Do the plastic-coated steel pipes inside and outside need to be anti-corrosion and oil-painted

If the inside and outside are fully coated with plastic, anti-corrosion oiling is not required. If the inside is plastic-coated and the outside of the pipe is only insulated, anti-corrosion oiling is not required. If the inside is plastic-coated and the outside of the pipe is directly exposed, anti-corrosion oiling is required.

Internal and external plastic-coated steel pipes are made by melting a layer of polyethylene (PE) resin, ethylene-acrylic acid copolymer (EAA), epoxy (EP) powder, and non-toxic polyethylene resin on the inner wall of the steel pipe with a thickness of 0.5 to 1.0 mm. Steel-plastic composite pipes composed of propylene (PP) or non-toxic polyvinyl chloride (PVC) and other organic substances not only have the advantages of high strength, easy connection, and resistance to water flow impact of steel pipes but also overcome the problem that steel pipes are prone to corrosion when exposed to water. Due to shortcomings such as pollution, scaling, low strength of plastic pipes, and poor fire protection performance, the design life can reach 50 years.

The disadvantage is that bending is not allowed during installation. During thermal processing, electric welding, and cutting, the cutting surface should be painted with the non-toxic room-temperature curing glue provided by the manufacturer to repair the damaged area.