasma arc cutting.
Wire brushes with stainless steel bristles will be used, dedicated to DSS, stainless steel and high
alloy materials. The files which to be used on stainless steels, DSS and non ferrous alloys shall be
compatible materials and dedicated to a particular alloy only.
All edges shall be accurately maintained as per design requirement with a smooth even surface with
all slag removed.

Beveling will be performed with a beveling machine or grinding. Separated machines or compatible
bevelling bits will be used for carbon steel and DSS, stainless steel. Preparation will be in accordance
with the approved WPS.
Galvanised piping shall be cut by using drop saw or mechanical cutting machine. Gas cutting is
prohibited. Threading shall be carried out after bending, forging or heat treatment. Screwed threads
shall be clean with no burrs, no slag, no tripping. Ends shall be reamed to remove burrs and
protected before assemble.

3.4.4.

Edge Preparation for Welding

The preparation of the edge for welding shall be done by machining or grinding with smooth
surface.
The surface of the edge prepared shall be free from tears, grease, oil slag, scale or internal burrs.
Stainless steel and high alloy pipe shall be beveled by a grinding or beveling machine. Machine
separated is used for carbon steel and DSS, stainless steel.
Any small burrs, nicks, paint, rust, oxide... or other irregularities on the weld bevel surface which
could be detrimetal to the weld shall be removed by flame, solvents, brush or grinding, for a lenghth
of 25mm across the bevel.
For weld performence with GTAW process, the cleaning shall be extended for 10mm from the edge
on the internal pipe surface by grinding.

Page 8 of 21


__________

Edge preparation shall be performed in accordance with the approved WPS and requirement in
20368.PIP.MEC.FUN_1_Functional Specification-Piping Carbon Steel Welding. Refer to section 2.1

3.4.5.

Fit – up

Alignment for the fit-up of the piping components shall be executed on a steel floor or steel jack
stand for carbon steel spools. For DSS, stainless steel and high alloy spool fabrication, the bench will
be covered with wooden planks or rubber. All stand pipes will be insulated with clean rubber
sheeting to prevent contamination of the spools.
Pipe shall be properly supported at least 1 meter higher the ground and aligned by jigs or clamps in
order to eliminate strains prior to tack welding. Where jigs or clamps are used for stainless steel and
high alloy fabrication, these items will be compatible or isolated to eliminate the possibility of
contamination with DSS, stainless steel and high alloy steel...
If necessary temporary supports shall be adopted to avoid the raise of stresses/deformations due to
the weight of pipes during assembling.
Hot or cold adjustment of spool (e.g by heat straightening) are not allowed.
The number of welds in a spool shall be kept to a minimum. Distance between two butt welds shall
not be less than one pipe diameter or 50mm whichever is smaller unless otherwise indicated in the
drawing or approved by COMPANY.
Attachment non-pressure parts by welds which cross with existing main welds should be avoided.
In case of use of longitudinally welded pipe, holes, opening, weldments along the longitudinal welds
are not allow.
During piping assembly the minimum distance between two longitudinal welds of two adjacent
pipes shall be twice the thickness with a minimum distance of 20mm.
The internal radial misalignment for bore up to 100 mm should not exceed 1.5 mm. If exceeded, it
shall be taper-trimed, machining may be conducted to improve root alignment with steeper angle ≤
300. Thickness after tapering shall not be lower than minimum design thickness. Hammering,
jacking or heating the pipe is not permitted.
The bolt holes of flanges shall straddle the normal horizontal and vertical centerline of pipe.
Holes for attachment of weldolets and nippolets shall be made by using drills for diameter less than

or equal 2 inches. For olet with diameter larger than 2 inches, the gas cutting torch to be used to
make wider holes. All slag, burrs shall be removed.
Components end (bevels, threads, flange faces, etc) shall be covered with proper means (plugs,
packages,..) during all transportation, storage, assembling stages. These coverings shall be removed
just before welding of these components.
Page 9 of 21


__________

3.4.6.
4.4.6.1

Welding
General

For Carbon steel and other materials, general welding requirements below shall be followed:
All welds shall be performed in accordance with the approved WPS which shall be displayed on a
notice board close to the work.
The beveled ends shall conform to the ANSI, B31.3 and approved WPS.
All edges of surfaces to be welded shall be cleaned to a bright metal finish, in a manner suitable to
remove any oxides, scale, grease, oil, or contamination due to flame cutting or machining. Oil paint
and dirt shall be removed from the pipe surface at least 25mm on both sides of the welds.
For at least one (1) inches from the bevel before welding is started, cleaning must be carried out just
prior to tacking and repeated just prior to welding.
No sealing or back-up rings shall be used.
Any cracks, blowholes, cold laps, unusual irregularities, slag, flux, or other impurities that appear on
the surface of any welding bead shall be removed by grinding or chipping before depositing the next
successive bead.
The requirement of the finished weld reinforcement for all materials shall comply with ASME B 31.3

specification for piping.
Two welders may be required on pipe Ф400mm and above. And pipe shall be marked with welder’s
identification number for area welded.
If arc strike occurs, this shall be removed by grinding followed by MT or Dye penetration test. For
new piping, the acceptable wall thickness is calculated inclusive manufacturing tolerances, corrosion
and erosion allowances. The part damaged of the pipe shall be removed.
Stainless steel wire brushes shall be used for all other materials except carbon steel and low alloy
steel.
Welding parameters shall be monitored and recorded by using measuring equipment with valid
calibration.
For DSS & Stainless steel, welding requirements below shall be followed:
Internal purge of argon shall be used for the GTAW process of first of four passes or a minimum of 5
mm of deposited weld metal on DSS and stainless steels as specified by WPS. Purging will be carried
out by using the best method for the particular application during welding.
Each end of the pipe adjacent to the weld of tie in spools shall be dammed by using water soluble
paper at a distance of 150 mm from the weld prep. Prior to the commencement of welding DSS, the

Page 10 of 21


__________

weld preparation area and filler metals shall be cleaned with acetone and clean rags without
excessive rubbing of the surface. Physical touching of the weld preparation area without clean
gloves is prohibited.
The sketch next sheet demonstrates :

All backing gas to be used during DSS welding shall be 99.99% argon. Gas shielding shall be
maintained until completion the first of four passes or a minium 5mm of deposite base material.
Oxygen level in the backing gas protection shall be less than 500ppm.

Anything which results in the weld metal being overheated or heated prolonged periods, welder
pausing or weaving, slow welding speed, welding without continuos filler addition, excessive slope
up/downtime for craters elimination, excessive inter pass temperature, will affect and reduce
corrosion properties and shall avoid.
All packages for filler material shall be marked by the producer/vendor with same reference number
indicated in the certificate. The oxidized end of partly used filler wire shall be snipped off prior to reuse.
Electrode and wire shall be identified by a color.
Electrodes shall be perfectly dried before use. They shall be properly stored, and dried in the ovens
with proper temperature control as welding consumable control procedure or manufacture’s
instructions.
Electrode and wire polluted by oil, grease, paint shall not be used. Electrodes damaged or exposed
to rain shall not be used also and they shall be destroyed.
Stringer beads with maximum width is three times the core diameter, shall be used.
Tack welds shall be done with qualified procedure and qualified welder.
Page 11 of 21


__________

The interpass temperature shall be monitoring to confirm compliance with the limit established by
the PQR/WPS.
A dedicated experienced DSS Welding Inspector shall be assigned to monitor during fabrication and
welding of duplex stainless steel material.
All paint markers to be used for DSS for identifying the weld joins and line number etc. shall be free
of sulfur content.
The use of a mechanical brush for cleaning weldments of DSS is not permitted. The use of pickling
paste is preferred.
Undercut or overlapping (cold lap) defects is not permitted.
Ambient

condition

for

welding

shall

be

conducted

as

requirements

in

the

20368.PIP.MEC.FUN_1_Functional Specification - Carbon Steel Piping Welding, section 3.5
Preheating and inter pass shall be maintained as per approved WPS
Peening and hammering of weld runs are prohibited.
The ferrite content measurement for completed welds to be conducted for DSS.
The welding area shall be kept clean, dry and draught free and shall be totally enclosed prior to
welding. Special care shall be taken to remove welding fumes from welding area.
The tungsten argon arc welding (GTAW) process shall be use for CuNi.
Metallic work benches shall be coverd by rubber, working area shall be suitably equipped in order to
prevent any contact between CuNi material and ferrous material.
All pipe is to be clear back for a distance of 100 to 150mm from the edge of each butt joint both

externally and internally. Stainless steel wire brushed shall be used.
Filler wire for welding shall be cleaned with stainless steel wool before use.
All tool, equipment to be used for CuNi material shall be separated with other materials. Wheel or
grinding discs shall be iron-free and shall not be organic-resin bonded.
Prior welding the joint surfaces and adjacent material of the joints shall be scratch to bright clean
metal using a stainless steel.
Autogenous welding is not permitted.

4.4.6.2

Branch connections and outlets.

Welded branch connections shall be jointed to the header with full penetration welds.
The bevel portion of the fitting marked by the weld line (see drawing below) shall mandatorily be
filled. Filling up to the rib of the skirt portion of the fitting is useless and may introduce unnecessary
potential distortion.
Page 12 of 21


__________

Reinforcement pads or saddles required by specifications and drawings shall be same material as
the main pipe (unless specified otherwise) and shall be formed and countered to provide a good fit
to both main and branch pipe.
Branch reinforcement pads shall be provided with a minimum 3.0 mm tapped holes for leak
detection, venting and testing facilities. The holes to be sealed with grease after testing completed
to avoid corrosion ingression.
For DSS, stainless steel and non -ferrous alloys spool which are unpainted shall be cleaned by
pickling & passivation to removed all marking and contamination.

4.4.6.3

Storage and issue of consumables

Welding Consumable shall be controlled follow approved procedure 1305-XXXX-00-Q-KA-00009 Welding Consumable Control Procedure and producer’s instructions.

4.4.6.4

Qualification of welders and welding operators.

All welding procedures, welders & reference to be used and qualified in accordance in ASME
section IX.
Performance qualifications will be carried out for all welders and welding operators in accordance
20377.PIP.MEC.FUN_1_Functional Specification – Piping Weld Examination General Requirements
and the requirement of ASME.
All welders should always keep their identification cards at all times with their name and number
plus a photograph, signed by CONTRACTOR and COMPANY.
The qualification limits and ranges for WPS/ PQR and welders will to be based on ASME.

Page 13 of 21


__________

4.4.6.5

Tack Welds

Prior to performing main welds, tack welds shall be done by GTAW/SMAW as the approved WPS.
Tack welds shall be made by qualified welders.

Tacks welds shall be performed in penetration and workmanship. The length and number of tack
welds for the diameter of pipe being welded shall be specified as follows (see table):
DIA (mm)

LENGTH OF TACK

NUMBER OF TACK

UP TO 50 mm

MIN 10 mm

MIN 3

50 TO 150 mm

10 - 15 mm

3-4

20 - 25 mm

3-6

OVER TO 150 mm

Tack weld bead shall be accurately cleaned by grinding before performing main welds.

4.4.6.6

Temporary Attachments

Piping fabrication and installation shall be achieved by use of clamps, jigs, fixtures, etc.
The use of cleats, bridge pieces, tacking strips or other attachments welded temporarily to pipe
work to facilitate fabrication shall be of the same or equivalent material as the pipe work to which
they are supposed to be attached.
Initial fitting up can be achieved using temporary bridge tacks across the groove.
All area to be attached by welding shall be inspected by MT or PT after removal the attachment of
pipe support.

4.4.6.7

Threaded and Socket Welds

When socket pipe fittings and valves are used, the pipe face shall be spaced approximately 1 to
1.5mm clear from root face of the socket to avoid ’’bottoming’’ which could result in excessive weld
stress and possible cracking. Socket weld shall be welded at least two passes.
In piping system, all thread joint shall be tightend by using suitable wrench.
All surfaces of threaded joints shall be checked before connection, and any dust, oxide and grease
shall be removed.
Where seal weld of thread joints are intended to use, all following condition shall be met:
Materials shall be weldable
The joints shall be made up clean and without the use of tape and compound
The weld shall cover exposed threads
The welding procedure cause damage to threaded fittings, eg… valve soft seats.
Welding shall be carried out by qualifed welders.

Page 14 of 21

__________

No other satisfactory mean of jointing are available.

4.4.6.8

Material Segregation

Direct contact between carbon steel and DSS, stainless steels or non - ferrous alloys is not
permitted.
Tools and wire ropes containing carbon steel, grinding wheels and discs contaminated with carbon
steel shall not be used on stainless steel and non - ferrous alloys.
Tools to be used for fabrication of stainless steel and non - ferrous alloy piping and piping
components shall be stored separately to avoid mixing with tools previously used on carbon steel
fabrication work.

4.4.6.9

Tolerance

Pipe connection points shall be within +/- 10mm in any direction measured from the datum point.
Flange facings shall be parallel with the theoretical plane within 0.5°. Rotation of flange facing shall
be max 1.5 mm measured on the bolt circle diameter.
For pressure vessels, heat exchangers, etc. tolerances shall be according to the selected design code.
Standout shall be measured from the Datum Point and shall be within 10 mm.
All angular dimensions of bends and branches shall be maintained within ± 1 degree.
CONTRACTOR is responsible fabrication pipe spool dimension as piping drawing. Dimension
tolerances shall be following in the Appendix 1.

4.4.6.10 NDE and repair of defect

Extent of welding test (NDE) shall be examined in accordance with drawing indicated and NDE
requirement in the 20377.PIP.MEC.FUN_1_Functional Specification – Piping Weld Examination
General Requirements.
100% weld joint shall be visual.
NDE and visual inspection shall be performed in accordance to 20377.PIP.MEC.FUN_1_Functional
Specification – Piping Weld Examination General Requirements and ASME B31.3 for piping.
Root concavity and undercut is not permitted.
The surface of repair welding will be cleaned thoroughly before welding in accordance with
applicable WPS.
All repairs shall meet the inspection requirements and acceptance standards for the original
material. Major repairs shall be inspected by Client who shall be notified in advance of starting the
repair. Welding repair shall be performed following the approved WPS.
Extent of NDE / penalty of weld joint shall be applied refer to 20377.PIP.MEC.FUN_1_Functional
Specification – Piping Weld Examination General Requirements, section 2.2.1.
Page 15 of 21


__________

Standar of acceptance and weld reject ratio shall be following requirments in the GS
20377.PIP.MEC.FUN_1_Functional Specification – Piping Weld Examination General Requirements.

4.4.6.11 Protection and storage of pipe material
Upon delivery of pipe, checks will be made to ensure that all end covers are in place to prevent
ingress of dirt and moisture.
After final completion of carbon spool fabrication, carbon spools will be transferred to the painting
area. Before transfer to painting area, spools should be blown thru or internally swabbed to remove
contaminants.
After completion of painting, the spools shall be stored on wooden pallets. DSS, stainless steel, high
alloy spools are transferred to the pipe stock yard directly and segregated from CS. spools.

All pipe ends will be protected by caps, plugs. Flange face and thread connection shall be protected
by suitble plug, flange cover and thread protectors during fabrication & erection.
All threaded nipples should be protected using waterproof tape or equivalent material to prevent
damage to the threads.
All quipment shall be protected and preservation during storage, installation, erection according to
the Vendor Specification.
Valve handles, wrenches, etc. are to be issued from warehouse with valves and shall be fastenned
on the line as close as possible on the valves, as soon as possible the valves to be erected.
Fastenning must be done by using steel bands.

4.4.6.12 Painting
Painting shall cover whole piping system including bolt and accessories. Painting for piping shall be
perform according to Surface Preparation And Painting Procedure (whichever is aplicable).
All field weld joints shall be not insulated and painted for examintion during hydro test. Shop weld
shall be painted with first coat only before erection.
For pipe spool (Stainess Steel and Duplex) which not applied painting shall be cleaned by pickling
whole the ouside face of the pipe and protected by cover canvas before moving to site for
installation.
All painted spools shall be layouted in dedicated area at final position before erection. Spools shall
be not imbricated during moving and storage.
Painted spools shall be placed on wooden pallets and supports which are isolated by rubber to
avoid directly contact between spools and supports to prevent damaged of painting layer of the
spool. Canvas shall be used to cover all painted spool storage in the layout area at final position.

Page 16 of 21


__________

For installation, spools shall be lifting and moving using web slings. Wire slings or chain is prohibited

for lifting and moving pipe spools during installation. All obstacles on the way to move the spool into
position to be cleared before installing and special care to be taken during installation to ensure no
any collision that may cause unsafe and damage of painting layer of the spools.
When hotwork occurs, the spools shall be covered to prevent sparks, slags that cause damage of
surface of the spools.
Using pipe spool for lifting other material is not permitted.
Peeling, hammering and any mechanical impact on the pipe is strictly prohibited.

3.5. Installation
3.5.1.

Pipe work erection

All piping work shall be completed in accordance with approved piping drawing such as plot plans,
sections, general arrangements, isometrics drawing, piping material classes, pipe support schedules,
standard, special support details, spools drawings and relevant vendor drawings as applicable.
The pipe spools shall be air blow with high pressure before lifting on topside in order to remove all
loose scale, weld spatter, sand and other foreign material.
Any modifications of pipe routing due to interference will be immediately notified to COMPANY and
reflected on “AS – BUILT” drawings.

Field copy to be provided earliest in case rerouting

configuration may be undesirable to COMPANY for any reason. No stress critical piping shall be
modified prior to COMPANY approval.
Final painting of all field butt welded joints shall be applied only after successful completion of
hydrostatic test.
Pipe work shall be erected on permanent supports designated for the line. Temporary supports shall
be kept to an absolute minimum, but to an extent sufficient to protect nozzles and adjacent piping
from excessive loads during the erection.

Pipe work shall be fitted in place without springing or forcing to avoid undue stressing of the line or
strain being placed on a vessel or item of equipment, etc.
All temporary pipe spools and supports that are aids to erection, testing / flushing, sea-fastening,
etc. are to be specially marked for removal identification.
Field modification of prefabricated piping shall be performed in strict accordance with this
specification and the applicable code, standard or recommended practice.
All weld slag, burrs and all foreign matter shall be removed from the piping prior to closure.
All lines shall be installed true and plumb except where specifically noted on the drawings.
Page 17 of 21


__________

Installation of piping shall be scheduled so that no undue strain will be inflicted on equipment due
to lack of support, dead weight or misalignment.

3.5.2.

Flange joints

Flanges shall be clean and free from any deleterious matter (e.g rust, dirt or other contamination)
and totally free of damage on the gasket or sealing face/ groove before assembly.
Flange bolts shall be tightened evenly and sequentially with equal pressure on the gasket to avoid
distortion or overstressing of equipment nozzle.
Flange joints that are insulated and subjected to N-2 leak testing shall be left until leak testing is
complete.

3.5.3.

Equipment flange connection

Flange covers shall be retained on all flange connections to valve or equipment, until ready to
connect the mating piping.
All equipment shall be blanked, either by pressure test spades/ blinds or temporary closures to
prevent the ingress of debris from internal pipe.
Piping shall be erected and supported in the manner that will not put undue strain on pumps,
compressors, tanks, vessels, or orther equipment. Adjustment of piping by local heating is
prohibited.
The procedure for connection of piping to equipment shall be as follows:
After equipment has been set the pipe shall be connected to equipment without making any tight
connection to flange.
Full face gasket shall be used on piping connecting to equipment with flat face flanges.
Flanges shall be checked to assure that no strain is induced on the equipment. If pipe is not correct
alignment, it shall be removed and corrected. The correction in alignment shall not be made while
the pipe is connected to the equipment.
Scratch flange face shall be repaired by re-machining in the workshop or shall be replaced.
After alignment is found correct, the flange shall be carefully ‘‘ bolted up ’’ with the stud bolt
centred in the flange and the nuts having equal thread showing.

3.5.4.

Gaskets

Gaskets shall be treated in accordance with manufacturers’ instructions. Gaskets shall be replaced
after opening or dismantling of flange connections.

Page 18 of 21


__________

After cleaning the flanges for make-up, dry gaskets shall be inserted. Flat gaskets shall be centered
by the flange bolts. Centering rings of spiral wound type or RTJ. type gaskets shall be properly
centered.

3.5.5.

Pipe support

Pipe supports shall be in accordance with the pipe support standard and relevant pipe support
detail drawings.
Piping shall not be forced to fit with support locations in such a manner that additional stress is
introduced.
Where spring support are installed, the spring shall locked gagged until commissioning/ start up.
All piping shall be arranged to facilitate supporting, and shall be planned for ease removal of
equipment for inspection and servicing. Pipes shall not normally be supported by other pipes, i.e.
individual supporting is required.

3.6. Testing
3.6.1.

General

Contructor shall perform the work necessary to successfully hydrostatically or pneumatically the
piping in accordance with ASME B31.3.
Contructor shall submit the hydrotest procedure for approval before perform the work.
All joints including welds are to be left un-insulated for examination during testing. Shop welds to be
primary coated only before installation on topside.
Vents, drains, releif valves shall be used to prevent damage to piping system due to thermal
expansion, or other harzadous conditions during testing.

Flushing shall be performed before hydrotest to remove all loose scale, weld spartter, sand and
other foreign material.
A separate team with suitable equiments shall be assigned and desgnated for perform hydrostatic
testing. These shall be conducted in a safe and workmanlike in accordance with accepted testing
procedure.
No testing to be performed without witness of the COMPANY representative.

3.6.2.

Material, equipment & test medium

Constructor shall supply all neccessary testing equipments (pumps, compressors, pressure gauges,
chart recoders…) and testing medium.

Page 19 of 21


__________

The test medium shall in general be fresh water required certification approved by COMPANY before
use for hydrostatic test. Sea water never to be used as a testing fluid.
Air for pneumatic where applicable shall be dried and filtered before use for testing.

3.6.3.

Pressure testing

Pressure test shall be followed in accordance with approved Piping linelist and Piping Flushing and
Hydrostatic Test Procedure.
Pressure test shall be maintained for 30minutes to detect seepage and to permit thorough

inspection.
When hydrostatic test is not impracticable and subject to preliminary approval of COMPANY, piping
may be pneumatically tested.

3.6.4.

Drying after test

All piping shall be completely drained of all testing fluid. RE
Piping shall be blow down with air, and air maintained through piping until there is no trapped of
water and that the piping is dry.
This in particular shall apply to all stainless steel piping.

4.

REPORTING
All status of report, schedule pertaining to spool and materials shall be prepared:
 Spool fabrication record
 Weekly fabrication status report
 Material summary report

Page 20 of 21


__________

Page 21 of 21