Simply put, a check valve allows flow in one direction and automatically prevents back flow (reverse flow) when fluid in the line reverses direction. They are one of the few self-automated valves that do not require assistance to open and close. Unlike other valves, they continue to work even if the plant facility loses air, electricity, or the human being that might manually cycle them.
Main Parameter Specification
Design and Manufacture：ASME B16.34, API 6D
Face to Face and End to End：ASME B16.10
Pressure-temperature ratings：ASME B16.34
Inspection and Test：API598, API600 or API 6D
End Flange Dimension：ASME B16.5 (for NPS≤24, ASME B 16.47 series B, API 605, ASME B16.47 A Series, MSS SP-44）