GB/T8162-1999 (Seamless Square Pipes for Structural Use). It is mainly used for general structures and mechanical structures. Its representative material grades include carbon steels such as Grade 20 and Grade 45, and alloy steels such as Q345, 20Cr, 40Cr, 20CrMo, 30-35CrMo, 42CrMo, etc.

GB/T8163-1999 (Seamless Square Pipes for Fluid Transportation). It is mainly used for fluid transportation pipelines in engineering projects and large-scale equipment. The representative material grades are 20, Q345, etc.

GB3087-1999 (Seamless Square Pipes for Low and Medium Pressure Boilers). It is mainly used for pipelines that transport low and medium pressure fluids in industrial boilers and domestic boilers. The representative materials are Grade 10 and Grade 20 steels.

GB5310-1995 (Seamless Square Pipes for High Pressure Boilers). It is mainly used for fluid collecting boxes and pipelines that resist high temperature and high pressure in boilers of power stations and nuclear power plants. The representative material grades are 20G, 12Cr1MoVG, 15CrMoG, etc.

GB5312-1999 (Carbon Steel and Carbon-Manganese Steel Seamless Square Pipes for Shipbuilding). It is mainly used for Class I and Class II pressure-resistant pipes for ship boilers and superheaters, etc. The representative material grades are 360, 410, 460 steel grades, etc.

GB1479-2000 (Seamless Square Pipes for High Pressure Fertilizer Equipment). It is mainly used for pipelines that transport high temperature and high pressure fluids in fertilizer equipment. The representative material grades are 20, 16Mn, 12CrMo, 12Cr2Mo, etc.

GB9948-1988 (Seamless Square Pipes for Petroleum Cracking). It is mainly used for boilers, heat exchangers and their fluid transportation pipelines in petroleum refineries. The representative material grades are 20, 12CrMo, 1Cr5Mo, 1Cr19Ni11Nb, etc.

GB18248-2000 (Seamless Square Pipes for Gas Cylinders). It is mainly used for manufacturing various gas cylinders and hydraulic cylinders. The representative material grades are 37Mn, 34Mn2V, 35CrMo, etc.

GB/T17396-1998 (Hot-Rolled Seamless Square Pipes for Hydraulic Props). It is mainly used for manufacturing hydraulic supports, cylinders and columns in coal mines, as well as other hydraulic cylinders and columns. The representative material grades are 20, 45, 27SiMn, etc.

GB3093-1986 (High Pressure Seamless Square Pipes for Diesel Engines). It is mainly used for high pressure oil pipes in diesel engine injection systems. These square pipes are generally cold-drawn pipes, and their representative material grade is 20A.

GB/T3639-1983 (Cold-Drawn or Cold-Rolled Precision Seamless Square Pipes). It is mainly used for square pipes with high dimensional accuracy and good surface finish in mechanical structures and carbon pressure equipment. The representative materials are Grade 20 and Grade 45 steels, etc.

GB/T3094-1986 (Cold-Drawn Seamless Square Pipes and Special-Shaped Square Pipes). It is mainly used for manufacturing various structural parts and components, and its materials are high-quality carbon structural steels and low-alloy structural steels.

GB/T8713-1988 (Precision Inner Diameter Seamless Square Pipes for Hydraulic and Pneumatic Cylinders). It is mainly used for manufacturing cold-drawn or cold-rolled seamless square pipes with precise inner diameter dimensions for hydraulic and pneumatic cylinders. The representative materials are Grade 20 and Grade 45 steels, etc.

GB13296-1991 (Stainless Steel Seamless Square Pipes for Boilers and Heat Exchangers). It is mainly used for boilers, superheaters, heat exchangers, condensers, catalytic pipes, etc. in chemical enterprises. These are square pipes that resist high temperature, high pressure and corrosion. The representative material grades are 0Cr18Ni9, 1Cr18Ni9Ti, 0Cr18Ni12Mo2Ti, etc.

GB/T14975-1994 (Stainless Steel Seamless Square Pipes for Structural Use). It is mainly used for square pipes with atmospheric and acid corrosion resistance and certain strength in general structures (decoration of hotels and restaurants) and mechanical structures of chemical enterprises. The representative material grades are 0-3Cr13, 0Cr18Ni9, 1Cr18Ni9Ti, 0Cr18Ni12Mo2Ti, etc.