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polyethylene coating tape anticorrosion systerm Application
Date: 2015-03-30

polyethylene coating tape anticorrosion systerm Application

1. Pipe Preparation

1) Keep the pipe external surface clean and dry.

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

3) After the pre-cleaning operations, the pipe surface not smooth which may sharp the pipe coating should be burnished, the abrasive dust attached on the pipe surface should also be cleaned clearly.

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

2. polyethylene Coating tape &Wrapping application

1) Coating tape wrapping tape application consist of primer application, inner tape coating ,outer tape coating .

2) weather condition

3) When the wind &sand was strongly, when the sand and dust covered on the surface of pipe, primer ,tape etc., should not be brushing primer and wrapping the tape if there is no reliable preventive measures.

4) When air humidity is greater than 80%,or when the pipe surface is wet from any precipitation, should not be brushing primer and wrapping tape

5) The coating wrappng tape application shall be a continuous operation starting with properly prepared pipe surface . Three steps, which shall be performed consecutively, shall consist of

(1) liquid adhesive application;

(2) application of the inner-layer tape directly onto the prepared pipe surface;

(3) application of the outer-layer tape directly on top of the inner-layer tape.

6) The coating materials shall be stored in a clean, dry area. During steps 2 and 3, one or more layers of inner-layer tape and outer-layer tape may be applied as specified and approved by the Engineer in Charge.

3. Liquid adhesive Application

1) The Liquid adhesive shall be applied in a uniform thin at the coverage rate recommended by the manufacture.

2) The Liquid adhesive shall be thoroughly and continuously mixed and agitated during application to prevent settling.

3) The Liquid adhesive may be applied to the entire exterior surface of the pipe by spray-type or rug-type methods or other suitable means to cover the entire exterior surface of the pipe.

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

5) The primer coat DFT shall not be less than 25-50micron(1-2mils)

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

7) Consumption:

machine application approx. 0,1 litre/m²

hand application approx. 0,12-0.15 litre/m²

4. Application of Inner-layer-tape、

1) The inner-layer tape shall be applied directly onto the prepared pipe surface,Wrap tape application consists of hand application and machine application.

2) The tape applied temperature must be above 5 degrees, the coating construction temperature shall be more than -5 degrees as better.

3) The tape shall be spirally applied ,minimum overlap shall not be less than 50%.When applied to spirally welded pipe , the direction of the tape spiral shall be generally parallel to the weld spiral. The minimum overlap shall not be less than 25 mm.

4) When a new row of tape is started, the ends shall be overlapped at least 150 mm measured circumferentially.

5. Application of Outer-layer-tape

1) The Outer-layer tape shall be applied over the inner -layer tape using the same type of mechanical equipment used to apply the inner-layer tape.

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

6. Cutbacks

Cutbacks shall be 6inches 150 mm +/- 25 mm from the ends of each pipe. The cutbacks may be straight edge for the total thickness of the coating, or they may be tapered, as approved by the Engineer in Charge.