Standards and specifications for pressure testing of valves
Upload time：2023-05-03 16:21:34Clcks：
The standards and specifications for valve pressure testing are as follows:
1. In general, the valve is not subject to strength test, but the repaired valve body and bonnet or the valve body and bonnet with corrosion damage should be tested for strength. For the safety valve, its constant pressure, reseating pressure and other tests shall comply with the specifications of its instructions and relevant regulations.
2. The strength and tightness test should be done before the valve is installed. 20% of the low-pressure valves are spot-checked, and if they are unqualified, they should be checked; the medium and high-pressure valves should be checked.
3. During the test, the installation position of the valve should be in the direction where inspection is easy.
4. For valves in the form of welded connections, if the pressure test with a blind plate fails, a tapered seal or an O-ring seal can be used for pressure test.
5. During the hydraulic test, the valve air should be removed as much as possible.
6. During the test, the pressure should be increased gradually, and sharp and sudden pressurization is not allowed.
7. The duration of the strength test and sealing type test is generally 2~3 minutes, and the important and special valves should last for 5 minutes. The test time for small-diameter valves can be correspondingly shorter, and the test time for large-diameter valves can be correspondingly longer. During the test, if in doubt, the test time can be extended. During the strength test, sweating or leakage of the valve body and bonnet is not allowed.
8. The throttle valve is not subject to the sealing test of the closing parts, but the strength test and the sealing test of the packing and gasket should be carried out.
9. During the pressure test, the closing force of the valve is only allowed to be closed by one person's normal physical strength; it is not allowed to use levers and other tools to apply force (except torque wrench). When the diameter of the handwheel is greater than or equal to 320mm, two people are allowed to close together.
10. For valves with an upper seal, the packing should be taken out for a sealing test. After the upper seal is closed, check for leakage. When using gas as a test, check with water in the stuffing box. When doing the packing tightness test, the upper seal is not allowed to be in the tight position.
11. For valves with driving devices, when testing their sealing performance, the driving device should be used to close the valve and carry out the sealing test. For the manually driven device, the sealing test of the manually closed valve shall also be carried out.
12. After the strength test and tightness test, the bypass valve installed on the main valve shall be tested for strength and tightness at the main valve; when the closing part of the main valve is opened, it shall also be opened accordingly.
13. During the strength test of cast iron valves, tap the valve body and valve cover with a copper hammer to check for leakage.
14. When the valve is tested, except for plug valves that allow the sealing surface to be oiled, other valves are not allowed to test the sealing surface with oil.
15. During the pressure test of the valve, the pressing force of the blind plate on the valve should not be too large, so as to avoid deformation of the valve and affect the test effect (if the cast iron valve is pressed too tightly, it will be damaged).
16. After the pressure test of the valve is completed, the accumulated water in the valve should be removed in time and wiped clean, and a test record should be made.
