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

Steel pipes can be used to transport fluids and powdered solids, exchange thermal energy, and make mechanical parts and containers, it is also an economical steel. For example, the use of steel pipes to make grids, pillars and mechanical supports for building structures can reduce the weight and