Crack analysis of valve housing

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Valve cracking analysis

Cracking is a common problem in valve shells. The crack can be divided into surface crack, fatigue crack and stress corrosion crack according to the occurrence mechanism. Its harm is very large, it can cause leakage or other serious accidents. Therefore, cracking analysis of valve shells has always been the focus of research.

The cause of surface cracking of valve shells may be due to errors in the process of casting or forging. It is mainly caused by the unevenness of shrinkage and the bumps of sand inclusions. In addition, long-term overload operation of the valve will also cause surface cracks. As for the fatigue crack, it usually occurs near the nozzle of the valve body. This kind of crack mainly occurs due to the sudden increase of load or liquid pressure of the valve during the operation process, resulting in too much stress of the valve and causing fatigue crack after long-term overload.

As for stress corrosion cracking, it is mainly caused by the reaction between the material of valve body and the medium. It has a great relationship with the environment of valve. Generally, stress corrosion cracking will occur in acidic or alkaline environment. In addition, in the high temperature environment, when the contents of chloridion in the medium exceeds the critical value, the stress corrosion cracking will occur.

To solve this problem, we can choose to repair, anti-corrosion protection or replacement of valve shell. If the valve shell has a small area of micro-cracks, we can only use a sealant to patch it. But if it is a serious cracking that endangers the valves function and operation, we must take replacement measures on it.

Valve body should be regularly inspected and tested in the operation process to check if there are any signs of cracking or other abnormalities. According to the conditions and characteristics of the valve, professional testing agencies can be selected to carry out non-destructive testing methods to evaluate the mechanical properties of the valve body, such as x-ray, ultrasonic, eddy current, magnetic flux leakage and penetrant testing etc.

In conclusion, cracking of valve body can not be completely avoided, but in order to prevent it, the safety operation during use and regular inspection should be paid more attention to and corresponding measures should be taken to reduce potential risks.

Valve Body Cracking Analysis

Valve body cracking is a common manufacturing process defect, which seriously affects the service life of valves and the safety of work. It not only affects the normal use of valves, but also results in economic losses. Therefore, it is very necessary to analyze the cause of the cracking and take corresponding measures to respond in time.

The main reasons for valve body cracking are:

1. Improper material selection: Different materials have different performance characteristics, so it is necessary to choose the appropriate material that suits the operating environment and working conditions.

2. Inadequate care before welding: There may be impurities on the surface of the valve body parts in the process of cutting, processing and transportation. If it is not blocked before welding, it will affect the quality of welding, leading to the valve body material weak and cracking.

3. Improper welding process: When welding, improper welding process parameters and welding environments will cause incomplete fusion of the valve body and cracking.

4. High temperature and high pressure: During the operation of the valve, improper setting of the operating temperature and operating pressure will cause the valve body to be in a state of high temperature and high pressure for a long time, resulting in cracking.

All kinds of reasons, improper selection and use of valve body materials, improper welding process, etc., will cause valve body cracking. In order to avoid valve body cracking, it is necessary to strictly control the selection of valve body materials, strictly operate the welding technology and process, and use the valve products reasonably in the environment with appropriate temperature and pressure.