Standards and specifications for valve pressure testing

The standards and specifications of valve pressure test are as follows:

1. Under normal circumstances, the valve is not subjected to a strength test, but the valve body and bonnet or the valve body and bonnet damaged by corrosion should be subjected to a strength test after repairing. For safety valves, the constant pressure and return pressure and other tests shall comply with the specifications and relevant regulations.

2. The strength and tightness test of the valve installation should be done. 20% of low-pressure valves should be checked randomly. If they are unqualified, 100% should be checked; medium and high-pressure valves should be 100% checked.

3. During the test, the valve installation position should be in a direction that is easy to check.

4. For valves in the form of welding connection, if the pressure test with the pallet fails, the pressure test can be carried out with a conical seal or an O-ring seal.

5. Exclude valve air as much as possible during hydraulic test.

6. The pressure should be increased gradually during the test, and sudden and sudden increase in pressure is not allowed.

7. The duration of strength test and sealing test is generally 2~3min, and important and special valves should last for 5min. The test time for small-bore valves can be correspondingly shorter, and the test time for large-bore valves can be correspondingly longer. During the test, if in doubt, the test time can be extended. During the strength test, no sweating or leakage of the valve body and valve cover is allowed.

8. The throttle valve shall not be tested for the tightness of the closing parts, but shall be tested for the strength and the tightness of the packing and gasket.

9. During the pressure test, the closing force of the valve only allows one person's normal physical strength to close; no levers or other tools (except torque wrenches) should be used to increase the force (except for torque wrenches). When the diameter of the handwheel is greater than or equal to 320mm, two persons are allowed to close together. .

10. For valves with upper seals, the packing should be taken out for a tightness test. After the upper seal is closed, check for leakage. When using gas as a test, put water in the stuffing box to check. When making the packing tightness test, the upper seal is not allowed to be in a tight position.

11. For valves with a driving device, the driving device should be used to close the valve when testing its tightness to conduct a tightness test. For manual actuation devices, a sealing test of the dynamic closing valve shall also be carried out.

12. The by-pass valve installed on the main valve after the strength test and the tightness test shall undergo the strength and tightness test on the main valve; when the main valve closing part is opened, it should also be opened.

13. During the strength test of cast iron valves, tap the valve body and bonnet with a copper hammer to check for leakage.

14. When the valve is tested, except for the plug valve that allows the sealing surface to be oiled, other valves are not allowed to be oiled on the sealing surface.

15. When the valve is pressure tested, the pressing force of the blind plate on the valve should not be too large, so as not to deform the valve and affect the test effect (if the cast iron valve is pressed too tightly, it will be damaged).

16. After the valve pressure test is completed, the water in the valve should be removed and wiped clean in time, and the test record should be made.