Butt-Welded Fittings: Standards: ASME B16.9 EN10253-1/2/3/4/5 MSS SP-43/75 Material: Carbon Steel: ASTM A234, Stainless Steel: ASTM A420, Alloy Steel: ASTM A403, Threaded Fittings: Standards: ASME B16.11 MSS SP-79 MSS SP-83 MSS SP-95 Material: ASTM A105, Socket-Welded Fittings: Standards: ASME B16.11 MSS SP-79 MSS SP-83 MSS SP -95 Material: ASTM A105 A182 A234 A350 A403 A420 A815.