Under ground Pipe Installation (For SSC)

U/G Piping Installation Procedure

Contract No : H9301Project Title : South Steel ProjectLocation : JizanClient : SSC

0 02Jan2011 Issued for Information

Rev. Date Description Prp’d Chk’dRev’d

(QA)Rev’d

Client

App’d

SSC-stx co. ltd South Steel-Project of In Saudi Arabia

U/G Piping Installation ProcedureDoc.No.:Rev. : APage : 2 of 11

Table of Contents

1. Scope

2. References

3. Excavation

4. Coating and Wrapping

5. Backfill

6. Inspection and Examination

7. Attachment



1.0 Scope

This procedure describes the general requirements of underground piping

work which include the performance of all activities such as excavation work,

backfilling, protective coating and wrapping of carbon steel pipe.

2.0 References

2.1 The related procedures which supplement this procedure are as follows :

- STX STD. Specification

Doc. Underground Piping installation and Testing

- General Welding Procedure.

- Piping Fabrication and Installation Procedure.

2.2 The codes and standards applicable to this procedure are as described in

Piping Fabrication and Installation Procedure.

3.0 Excavation

3.1 Depth of burial of pipes shall be in accordance with Piping Arrangement

Drawings. Excavation shall be done considering the safety of the work,

whereby protective measure shall be taken to prevent side wall collapse which

can cause accident to personnel.

3.2 Before excavation, it must be confirmed that there is no other buried

installation around the place of excavation.

3.3 Type of pipe bed for the pipe shall be granular soil bed.

3.4 Under roads and in trucking areas all underground pipe work shall be

protected from damage by superimposed loads by the provision of sleeves

surrounded by reinforced concrete encasement.

4.0 Coating and Wrapping



The following requirements can be changed per specification and/or contract.

4.1 Materials

4.1.1 Prime

The primer shall compatible with and from the same source as the tape

wrapping.

4.1.2 Tape wrapping

Tape shall be nonwoven Spunbond Polyester fabric, with adhesive shall be

unaffected by bacteria, fungus and other microorganisms.

4.1.3 Coating for Valves, Flanges, and Patchwork Irregular shaped components

shall be coated with Polyken #938 or Tape coat TC mastic and wrapped with

tape.

4.2 Applied Coating and Wrapping

4.2.1 Joint and regular shaped fittings.

1) Coating and wrapping for field weld joints shall only be done after all

nondestructive examinations (NDE) and pressure testing are completed

and be left clean.

2) Remove all weld spatters, loose mill scale, loose rust, lacquer, oil, grease,

dirt, moisture and other foreign matter by wire brushing or grinding.

3) All joints and fittings shall be given a uniform coat of primer compatible with

the existing line coating system.

4) The outer layer of the line coating adjacent to the joint or fitting shall be wire

brushed back at least 50mm. The exposed undercoating and joint or fitting

shall be given a uniform coat of primer.

5) Apply one and one-quarter turns of tape over the weld prior to wrapping the

joint.

6) Each roll should overlap the adjacent roll by 10 cms. and 15 cms. overlap

for each endlaps.

4.2.2 Valves and Flanges



Valves and flanges in underground service shall have a mastic coating

sprayed or brush coated over entire exposed surface and tape wrapping shall

be applied in accordance with the requirements of Construction Specification.

Care shall be taken to insure complete coverage of valves and flanges and

that a tight seal is made with adjacent pipe wrap.

4.2.3 Risers

Risers, from underground pipe, shall be wrapped with tape to a minimum of

75mm above finished grade (top of paving) and neatly terminated with two full

laps of tape.

4.2.4 Repairs to coated pipe.

Damage areas of polyester coating, including areas of coating disbandment,

shall be cut away. Cutouts shall be smooth and tapered, without notches

longitudinal cuts or sharp corner which could develop into slits in the coating.

(i.e., circle or elliptical cutouts, not square cutouts). Rough, damaged or

protruding areas which may penetrate the protective wrap shall be removed or

repaired by abrading, filling or sanding. Field repairs shall be made using tape

system in accordance with para. 4.2.1. Field repairs shall extended to adjacent

sound coating for a minimum distance of 75mm. All repairs shall be electrically

reinspected in accordance with para. 6.4.

5.0 Backfill

5.1 When the work of backfill pipe are carried out protective measure shall be

taken in consideration to prevent accident such as side wall collages, flooding

of water etc. which can cause damage to pipe and injuries to personnel.

5.2 Care shall be taken to prevent soil and sand from following into pipes, and to

prevent pipes from re-flatting due to underground water or rainwater.

5.3 For bedding and underground pipe, the trench shall be excavated 100 to

150mm below the pipe and filled with granular soil material to a height of at



least the middle of the pipe. Backfill material paced in an excavated trench

shall be compacted with equipment which will produce the degree of

compaction specified.

5.4 In case additional soil and sand for backfilling contain gravel, crushed stone

etc. this shall be used only for upper portion of underground pipes to prevent

damage to pipe coatings.

5.5 Back-filling shall be done with appropriate tamping and 50-100mm overlapping

shall be maintained. Tamping may be done by any one of the following :

- Water binding method

- Rammer method

- Vibrator method

- Compact roller method

- Combination of above methods

The amount of water used in compaction shall be limited to that indicated by

Modified Proctor Test; through soaking or flooding shall not be allowed.

5.6 Back-filling shall be done in layers of uniform thickness is dependant upon the

compaction equipment.

5.7 Backfill material to be used shall be suitable soil, sand or gravel.

5.8 Back-filling shall only be done after coating and wrapping of welding portions is

completed.

5.9 Pipe supports such as wooden sleeper, sand bag may be installed for aligning

as well as preventing subsidence or movement of pipes, if necessary. After

alignment, wooden sleepers shall be removed and sand bags shall be splited.

6.0 Inspection and Examination (the different requirements can be applied to:)

6.1 Inspection prior to coating and wrapping



The surface to be coated and wrapped shall be dry and clean of rust, oil or

other foreign materials.

6.2 Inspection for coating and wrapping materials.

Types and specification of these materials shall be checked before application.

6.3 Appearance

Finished conditions of coated and wrapped parts shall be inspected visually to

confirm that these materials are fully clinging to the surface of pipe.

6.4 Pin-hole Test

After coating and wrapping operating have complete, the surface shall be

tested with an electrical holiday detector set at 8,000 to 10,000 volts D.C. Any

"pinholes" or missed shots located by the detector shall be repaired and

retested prior to shipment.

Pin hole test shall be done to check that there is a continuous coating over the

piping surface.

7.0 Attachment

7.1 Visual Inspection Record.

7.2 Coating and Wrapping Holiday Test Record.

7.3 Material Coating / Wrapping Specification.

Attachment 7.1 (Visual Inspection Record)

VISUAL INSPECTION RECORD



Project No. Report No.

Project Name Subcon Name

S/NUnitNo.

Line No.SheetNo.

JointNo.

WrappingRemarks

Accepted Rejected

Inspected By Witnessed By (STX) Approved By (SSC)

Name:

Date

Name: Date

Name:

Date

Form No. :

Attachment 7.2 (Coating and Wrapping Holiday Test Record)

Project No. Report No.

COATING AND WRAPPING HOLIDAY TEST RECORD



Project Name Subcon Name

S/NUnitNo.

Line No.SheetNo.

JointNo.

ResultRemarks

Wrapping Holiday Test

Inspected By Witnessed By (STX) Approved By (SSC)

Name:

Date

Name: Date

Name:

Date Form No. :

Attachment 7.3 (Material Coating / Wrapping Specification)



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Documents

Under ground Pipe Installation (For SSC)