... 10, 20, 35# # #, 45, #, specifications: 6-720* 1-70mm 10 Seamless steel pipes conveying fluid GB / T8163-1999 ... 1999, 10, 20: # #, specifications: 6-720* 1-70mm 12 High pressure boiler tube steel: GB5310-1995, ... welded ASTM A106, A53, specifications:1/ 2 " -24",21.3-609.6mm 2 British standard ERW high- ... frequency welded pipe BS1387, specifications:1/ 2 " -12", ...