12 Procedure for Tape Coating

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LARSEN & TOUBRO LIMITEDPAGE NO.- 1 OF 6

DATE:-05.11.07MSQ UP GRADATION (EPCC 1)

PROJECT REV.NO.- 0

PROCEDURE FOR UG PIPING CORROSION

PROTECTION TAPE -COATING

PROCEDURE NO.-LT/MSQ/P/UG/TC/012

CONTENTS

1) PURPOESE

2) REFERENCE DOCUMENTS

3) MATERIALS

4) PROCEDURE

5) INSPECTION

6) REPAIR7) MACHINE LIMITATION

8) HANDLING OF COATED PIPES

9) SAFETY PRECAUTIONS

APPROVED BY L & T REVIEWED / APPROVED BY JACOBS





PROJECT REV.NO.- 0

PROCEDURE FOR UG PIPING CORROSIONPROTECTION TAPE -COATING


1.0 PURPOSE

1.1. This procedure describes guidelines to carry out tape coating of UG piping at IOCL PANIPAT

REFINERY – MSQ UPGRADATION PROJECT.

1.2. In case of conflict between this procedure and contract specification, the latter shall govern.

2.0 REFRENCE DOCUMENTS:

2.1. As per Jacobs spec. No. 3177-LSS-109

2.2. AWWA C-203 Coal tar protective coating lining to steel carbon pipeline

2.3. SSPC-SP10 steel structure Painting council, surface preparation specification

2.4. ASTM G8 test method for cathodic disbanding of pipeline coating

3.0 MATERIALS:

3.1. Protective tapes and other materials brought to site shall be as per specification.

3.2. Manufacturer’s test certificates shall be submitted for review prior to use.

3.3. The primer shall be type B as specified in AWWA C-203.

3.4. Field and laboratory test shall be carried out for each batch of primer & tape.

3.5. Primer and tape shall be supplied by the same manufacturer.

4.0 PROCEDURE:

4.1. SURFACE PREPARATION:

4.1.1. Prior to blast cleaning, all oil, grease on the pipe surface shall be thoroughly removed

by flushing with suitable solvent as per SSPC SP-1 and wiping with clean tags.

Degreased pipe metal surface shall be shot/grit blast cleaned to SSPC-SP-10 or Sa 2½ of

SIS-05-5900. This cleaning operation shall be followed immediately with priming by spraying /

brush.






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4.1.2. Blast cleaned surface shall be adequately scrubbed manually with stiff wire brush

where ever blasted surface get rusted, prior to application of primer.

4.1.3. All weld joints shall be cleaned manually with stiff wire brush/buffing wheel after

assembly and welding, prior to priming.

4.2. PRIMING:

4.2.1. Immediately after girt blasting the surface shall be applied with fast drying unmodifiedpure chlorinated rubber based coal tar synthetic primer.

4.2.2. Second coat of primer to be applied before application of coal tar enamel. The entire

surface of pipe should be primed. No specific time gap between two coats of primer needs to

be maintained but after the second coat of primer, the enamel coating should before the

primer is completely hardened.

4.3. PREPARATION OF COATING MATERIAL:

The metal drums that shall be cropped or cut on suitable platform to prevent the enamelcoming in contact with wooden cinders, grass and other forms of contamination. The enamel

shall be confirmed to Type-I or Type-II coal tar enamel as per AWWA C-203. The cropped out

pieces if enamel may not Wight more then 10 kgs. The broken pieces shall be placed in a

clean melting kettle which is made of heavy duty, MS sheet in form of closed vessel. To

maintain uniform coverage of material required quantity of enamel is heated in the kettle with

temperature range of 2300C to 2400C. Temperature of enamel can be checked by dipping

thermometer in the enamel. Thermometer shall be used in heating kettle in a such way so as

read the temperature clearly. The thermometer shall have temperature range up to 3000

C.






PROJECT REV.NO.- 0



4.4. MECHANICAL APPLICATION OF COATING AND WRAPPING :

4.4.1. The pipe shall be kept rotating on a machine having circumferential and linear motions,

while the pipes are in rotating condition, pour the hot cold enamel manually and spread

uniformly with the help of rubber brushes.

4.4.2. Simultaneously, one wrap of glass fiber tissue having properties as stated in Jacobs

specification shall be applied over the molten coal tar enamel. Initially, the wrap is held with

hand and pressed over the molten enamel. There after the revolving pipe puffs the fiber warpfrom the reel, which ensures continuous wrapping over the molten enamel with required

overlap (i.e. 13 mm).

4.4.3. Second coat of coal tar enamel as well as glass fiber tissue paper shall be applied as

per above procedure.

4.4.4. Third coat of molten coal tar enamel shall be applied next.

Final outer wrap of impregnated fiber felt shall be applied immediately over third coat of coal

tar enamel, similar to inner wrap application. The overlap at edges of all wrappings should be

minimum 13 mm. the coating shall be continuous for the full length of the pipe except 200 mmat both ends of the pipes.

Finally, carry out whit wash with Acrylic water emulsion Latex Paint Material. This application

will be carried out manually by paintbrushes. There after the pipes is lifted by suitable

methods and allowed to dry on wooden sleepers.

5.0 INSPECTION:

5.1. All stage inspection & documentation shall be carried out as per Format No. LT/MSQ/TC/020,

Rev.00

Profile gauge/comparator, for checking surface preparation as per SA 2½ , shall be madeavailable.

5.2. After application of tape coating, visual inspection shall be carried out for uniformity without

any wrinkle, irregularities and overlapping width.






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5.3. Thickness of the coal tar enamel coating shall be measured with the digital thickness gauge.

Minimal acceptable thickness shall be 4.5mm.

5.4. All coated and wrapped pipes shall be tested with the positive signalling device to indicate

any fault, holes, breaks or conductive particles in the protective coating. The test voltage shall

be 13 KV.

5.5. Peel test shall be conducted at temperature from 10ºC to 25ºC per AWWA-203 methods.

Acceptable criteria shall be as per AWWA-203.

6.0 REPAIR:

Wherever any holiday is observed or any defective work is found, remove the wrapping and

coating to the required extend from those areas by using a sharp knife. Then heated enamel

shall be applied manually over the area following the procedure described above and inner

and outer wrap applied. Holidays test shall repeated for the portion.

7.0MACHINE LIMITATION:

Machine used for coating and wrapping as described above can be used from pipes from

10’’Ǿ to 48 “Ǿ only. For pipes upto 8” Ǿ and above 48” Ǿ, coating and wrapping shall be done

manually with out rotation of pipes.

8.0 HANDLING OF COATED PIPES

The coated pipes shall be handled at all times with equipments such as wide belt slings and

padded skids designed to prevent damage to the coating. Bare cables, chains, hooks etc.

shall not be permitted to come in contact with coatings. A suitable crane may be used. Coatedpipes shall be supported at two bare ends clear from ground either on kids or sand bags.






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9.0SAFETY PRECAUTIONS

9.1. Adequate and proper PPE shall be provided to persons involved in short of grit blasting work.

9.2. Adequate and proper PPE shall be provided to persons involved in hot application of coal tar

enamel along with the wraps.

9.3. Proper fire fighting system shall be provided during application of primer and enamel coatsand all safety requirements shall be ensured for under ground trenching, lowering & back

filling.

9.4 All precaution shall be observed as per the instruction of PMC/ OWNER.


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12 Procedure for Tape Coating