QINGDAO RUIKAI HEAT SHRINKABLE MATERIAL CO.,LTD
Anti-corrosion and joint wrapping construction process
Execute the standards of the PRC SY/T0413-2002: Technical Standards on Anti-corrosion PE Layer of Buried Steel Pipes
I、Steps:
1. Clear the weld joint, containing welding slag and other dirt. Then sandblast the surface to remove the rust with minimum derusting class of St0.3
2. After pretreatment of surface, then preheat the weld joint with the required temperature of 50℃-70℃.The flame of blowtorch shall be blue instead of red to prevent flame pollution. After preheating the PE layer, there is need some more winding treatment in order to strengthen adhesion between the heat shrinkable sleeve and the layer.
3. When the preheating temperature is reached, apply the prepared epoxy primer on the surface, the coating should be uniform without any nude part or foreign substance. and the thickness is about 150mm.
4. In three minutes after painting the epoxy primer, apply the heat shrinkable sleeve( if it requests dry film, you should wait about 40 minutes until the coating
is dry . Preheating the painted steel pipe again, and then heat one end of sleeve with a lap mark till to melt. Align the mark（at the sleeve’s back） then adhesive the joint quickly. Press it level with a roller and promise the hot-melt overflow evenly.
5. Heat fixing patch’s adhesive layer to melt. Lap the fixing patch on the seam and press evenly with a roller.
6. Heat the shrinkable tape from the center to periphery. Firstly shrink the joint gap and then heat and shrink it from the center to one end. Be careful that the heating shall be uniform and movement shall be gradual, so as to avoid the tape carbonization. In case of any air bubble or wrinkle during shrinkable, it is essential to roll it level with a roller to eliminate air bubbles. After shrinkage, heat the surrounding with slow fire until hot melt adhesive overflows from periphery.
7. After all the tape has shrink totally, it is essentials to heat again in order to keep the surface temperature is between150℃--180℃, and keep at least 3 minutes.
8. Quality Inspection: The surrounding of heat shrinkable tape has hot melt adhesive overflows evenly；The surface is smooth, no carbonation, crack, and so on.
II、Quality Inspection:
The surrounding of heat shrinkable tape has hot melt adhesive overflows evenly；The surface is smooth, no carbonation, crack, and so on.
Department of Engineering Technology
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