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1. heating of steel parts: hang the steel pipe after blasting and purging to the coating conveying roller table, and heat it with a heating furnace. heating to a certain temperature according to the coating thickness, pipe diameter, and pipe wall. the temperature difference is controlled at ±5°c.
2. coating: when the temperature of the steel pipe reaches the coating temperature, start the coating trolley and open the powder outlet valve to make the powder evenly adhere to the surface of the steel pipe. parameters such as the powder plastic (solidification) time are by the regulations of the powder manufacturer.
3. grinding of anti-corrosion plastic-coated steel pipes for water supply in chemical plants: after the steel pipes are coated, the inner and outer coatings at the ends of the steel pipes should be ground. grind into a gradual transition layer; the polyethylene coating on the outer surface is required to be removed within 150mm from the port, and the end of the coating is ground into a 30° groove.
plastic-coated anti-corrosion steel pipe welded joints for water supply in chemical plants
according to 4.4.5 on-site welding treatment of "plastic coating of the inner and outer walls of steel water supply pipelines" (ansi/awwa c213-96), the inner wall of the welded part of the steel pipe interface (about 50mm wide) should be cleaned out with an electric angle grinder and an electric wire wheel. the natural color of the steel pipe (st3 grade), and the width of the transition part (the edge of the original coating) is about 30mm to ensure that there is no dust, no mud, no oil stains, and no other impurities. use a ring-shaped thermal sensor to heat the welding joint area outside the pipe as a whole. the heating area should not be too small. when the temperature of the welding area is heated to 260°c, immediately implement epoxy resin powder coating (the performance of the epoxy resin powder coating should be the same as that used for steel pipes). the epoxy coating is completely matched), completes the joint, and then uses its waste heat to cool slowly to below 93°c to avoid rapid cooling.