high precious pipe , smooth surface NOSteel pipeStandardSteel gradeSpecificationOD×WAL×LENGTH ( ... fluid tubeGB/T8163-199910,20,Q295,Q34560~180×3.5~25×4000~120005high-pressure boiler tubeGB5310-199520G,20MnG, ... ,20,16Mn,15Mnv,12CrMo,15CrMo60~168.3×3.5~25×4000~120009Structural use of seamless steel tubesGB/ ... T8162-199910,20,45,35CrMo,40Cr60~180×3.5~25×4000~1200010Shipping use of tubeGB5312-1999320,360, ...