3PE coated steel pipes are made from seamless steel pipes, spiral steel pipes, and straight seam steel pipes. The three-layer polyethylene (3PE) anti-corrosion coating, with its excellent corrosion resistance, moisture vapor permeability, and mechanical properties, has been applied in the oil pipeline industry. The anti-corrosion layer of 3PE coated steel pipes is crucial for the lifespan of buried pipelines. Pipes made of the same material can last for decades underground without corrosion, while others may leak within a few years. This is due to the different external anti-corrosion coatings they use.