Applicable standards: 1.Basic design:Api600 & Ansi B16.34 2.Socket-weld(S.W):Ansi B16.11 3.Screw end(S.E):Ansi B1.20.1 4.Valves test and inspect:Api598 5.Standard material:A105.LF2.F5.F11.F22.F304.F304L.F316.F316L Features: 1.Reduced or full port 2.Lift or swing check valve 3.Spiral wound gasket of stainless steel 4.Bolted bonnet or welded bonnet 5.Scoket welding or threaded ends 6.Replaceable or integral hard faced seat 7.Size:1/2"-2 1/2"