Pipe wrap tape Applying

Pipe Wrap Tape Applying

1. Pipe Preparation

1.        Keep the pipe external surfaceclean and dry.

2.        Remove the dust, oil, weldingslag, burrs, grease and dirt on pipe surface. Pipe surface prepared up-to alevel of Sa 2 or 2 ½ or St 2/st by sand blasting. 

3.        After the pre-cleaningoperations, the pipe surface not smooth which may sharp the pipe coating shouldbe burnished, the abrasivedust attached on the pipe surface should also be cleaned clearly.

4.        If flash rusting occurs, thesurfaces must be re-cleaned by blasting as above.

2. Coating and WrappingApplication

1.        Coating and wrappingapplication consist of primer application, inner tape coating and outer tapecoating.

2.        When the wind and sand isstrong and the sand and dust are covering the surface of pipe, primer or tape,should not be brushing primer and wrapping the tape if there is no reliablepreventive measures.

3.        When air humidity is greaterthan 80% or when the pipe surface is wet from any precipitation, should not bebrushing primer and wrapping tape

4.        The coating application shallbe a continuous operation starting with properly prepared pipe surface. Threesteps, which shall be performed consecutively, shall consist of:

(1)   Liquid adhesive application

(2)   Application of the inner-layer tape directly onto theprepared pipe surface

(3)   Application of the outer-layer tape directly on top of theinner-layer tape

5.        The coating materials shall bestored in a clean, dry area. During steps 2 and 3, one or more layers ofinner-layer tape and outer-layer tape may be applied as specified and approvedby the engineer in charge. 

3. Liquid Adhesive Application 

1.        The liquid adhesive shall beapplied in a uniform and thin layer at the coverage rate recommended by themanufacture.

2.        The liquid adhesive shall bethoroughly and continuously mixed and agitated during application to preventsettling.

3.        The liquid adhesive may beapplied to the entire exterior surface of the pipe by spray-type orrug-type methods or other suitable means to cover the entire exterior surfaceof the pipe.

4.        The liquid adhesive coat shallbe uniform and free from floods, runs, sags, drips, or bare spots. The liquidadhesive coated pipe surface shall be free of any foreign substances such assand, grease, oil, grit, rust particles or dirt.

5.        The primer coat DFT shall notbe less than 25-50 micron (1-2mils)

6.        After the primer dried, thenwrapping the tape (It usually takes 3 to 5 minutes.).

7.        Consumption

a)        Machine applicationapproximately 0,1 litre/m²

b)        Hand application,approximately 0,2 litre/m²

 4.     Application ofInner-Layer-Tape

1.        The inner-layer tape shall beapplied directly onto the prepared pipe surface. Wrap tape application consistsof hand application and machine application.

2.        The tape applied temperaturemust be above 5 degrees, the coating construction temperature shall be morethan -5 degrees as better.

3.        The tape shall be spirally applied, minimum overlap shall notbe less than 50%. When applied to spirally welded pipe, the direction of thetape spiral shall be parallel to the weld spiral. The minimum overlap shall notbe less than 25 mm.

4.        When a new roll of tapeis started the end shall be overlapped at least 150 mm measuredcircumferentially.

5. Application ofOuter-Layer-Tape

1.        The Outer-layer tape shall beapplied over the inner -layer tape using the same type of mechanical equipmentused to apply the inner-layer tape.

2.        The overlap of the outer-layertape shall not coincide with the overlap of the inner-layer tape. The minimumoverlap of the applied tape and minimum end lap of two rolls shall be the sameas that of inner-layer tape.

6. Cutbacks
Cutbacks shall be 6 inches 150 mm /- 25 mm from the ends of each pipe. Thecutbacks may be straight edge for the total thickness of the coating or theymay be tapered as approved by the engineer in charge.