What are the application scope and technological processes of plastic-coated steel pipes

Plastic-coated steel pipes, also known as plastic-coated pipes, steel-plastic composite pipes, or plastic-coated composite steel pipes, are steel-plastic composite pipes with a steel pipe base. A layer of plastic anti-corrosion coating is fused to the inner surface of the steel pipe or to both the inner and outer surfaces through processes such as spraying, rolling, dipping, or suction. Plastic-coated steel pipes have excellent corrosion resistance and low frictional resistance. Epoxy resin-coated steel pipes are suitable for conveying media such as water supply and drainage, seawater, warm water, oil, and gas. Polyvinyl chloride (PVC) steel pipes are suitable for conveying media such as drainage, seawater, oil, and gas.

First, the application scope of plastic-coated steel pipes:
1. Used for chemical fluid transportation.
2. Buried pipes and road crossing pipes for electrical wires and cables.
3. Ventilation pipes, water supply, and drainage pipes in mines and shafts.
4. Used in urban sewage pipelines.
5. Various forms of circulating water systems. Plastic-coated steel pipes have excellent anti-corrosion performance, with an anti-corrosion time of up to 50 years.
6. Used in fire-fighting water supply systems.
7. Water supply and drainage for various buildings.

Second, the manufacturing process of plastic-coated steel pipes:
1. Upon arrival at the factory, the coating material, after passing quality inspection, directly enters the electrostatic spraying process; unqualified materials are returned to the manufacturer.
2. Upon arrival at the factory, the base steel pipes for plastic coating undergo end treatment after passing quality inspection. First, burrs and weld seams at the pipe ends are ground smooth (weld bead height should not exceed 0.5mm).
3. After the end of treatment, the plastic-coated steel pipes undergo pickling (pickling concentration not exceeding 30% hydrochloric acid, soaking in the pickling tank for at least 3 minutes). For smaller diameter pipes, sandblasting can be used for rust removal.
4. After pickling, the pipes undergo phosphating. The pickled steel pipes are immediately immersed horizontally in the phosphating tank and then removed. The purpose is to create a phosphating film on the surface of the steel pipe, which is less susceptible to oxidation in a short time, preventing further corrosion.