3PE anti-corrosion steel pipe base metal includes seamless steel pipe, spiral steel pipe and straight seam steel pipe. The three-layer polyethylene (3PE) anti-corrosion coating has been widely used in the oil pipeline industry for its good corrosion resistance, water vapor permeability resistance and mechanical properties. 3PE anti-corrosion steel pipe anti-corrosion layer is of vital importance to the life of buried pipelines, the same material pipeline, and some buried in the ground for decades do not corrode, and some years leaked. It is because they use different external coatings.