... 17175-1979 BS3059Part 21990Seamless Steel Tubesfor low and Medium Pressure BoilersGB3087-199910, 20ASTM A179, ASTM A192 ASTM SA179,SA192, BS3059Seamless Steel Tubes for high pressure --Chemical fertilizer ... equipmentGB6479-8610, 20G, Q345, Q390, 10MoVNb, 12CrMo, 15CrMo, 12Cr2MoISO 9329-2-1997 ASTM ...