... 1999 GD2000 GD87-1101HG/T21635-1987 HG/T21631-1990 MaterialCarbon steel :(ASTM A234WPB,,A234WPC,A420WPL6. 20#,Q235,10#,20#,A3, Q235A, ... 20G,16Mn, ect)Alloy steel :(ASTM A234 WP12,WP11,WP22,WP5,WP9,WP91,16MnR, Cr5Mo, 12Cr1MoV ... , 10CrMo910,15CrMo, 12Cr2Mo1, ect)Stainless steel :(ASTM A403 WP304,304L,316,316L,321. 1Cr18Ni9Ti, 00Cr19Ni10,00Cr17Ni14Mo2, ect ...