Construction technology of anticorrosive layer of polyolefin adhesive tape
The anti-corrosion layer of polyolefin adhesive tape is composed of adhesive tape and matching primer. The construction process is: surface treatment-painting primer-adhesive tape winding.
Surface treatment
1) Remove welding slag, burrs, grease, dirt and other attachments on the surface. For overhaul of the anti-corrosion layer, appropriate methods should be used to remove the original anti-corrosion layer and residues.
2) Use mechanical or sandblasting method of rust removal (if sandblasting is specified), and its quality should meet the national standard 'Steel surface corrosion grade and rust removal grade before painting' GB/T8923-1998 St3 level or Sa2 level is specified.
3) After rust removal, the defects exposed on the surface should be treated, the dust and abrasives attached to the surface should be removed, and the surface should be kept dry. When re-rusting or surface contamination occurs, the surface pretreatment must be performed again.
Applying primer
1) The time interval between surface pretreatment and primer application should be controlled within 4 hours, and the surface must be dry and dust-free.
2) The primer should be stirred evenly in the container. When the primer is thickened, the diluent that matches the primer should be added, and it can be used only when it is diluted to a suitable viscosity. The primer can be applied with a clean brush, roller or some other mechanical means.
3) The primer must be free of defects such as leakage, bubbles, clots and sagging, and a uniform film should be formed. The thickness should be greater than or equal to 30 microns. The welds should be painted carefully to prevent leakage.
4) When using primer, pay attention to safety, prevent splashing, and keep away from fire. After the primer is used, the remaining primer should be poured back into the original iron container and the container should be sealed to prevent the solvent in the primer from evaporating.
Adhesive tape wrapping
1) After the primer surface is dry (under normal temperature and natural air flow, it usually takes about 5 minutes), it can be wrapped. (When the surface is painted with a primer, when the sand is heavy or the air humidity is high, the tape should be wrapped immediately)
2) The temperature when the tape is unrolled must be above 5℃, and the construction of the anti-corrosion layer should be above -5℃ (experience has proved that the adhesive tape can be applied at a lower temperature of -30℃ , But to ensure the unwinding temperature). When the ambient temperature is lower than -10℃, in order to ensure that the adhesive tape has good adhesion, it is advisable to use a blowtorch to heat the steel pipe and to bake the adhesive tape layer.
3) For the welding seam, if necessary, it is advisable to fill and reinforce it with a narrow strip of adhesive tape or mastic with a width of 30-50 mm (cover the seam first, and use your hand or a wooden smooth tool Compaction).
4) Use appropriate machinery or manual tools to spirally wind the adhesive tape on the primed pipe section according to the overlap requirements. The adhesive tape should maintain a certain tension and tension to make the adhesive tape The layers are tightly connected. The side seams should be parallel to overcome twisting folds.
