Under ground Pipe Installation (For SSC)

U/G Piping Installation Procedure

Contract No : H9301 Project Title : South Steel Project Location : Jizan Client : SSC

0

02Jan2011

Issued for Information

Rev.

Date

Description

Prp’d

Chk’d

Rev’d

Rev’d

Client

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


Doc.No.: Rev. : A Page : 2 of 11

(QA)

Table of Contents 1. Scope 2. References 3. Excavation 4. Coating and Wrapping 5. Backfill 6.

Inspection and Examination

7.

Attachment

App’d


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 f looding 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 RECORD

INSPECTION



Project No.

Report No.

Project Name

Subcon Name

Unit No.

S/N


Sheet No.

Line No.

Joint No.

Wrapping Accepted

Rejected

Inspected By

Witnessed By (STX)

Approved By (SSC)

Name:

Name:

Name:

Date

Date

Date

Form No. :

Attachment 7.2 (Coating and Wrapping Holiday Test Record)

COATING

AND

WRAPPING

RECORD

Project No.

Report No.

HOLIDAY

TEST

Remarks



Project Name S/N

Unit No.


Subcon Name Sheet No.

Line No.

Joint No.

Result Wrapping

Holiday Test

Inspected By

Witnessed By (STX)

Approved By (SSC)

Name:

Name:

Name:

Date Form No. :

Date

Date

Attachment 7.3 (Material Coating / Wrapping Specification)

Remarks



Page 1 of 2




Page 2 of 2


Under ground Pipe Installation (For SSC)

Recommend Documents