What are the changes in anti-corrosion methods and common defects of plastic-coated steel pipes

First, what are the changes in anti-corrosion methods for plastic-coated steel pipes?

The earliest anti-corrosion method for plastic-coated steel pipes was inner and outer polyethylene. Due to adhesion problems, it evolved to inner and outer epoxy. However, the outer epoxy layer was not resistant to impacts. Later, the third generation was developed, with inner epoxy and outer polyethylene. However, the adhesion problem still existed when a single layer of polyethylene was directly bonded to the steel pipe. Finally, it was upgraded to the fourth generation of anti-corrosion—3PE outer anti-corrosion fusion-bonded epoxy powder inner anti-corrosion pipe. 3PE outer and fusion-bonded epoxy composite steel pipes are widely used in the water conservancy industry, municipal industry, and long-distance water transmission pipelines, such as the South-to-North Water Diversion Project.

Second, what are the common defects in anti-corrosion methods of plastic-coated steel pipes?

1) During on-site construction, the curing of epoxy resin is affected by temperature, resulting in slow curing and a long construction period.

2) Because a large amount of solvent is added during construction, it easily provides an opportunity for some construction companies to cut corners (adding more solvent, diluting the coating, and increasing costs).

3) As it is a two-component compound, inaccurate hardener mixing or uneven stirring during on-site construction can easily lead to poor curing or uneven quality after curing.

4) The anti-corrosion layer uses fiberglass cloth reinforcement. Fiberglass cloth contains wax, which affects interlayer adhesion. During construction, fiberglass fibers can easily damage the skin of construction workers, making them generally unwilling to perform the work properly.