The main standard for large-diameter national standard spiral steel pipes is GB/T9711-1997 petroleum and natural gas industry transportation steel pipes, including GB/T9711.1 (representing A-grade steel) and GB/T9711.2 (representing B-grade steel). GB9711.2 includes quality and testing requirements that are generally higher than those specified in GB9711.1. GB9711.2 is generally applicable to steel pipes used for transporting flammable fluids and is not suitable for cast pipes.

GB/T9711 Part 1 specifies the technical delivery conditions for non alloy steel and alloy steel (excluding stainless steel) seamless steel pipes and welded steel pipes used in the petroleum and natural gas industry for transporting flammable and non flammable fluids (including water) based on basic quality and testing requirements (Class A).

This standard includes threaded and heavy-duty threaded steel pipes; Non threaded, extra light heavyweight non threaded, ordinary heavyweight non threaded, extra heavy heavyweight (XS) non threaded, and extra heavy heavyweight (XXS) non threaded steel pipes; And socket and insertion steel pipes. The dimensional requirements, measurement method regulations, gauge technical requirements and calibration, and instruments and methods for inspecting threads and thread gauges are given in GB/T9253.4, GB/T9253.7, and SY/T5994, and are applicable to the products involved in this standard.

This standard includes steel grades L175, L210, L245, L290, L320, L360, L390, L415, L450, L485, and L555, as well as intermediate steel grades between L290 and higher grades listed in Table 2. The ordinary heavyweight unthreaded phase ultra light heavyweight unthreaded steel pipes shown in Tables 9A and 9B, as well as threaded steel pipes with nominal dimensions greater than 12 (see Table 6), are marked with outer diameter dimensions. For other steel pipes, the size marking is the nominal size of the steel pipe.

In each chapter of the main text of this standard, where the size boundary line (or size range) of the steel pipe is indicated, except for the nominal size indicated, it refers to the outer diameter size. These outer diameter dimension lines and ranges also apply to the corresponding nominal dimensions.

Main materials of large-diameter national standard spiral steel pipes

Q235A、Q23b、Q345、 L245、L290、X42、 X46、X70、 X80。