DFT Valve Leak Test Infographic
DFT check valves undergo rigorous shell and seat closure pressure tests to ensure that they meet industry quality requirements. The following information shows the types of tests we perform and the standards to which our valves are held. A full illustration of these test standards can be found on our Valve Leak Test Infographic.
Shell Test
Each valve is shell tested to demonstrate the integrity of the pressure boundary. Test pressure is to be no less than 1.5 times the cold working pressure, rounded up to the nearest 25 psi increment, with water as the test medium. Acceptance criteria is zero observable leakage for the duration of the test, which varies by valve size as follows:
Test Medium | Allowable Leakage | Minimum Test Duration | |||
2″ and < | 2-1/2″ – 6″ | 8″ – 12″ | 14″ and > | ||
Water | 0 mL/hr | 15 seconds | 60 seconds | 120 seconds | 300 seconds |
Seat Test
Every valve is given a seat closure test to demonstrate that the static pressure performance is within the allowable leakage tolerance as defined by MSS SP-61. Water or air can be used as the test medium; minimum test pressures are 1.1 times the cold working pressure for water, and 80 psi for air. Acceptance criteria for metal seated valves is 40 mL/hr per inch of nominal pipe size when tested with water, and .40 SCFH per inch of nominal pipe size when tested with air. For soft seated valves, zero observable leakage is allowed regardless of test medium. Test duration varies by valve size as follows:
Test Medium | Allowable Leakage | Minimum Test Duration | |||
2″ and < | 2-1/2″ – 8″ | 10″ – 18″ | 20″ and > | ||
Water | 40 mL/hr per inch pipe size | 15 seconds | 30 seconds | 60 seconds | 120 seconds |
Air | .4 SCFH per inch pipe size |
Industry Standards
DFT check valves are subject to MSS SP-61, which establishes acceptance criteria for shell and seat closure pressure testing. MSS SP-61 is the standard seat leakage requirement for gate, globe, and check valves in the United States. Cast iron GLC and WLC models are subject to AWWA shell and seat test standards. Testing to alternative standards is available per customer request.
DFT Products
Our online catalog features a wide selection of in line and control and block valves.
In line Check Valves
- Threaded Check Valves
- Wafer (Axial flow) Check Valves
- Flanged Check Valves
- Sanitary Check Valves
- Restrictor Check Valves
- Vacuum Breaker Check Valves
Control and Block Valves
To inquire about our products, special testing methods, or additional industry standards we adhere to, contact us today.