The seamless steel pipe structure currently used in the project can be classified according to the cross-sectional shape, structural form and manufacturing method. According to the cross-sectional form, seamless steel pipe structure can be divided into three types: round pipe structure (CHS), square

6. GB9948-1988 (seamless steel pipe for petroleum cracking). Mainly used in boilers, heat exchangers and fluid pipelines of petroleum smelters. Its representative materials are 20, 12CrMo, 1Cr5Mo, 1Cr19Ni11Nb, etc.7. Steel pipes for geological drilling (YB235-70) are steel pipes used for core drilli