This Standard specifies the 2 layer external extruded polyethylene coated steel pipes (hereafter referred to as "coated steel pipes"）mainly used for underground services transporting gas, oil, water, etc.and protecting cables. This Standard is generally applicable to coated steel pipes of outside diameters 21.7 mm (nominal diameter 15A or (1/2)B) to 812.8 mm (nominal diameter 800A or 32B). The coated steel pipes are usually used at temperatures in the range of -20 ℃ to +40 ℃.