Execution standard: GB/T9711-2017, the materials of such standard line pipes are: L245, L290, L360, L390, L415, etc.; the letters N, M, Q behind the material are respectively; those without letters are PSL1 standard, the suffix with letter N is deformation normalizing, generally seamless pipe; the suffix with letter M is welded pipe or spiral pipe, the delivery state is deformation heat treatment (straight seam welding, double-sided submerged arc welding, high frequency welding , HFW ERW); the suffix letter with Q is the delivery status of quenching + tempering;

The maximum carbon equivalent CE (IIW) of the seamless steel pipe of the PSL2 standard is 0.43%; below the specified maximum carbon content, each 0.01% decrease in carbon content is allowed to increase the manganese content by 0.06% above the specified maximum manganese content , but the maximum shall not exceed 1.35%; the sum of the five elements Cu, Ni, Cr, Mo, and V shall not exceed 1.00%.