Why does the valve always fail?

In the whole process of design, manufacturing, installation, working condition, operation and maintenance, each step should not be relaxed. How to determine whether there is a problem before the valve leaves the factory or after complete installation? This needs to be checked through appearance inspection and certain performance test. Through these test results, defects can be exposed and adjusted accordingly. They can be put into use only after all tests are qualified. So, what details should be paid attention to in appearance inspection? What does the performance test include?


Appearance inspection

1. Whether there are sand holes, cracks and other defects on the inner and outer surfaces of the valve body.

2. Whether the valve seat is firmly connected with the valve body, whether the valve core is consistent with the valve seat, and whether the sealing surface is defective.

3. Whether the connection between the valve rod and the valve core is flexible and reliable, whether the valve rod is bent, and whether the thread is damaged and corroded.

4. Whether the packing and gasket are aging and damaged, and whether the valve can be opened flexibly, etc.

5. The valve body shall be provided with a nameplate, which shall include: Manufacturer’s name, valve name, nominal pressure, nominal diameter, etc.

6. The opening and closing positions of valves during transportation shall meet the following requirements:

(a) Gate valve, stop valve, throttle valve, butterfly valve, bottom valve, regulating valve and other valves shall be in the fully closed position.

(b) The closing parts of plug valve and ball valve shall be in the fully open position.

(c) The diaphragm valve shall be in the closed position and shall not be closed too tightly to prevent damage to the diaphragm valve.

(d) The disc of check valve shall be closed and fixed.

7. Spring type safety valve shall have lead seal, and lever type safety valve shall have heavy hammer positioning device.

8. The valve disc or valve core of the check valve shall act flexibly and accurately without eccentricity, displacement or skew.

9. The inner surface of valves lined with rubber, enamel and plastic shall be flat and smooth, and the lining shall be firmly combined with the substrate without defects such as cracks and bubbles.

10. The flange sealing surface shall meet the requirements without radial scratches.

11. The valve shall be free of damage, missing parts, corrosion, nameplate falling off and other phenomena, and the valve body shall be free of dirt.

12. Both ends of the valve shall be protected by protective covers, and the handle or hand wheel shall be operated flexibly without jamming.

Post time: Dec-22-2021