Standards
Design and Manufacture:ASME B16.34、API 6D；
End flange dimension:ASME B16.5(for NPS<24)、API605 or ASME B16.47 seriesA、MSS SP-44(for NPS>24)。
BW end dimension:ASME B16.25
Face to face and end to end:ASME B16.10
Pressure-temperature ratings:ASME B16.34

The Features of Check valve:Bolted Bonnet;Swing and lift disc;Metallic seating surfaces.
Body and bonnet Connection:The body and bonnet of Class 150-Class 900 check valves are usually with studs and nuts,And the body and bonnet of Class 1500-Class 2500 check valves are usually of pressurized seal design.
Body-To-bonnet Joint:Stainless steel+flexible graphite wounded gasket is used for Class150 and Class300 check valve;Stainless steel+flexible graphite wounded gasket is used for Class600 check valve,and joint gasket is also optional for Class600 check valve;Ring Joint gasket is used for Class900 check valve;Pressurized seal design is used for Class1500-Class2500 check valve.