ms-mech-10, ms fabrication of piping (1)

8/12/2019 Ms-mech-10, Ms Fabrication of Piping (1)

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FABRICATION OF PIPING

MS//MECH/10Revision 01Page 1 of 13

THIS DOCUMENT IS THE INTELLECTUAL PROPERTY OF DESCON ENGINEERING LIMITED.ANY UNAUTHORIZED USE,INCLUDING THE MODIFICATION ANDREPRODUCTION OF THE CONTENT IS STRICTLY PROHIBITED.COPYRIGHTS ORDINANCE 2002-2008,ALL RIGHTS RESERVED

METHOD STATEMENT

FORFABRICATION OF PIPING

01 10, Jan. 2013 M.ADNAN SAM FI NAK

Rev. Comments Date Prepared by Checked by Checked ByPDIL

App roved by


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INDEX

1. PURPOSE

2. SCOPE

3. REFERENCES

4. DEFINITIONS

5. RESPONSIBILITIES

6. PROCEDURE

7. TOOLS AND EQUIPMENTS

8. SAFETY INSTRUCTIONS

9. ATTACHMENTS


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1. PURPOSE

The purpose of this generic method statement is to define the procedure for

fabrication of above ground piping under the MAKORI GPF project specification.

.

2. SCOPE

Scope of this method statement covers the following activities.

Material handling Fabrication

Welding

NDE

Inspection

3. REFERENCES

3.1 PROJECT DRAWINGS

Applicable Project Piping Isometrics .

Project Piping Layout drawings. Others.

3.2 PROJECT SPECIFICATION

Piping Specification Approved WPS. Other related Specifications.

3.3 PROJECT QUALITY PLAN (PQP)

Project Quality plan for above ground piping

3.4 CODES AND STANDARDSASME B31.3 Pressure Piping

ASME B31.1 Power Piping

ASME Section V

ASME 16.25 Butt Welded EndsASME 16.5 Pipe Flanges and Flanged Fittings

SNT-TC-1A Guidelines of American Society of NDT


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4. DEFINITIONS

CL Client

PM Project ManagerSM Site Manager

CM Construction Manager

DE Discipline Engineer

ITP Inspection and Test Plan

QC Quality ControlQCI Quality Control Inspector

PQP Project Quality Plan

PPE Personal Protection EquipmentHSE PLAN Health Safety & Environment PlanPM I Positive Material Identification.

NCR Non Conformance Report.

5. RESPONSIBILITIES

It is overall responsibility of PM/SM to organize resources to perform constructionactivities as per project specification, in compliance with quality, schedule & safety

requirements.

It is the responsibility of CM that construction activities are executed according tothe relevant project specifications, in compliance with quality, schedule & safety

requirements.

DE will ensure that all the works are performed safely as per latest Approved ForConstruction (IFC) drawings & specifications.

The relevant DE and Supervisor will ensure that all the piping work is conducted

in accordance with this method statement and project specifications

The QCI will ensure that all work is executed according to PQP and that

requirements of quality dossier are full filled.

Safety and construction supervision will be carried out under responsibility of

Client wherever required.

6. PROCEDURES METHOD OF WORKS INSTRUCTIONS

6.1 RECEIPT & STORAGEOF PIPE RAW MATERIALS

The piping raw material received from client shall be offloaded in designated laydown yard.


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During offloading, pipes shall not be dropped off the transport. A crane and

suitable certified slings shall be used. Nylon slings will be used to handle SS andcoated piping & fittings.

The pipes shall be placed on concrete blocks with wooden packing in between.

They shall be adequately supported to minimize sagging.

The piping end covers shall be kept in place to prevent foreign particle entry intothe pipes.

All material shall come with color-coding as per size, material & schedule.

The piping material shall be segregated accordingly to facilitate location of theitems. Alloy. SS, NACE, Low Temperature CS, CS and Galvanized pipe & fittings

to be stored separately.

6.2 PAINTING

Painting shall be done according to project specifications spec No.PC12002-395-05-SP-003

6.3 SPOOL BREAKDOWN

The piping isometrics shall be marked into number of spools to facilitate the

fabrication & erection work.

Each spool shall be marked with a unique number.

Each joint on the isometric will be given a unique number preparing a weldingmap for traceability. Separate numbering system will be followed for butt welds,

fillet welds, threaded joints etc.

The details of piping isometric breakdown into spools and joints will be recordedfor reference.

6.4 PIPING FABRICATION

Material will be shifted from lay down area to work shop as per relevant piping

isometric drawings

Carbon steel, low temperature carbon steel, NACE and stainless steel pipe

fabrication work will be done in separate areas. Tools & equipment compatible

with the material in fabrication shall be used.

The piping material is to be used in appropriate and economical way. All cuttings

should be collected separately as per material code and place in order to make

best use of these.

Cuttings of other then alloyed material may be considered as waste up tomaximum 1000mm, and should be stored separately.


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Pipes for socket weld joints shall be cut square

6.4.1 CUTTING AND BEVELING

6.4.1.1 BUTT JOINT

The pipes shall be cut as per dimensions mentioned in the isometric and all pipe

length shall be marked with the relevant spool No, as given in the isometric.Material traceability shall be maintained as per relevant agreed QIP.

Based on spool break down of piping isometrics, pipe lengths shall be cut 150mmextra length for pipe will be provided in spools for field adjustment. The pipe ends

for 2 inch & above shall be beveled as per approved WPS for the piping class.

The cutting and beveling of pipes shall be done by mechanical means cold cuttingbeveling machine/ lathe machine, flame cutting or plasma/ arc cutting, cutting

shall be acceptable provided that the edges are smooth.

When torch cutting or arc cutting are used for alloy steel or stainless steel, after

grinding to sound metal a dye penetrate examination shall be performed to

eliminate the possibility of surface cracks.

The fit up of pipe ends, fittings & weld neck flanges shall be done to obtain

uniform root opening. The criterion given in related WPS shall be followed.

The joint should be free of grease, oil, scales, rust or other foreign material.

The primer paint coat on pipe & fitting ends shall be removed prior to bevel endpreparation.

The pipes shall be tack welded by a qualified welder. If the pipes are of different

thickness, the larger thickness will be tapered in compliance with standard to

match the smaller thickness.

The adjacent section of longitudinally welded pipes that are to be joined by butt-

welds shall have longitudinal weld seams positioned such that they are at least

30apart from horizontal center line. The fabricator will also not locate longitudinal

weld seams on top or bottom of the pipe so that branch connections are not

located on the seam.

Reinforcement pads shall be fabricated only if required in the isometric. The

material for reinforcement pad shall be same as that for the pipe unless otherwise

authorized by Client. The size & thickness of pad will be as specified in the


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isometric. It is preferable that the pad shape is circular, however, the pad size

may be altered provided equivalent cross sectioned area is maintained as perASME requirement. The pad shall have a 1/8 NPT vent hole, drilled & tapped toNPT prior to installation of reinforcement pad.

The Flanges indicated on isometric to be supplied loose shall be tack welded with

the pipe. Full welding shall be made after site checking.

6.4.1.2 SOCKET JOINT

The pipe for welded sockets joint shall be ground to remove burrs due to cutting.

A gap between end of pipe & bottom of socket will be maintained as per Project

Specifications.

6.4.1.3 THREADED JOINT

In case of threaded pipes (for utilities piping only) screw threads shall be

concentric with axis of pipes with no burrs or stripping. The threading dies shall be

sharp & properly designated for the piping material.

6.4.1.4 GALVANIZED PIPES

The pipe work 3 inch & larger shall be fabricated in flanged spools as per design.

The size of spools shall conform to dimensions of hot dip galvanizing bath. Thesame shall be galvanized from both inside and outside.

The threaded joints of galvanized pipes shall not be seal welded. Tape/ sealant

will be used as per project specification.

6.4.2 MATERIAL TRACEABILITY

Material traceability shall be accordance to the Method StatementNo.MS/MECH/02.

6.5 WELDING.

All welding work will be according to approved WPS and B31.3 and only qualified

welders shall be employed.

Heat treatment will be indicated on WPS, where required.

The welding work piece will be shielded against high winds and rain. The wind

speed exceeding 10 m/sec and 3 m/sec for SMAW & GTAW respectively.


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The weld surface shall be cleaned with wire brush or grinding prior to welding

operations to give a surface free from rust, scale or mill coating.

Between each layer of welding any cracks, pores or welding spatters shall be

removed by grinding the surface before application of next layer.

The appearance of finished welds shall conform to ASME B31.3 code & WPS and

shall exclude any under cuts, spatters, and cracks.

All branch connections shall be joined to headers with full penetration welding.

The bore side shall be ground smooth, free from cracks.

For flange to pipe connections if welding shrinkages can lead to misalignment,two similar flanges shall be joined by inserting a temporary gasket and then

welded.

The distance between centrelines of adjacent grith butt welds and staggering of

longitudinally welded pipe for making butt weld shall be according to projectspecification.

Preheating shall be done in accordance with the welding requirement related to

each class of piping base metal material.

Welding shall be performed to ensure complete fusion of the weld deposit and thebase metal in order to obtain homogeneous bound over the entire cross section

area of the weld.

Welding current and polarities shall comply with the approved WPS. And or

instruction given by the manufactures of the filler metal.

Number of layers shall never be less then two.

6.6 POST WELD HEAT TREATMENT (PWHT)

6.6.1 GENERAL

Before starting any heat treatment process, it will be checked that welding hasbeen completed.

The temperature can be checked with the aid of thermochrome crayons or

thermocouples.

The preheating temperature shall be maintained throughout the welding cycle and

it should be done over sufficient width on either side of welds.

If ambient temperature of 00C or below preheating is mandatory even if notspecified. No heat treatment is required for austentic stainless steel.


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Thermocouples and their location on the job to be heat reated shall be checked.

Calibration certificates of the heat treating equipment shall be checked.

6.6.2 POSTWELD HEAT TREATMENT PROCEDURE

Stress relieving shall be performed as per project specification when specified forrelieving residual stresses caused by welding, cold working etc.

Stress relieving shall be performed when specified to obtain softer, more ductilematerial than is obtained by stress relieving. Normalising is the usual commercialannealing operation for low carbon steels. It shall be formed as follows:

A Heat material up to 16500FB Hold at temperature one hour per inch of thickness (but not less than 1/2

hour).C Air cool at room temperature.

Normally austentic stainless steel is not stress relieved, If relief of stress ismentioned in the project specification, then a full anneal shall be specified.

Full annealing of austentic stainless steel shall be performed when specified toobtain solution of carbides and maximum softness and ductility with adequatecorrosion resistance. It shall be performed as follows:

A Heat material to 2000

0

F).B Hold at temperature one hour per inch. of thickness (but not less than 1/2hour).

C Water steam or air blast quenched to room temperature. (If distortion isexcessive rapid air cool may be used, although this will result in decreasedcorrosion resistance).

Annealing shall be performed when specified to obtain maximum softness andductility. Full annealing is used on low carbon steels only where maximumformability is needed but is used on medium carbon and low alloy steels wherenormalising may not produce the desired properties. It shall be performed asfollows:

A Heat material to 17500F

B Hold at temperature for one hour Slow furnace cool to 10000 F.C Air cools from 10000F to room temperature.

When local annealing is applied the zone to be heated to annealing temperatureshall be at least four times as wide as the weld.

No further heating or welding shall be done after annealing.

For welding sensitive materials a hardness test shall be performed to evidencethat annealing was carried out perfectly.


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After heat treatment hardness of weld will be checked as per specification (if

required) and hardness test report shall be prepared.

A record of temperature levels and period of treatment should be maintained forreference.

After completion of process resultant graph of time and temperature will beverified and heat treatment sheet shall be prepared.

6.6.3 PRECAUTIONS

Heat treatment operations involve electrical heating up to 2000F bringinghazards of burning & electrocution due to a lot of cables & other electricequipment. Following precautions shall be taken.

A Appropriate visual & physical barrication of area to avoid unauthorizedpersonnel's entry

B To avoid physical hindrance due to other nearby activities.

C Warning signs / boards shall be installed on barrications,

D Proper dressing up of cables through appropriate routes to avoidentangling with other activities.

E ELCBs shall be installed on power supplies.

6.7 INSPECTION

The fabricated pipe spool shall be checked against project drawings to verify its

compliance.

The dimensions, angle and direction of spool and allowances for field welding

shall be according to the IFC isometrics & project specification. (ASME B.31.3

(chapter V)

NDE shall be performed as per ASME section V after PWHT if specified on

isometric drawings or project specifications.

The acceptance criteria for visual inspection shall be done according to the ASME

B.31.3. (Chapter VI).

Visible small transverse cracks & star cracks of limited thickness shall be removed

by grinding & repaired by welding. However circumferential cracks shall result in

weld rejection. The defective material will be cut out & rewelding preformed.

NDE tests shall be performed & recorded as per Piping Class, relevant Code and

Project (Welding) Specifications.

The NDE result shall be interpreted by qualified inspectors (level II)


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The fabricated support shall be painted after surface preparation as per project

specifications.

The procedure of welding pipe support attachments to pipe work shall be

generally similar as that for pipe work and qualified welders shall be employed.

Pipe support welding on piping requiring PWHT shall be done prior to the heat

treatment.

7. TOOLS & EQUIPMENTS

7.1 EXECUTION

Hand Tools Cutting, Beveling & Grinding Machines

Cranes (Mobile)

Cranes (Tower) if required

Lathe Machine

Hack Saw Trailer

Stress Relieving Equipment

Welding Machine

7.2 SAFETY

Safety helmet Safety Goggles

Gloves Safety Shoes

Welders Helmet Ear Plugs/Muffs (if required)

Dust mask (If required)

7.3 TESTING

Radiography

Ultrasonic Testing

Mage Particle Testing

Dye Penatrant


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8. SAFETY INSTRUCTIONS

During execution of the job all measure shall be adopted to ensure safe working.

DE will ensure that, PTW system shall be implemented as per client requirementsin CPF and GPF areas.

DESCON site management system (latest revision) will be implemented.

All personnel involved will use necessary PPE as required.

The workers will be made aware of safety requirements related to this activitythrough daily, weekly and monthly toolbox and safety talks.

Safety notice board will be installed.

All equipment will be inspected by E&P (DESCON) as per routine while execution

supervisor should inspect it prior to use. During transportation of pipes and other fittings, the material shall be properly

supported and tied on the Trailer. Ensure that pipes are properly wedged or blocked to avoid rolling.

Correct rigging procedure should be observed. Access and good housekeeping should be maintained in all fabrication areas. Fire extinguisher should be available in all working areas.

Proper storage, handling and use of gas cylinders will be observed.

All cylinders shall be kept in trolleys and in an upright position. Welding sets should be checked and maintained regularly for wear and tear. Waste Management should be strictly followed to keep the job site neat and

clean.

HSE shall provide due support to the execution team in the fulfillment of HSE

requirements.

9. ATTACHMENTS.

Nil.

ms-mech-10, ms fabrication of piping (1)

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