External polyethylene coating is a plant-applied coating system applied externally to provide excellent anti-corrosion protection for steel line pipes and fittings, intended primarily for buried or submerged service for water or oil and gas pipeline, including two-layer (2LPE) and three-layer (3LPE) coating systems, whereby a copolymer adhesive is interposed between a bare substrate or high-performance fusion bonded epoxy and the outer layer of polyethylene which provides mechanical protection at moderate operating temperature.