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.