Standards

Design and Manufacture: Cast steel check valve to BS 1868, ASME B16.34 and API 6D; Forged steel check valve to API 602.
Inspection and Test: API 598 or API 6D.
End flange dimension: ASME B16.5 （for NPS≤24）、ASME B16.47 series B、API 605 or ASME B16.47 series A、MSS SP-44 （for NPS＞24）.
BW end dimension: ASME B16.25.
Socket-weld dimension: ASME B16.11.
Face to face and end to end: ASME B16.10.
Pressure-temperature ratings: ASME B16.34.
Wall thickness dimension: API 600 and BS 1868.

●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 Class 150 and Class 300 check valve; Stainless steel＋flexible graphite wounded gasket is used for Class 600 check valve, and joint gasket is also optional for Class 600 check valve; Ring Joint gasket is used for Class 900 check valve; Pressurized seal design is used for Class 1500～Class 2500 check valve.

●Seat

For carbon steel check valve, the seat is usually forged steel. The sealing surface of the seat is spray welded with hard alloy specified by the customer. Renewable threaded seat is used for NPS≤10 check valves, and welded on seat can be also optional if being requested by the customer. Welded on seat is used for NPS≥12 carbon steel check valves. For Stainless steel check valve, integral seat is usually adopted, or to weld hard alloy directly integrally. Threaded or welded on seat is also optional for stainless steel check valve if being requested by the customer.

●Standards

Design and Manufacture: BS1868 or API 6D
Inspection and Test: API 598 or API 6D
End flange dimension: ASME B16.5、ASME B16.47 A、MSS SP-44; ASME B16.47 B、API 605
BW end dimension: ASME B16.25
Face to face and end to end: ASME B16.10
Pressure-temperature ratings: ASME B16.34
Wall thickness dimension: API 600 and BS 1868