... GB/T9711.1 GB/T9711.2 2.Grade:B,X42,X46,X52,X56 3.Thickness:1.5-40mm 4.OD:60-630mm 1 ... .Standard:API SPEC 5L GB/T9711.1 GB/T9711.22.Grade: ... B,X42,X46,X52,X563.Thickness:1.5-40mm4 ... high pressure boiler.Petroleum Cracking Steel Tube2012CrMo15CrMoGB9948-8810-530*1.5-3.6Seamless steel tube used for furnace ...