This Standard specifies the 3 layer external extruded polyethylene coated steel pipes (hereafter referred to as "coated steel pipes")mainly used for the straight pipes of pipelines for underground services transporting gas, oil, water, etc. This Standard is generally applicable to coated steel pipes of outside diameters 76.3 mm (nominal diameter 65A or 2(1/2)B) to 1 625.6 mm (nominal diameter 1600A or 64B). The coated steel pipes are usually used at temperatures in the range of -40 ℃ to +60 ℃.