合金无缝钢管GB6479-86 20G 15CrMo 12Cr1MoV 35,43,49,55,60,63.5,68x3-12 73,76,83,89,102,108,114x4-18 121,127,139,146,152,159,177.8x5-25 194.5,203,219.14,244.5,273,299,325x10-28 351,377,406,426,450,480x10-36