Pttchem Sp p 121 000 Wrapping

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PTT CHEMICAL PUBLIC CO., LTD.

BRANCH I-1: OLEFINS PLANT

STANDARD SPECIFICATION

FOR

PROTECTION COATING & WRAPPINGFOR UNDERGROUND STEEL PIPING

DOCUMENT NO. PTTCHEM-SP-P-121

REV. ISSUED DATE DESCRIPTION REV. TO

SHEET

ADDED

SHEET

MADE

BY

CHECK

BY

APPROVE

0 7 Dec 05 First Issued Prathanwit Chayan

TOTAL PAGES 12

(INCLUDED THIS PAGE)


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PROTECTION COATING & WRAPPING FOR

UNDERGROUND STEEL PIPING

PTTCHEM-SP-P-121

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SECTION CONTENT PAGE

1. SCOPE 3

2. GENERAL 3

3. MATERIALS 3

3.1 Material for pipe and fittings 3

3.2 Materials for other piping 4

3.3 Wrapping tape specification 4

4. CLEANING 4

5. APPLICATION 5

5.1 Primer Coat 5

5.2 Tape Wrapping 5

5.3 Tape thickness 6

5.4 Method and procedure for tape wrapping 6

6. INSPECTION AND TEST 6

7. REPAIRS TO COATING 7

8. HANDLING OF COATED PIPING 8


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1. SCOPE

This specification covers the requirements for application and inspection of protective coating for

underground steel piping for the National Petrochemical Corporation Ltd.

2. GENERAL

2.1 Protective coating shall consist of a coating system employing Primer, Inner Tape Wrap and

Outer Tape Wrap.

2.2 The coating system shall be applied by an approved type of cleaning, priming, and wrapping.

2.3 Coating and wrapping materials shall be handled transported, stored, and applied strictly in

accordance with the Purchaser's instruction.

3. MATERIALS

3.1 Material for pipe and fittings

Materials of the coating and wrapping shall be as described below : For straight pipe and field

joints, elbow, tee, reducer.

3.1.1 Primer : Adhesive primer

3.1.2 Inner Tape and Outer Tape Wrap

for mechanical or manual : Polyethylene tape two-layer

application (0.5 mm thickness)


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3.2 Materials for other piping

Wrapping for Valve and Flange

3.2.1 Paste : Petrolatum anti corrosive compound

3.2.2 Inner Tape Wrap

for manual application : Petrolatum anti corrosive tape one-layer

3.2.3 Outer Tape Wrap

for manual application : Polyethylene tape two-layer

(0.5 mm thickness)

3.3 Wrapping tape specification

Material of wrapping Tape shall meet the following requirement.

3.3.1 Service Temperature : 0 c to 70 c

3.3.2 Thickness of Polyethylene Tape : Min. 0.5 mm

3.3.3 Delectric strength : 10 kV and over

3.3.4 Others : Manufacture's standard

4. CLEANING

4.1 The external surface of all piping shall be thoroughly cleaned before application of the protective

coating by mechanical means to the specification SWEDEN STD. St 2. (or SSPC-SP2)


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4.2 The cleaning process shall remove all oil grease, loose mill scale, weld spatter, weld slug, rust,

paint, dirt, dust, weeds, and any other foreign matter from the pipe external surface.

4.3 Oil and grease shall be removed using a suitable solvent such as naphtha or similar. Kerosene

shall not be used for cleaning.

4.4 Manual cleaning shall be carried out by means of file, wire brushes, etc. which are capable of

producing a surface finish to the standard required in par. 4.1

5. APPLICATION

5.1 Primer Coat

5.1.1 Primer shall be thoroughly stirred before drawing from the drum. The approved thinners may

only be added to the primer.

5.1.2 Primer shall be applied to the piping system by means of blushes. The priming coat shall be

continuous and free from holidays, runs and globules, and special care shall be taken to ensure

continuity of primer film at welds.

5.1.3 Primer shall be applied at an average rate of 0.12 litters per square meter, subject to confirmation

according to manufacture.

5.2 Tape Wrapping

5.2.1 Immediately after application of the primer, the piping shall be applied with Inner Tape Wrap and

Outer Tape Wrap. The tape wraps shall be applied with tension controlled to provide a uniform,

tightly adhering coating free wrinkles, puckers, voids, or breaks.

5.2.2 The tape wrapping shall be provided the following minimum overlap under all conditions :


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Item PE Tape width PETROLATUM

Tape width

Minimum Overlap

Pipe 150mm --- Min. overlap will be

Fitting 100mm --- 55% width of wrapping

Flange, Valve 50mm 2" to 4" 100mm one-layer

6" to 10" 200mm

12" to 300mm

5.3 Tape thickness

5.3.1 Total tape thickness shall be minimum 2.0 mm

5.4 Method and procedure for tape wrapping

5.4.1 Straight pipe see page 9

5.4.2 Field joints see page 9

5.4.3 Elbow see page 10

5.4.4 Tee see page 11

5.4.5 Reducer see page 11

5.4.6 Flange, Valve see page 12

6. INSPECTION AND TEST

6.1 All coating shall be subjected to 100 % visual inspection and 100 % inspection with an electrical

holiday detector before being lowered into the trench. Voltage is 7 kV and over, but under 10 kV.


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6.2 Visual inspection shall ensure that the coating is continuous that the overlap is correctly

maintained and that there are no wrinkles in the tape.

6.3 The holiday detector shall be used to check that there is a continuous coating over the pipe

surface. Particular attention shall be given to bends and to areas where the tape has been

spliced or repaired.

6.4 The holiday detector setting shall be checked at least twice per day while it is in use.

6.5 At no time shall be the holiday detector be permitted to remain stationary around a coated

pipeline with the operating voltage switched on.

6.6 All defects, whether discovered visually or by means of the holiday detector, shall be clearly

marked, and shall be repaired and checked again.

7. REPAIRS TO COATING

7.1 All defects in the coating shall be made good immediate after their detection before lowering the

pipe into the trench.

7.2 Holidays or localized defects in the outer Tape Wrap shall be repaired by the following procedure:

a) Strip off Outer Wrap from affected area, after ensuring that completed coating on either

side is properly secured to prevent the outer wrap from unraveling.

b) Strip off Inner Wrap and Primer from the affected area and thoroughly clean the pipe

surface.

c) Reprime in accordance with this Specification.

d) Apply patch of Inner Wrap not smaller than 150 mm x 150 mm

e) Test for repaired Inner Wrap with holiday detector before replacing Outer Wrap.

f) Replace Outer Wrap and secure firmly.


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8. HANDLING OF COATED PIPING

8.1 All coated piping shall be handled in such a way that the coating does not suffer damage.

Coated pipe shall be handled at all times with wide non-abrading belts or other equipment

designed to prevent damage to the coating. All skids used to support coated pipe shall be

padded.

8.2 If the pipeline protective coating suffers damage between the coating and laying operations, thedamaged portion of the coating shall be replaced or repaired in accordance with this

specification.


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Pttchem Sp p 121 000 Wrapping

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