API6D check valve is self-actuated and designed to prevent fluid from flowing back into the systems swing check valves are fully manufactured and tested to American Petroleum Institute (API) 6D and American National Standards Institute (ANSI) B16.34 specifications.Full Port Swing Check Valves are all designed to operate without any assistance, reacting to dominate flow direction. API6D swing check valve Features Full Open Piggable Design Suitable for Vertical or Horizontal installation Welding seat rings or Renewable seat rings Design and Manufacture: API6D or ASME B16.34 Inspection and Test: API 598 End flange dimension: ASME B16.5, ASME B16.47(API 605 ,MSS SP44) BW end dimension: ASME B16.25 Face to face,end to end: ASME B16.10 Pressure-temperature ratings: ASME B16.34 NACE: NACE 0175 Size Range: 2鈥?鈥?36鈥?br/> Pressure Range: ASME Class 150- 2500LB Materials:ASTM A216 WCB WCC;ASTM A217 WC1 WC6 WC9;ASTM A351 CF8,A351 CF8M,A351 CF3,A351 CF3M,A351 CN7M;.ASTM A352 LC1 LCB LCC LC3 Hastelloy C276,Monel,Titanium and Alloy 20(Cast Steel, Alloy Steel, Stainless Steel, Special Steel)low price Swing Check Valve website:http://www.cgvvalve.com/check-valve/swing-check-valve/