Solutions to Failures of Valves

A valve is a control component in the fluid delivery system, which has the functions of cutting off and adjusting the fluid, preventing the reverse fluid, stabilizing the pressure, dispersing the fluid, overflowing and relieving the pressure. There are many types and specifications of valves such as globe valves and ball valves with simple structures, as well as complex valves suitable for automatic control systems. With the increasing manufacturing demand and the improvement of industrial automation technology, people pay more and more attention to failure analysis of valves and their solutions in order to ensure smooth production and no accidents, especially in aerospace, nuclear power, thermal power, nuclear power, high-temperature and high-pressure fields. A valve plays an important role in industrial production. Therefore, studying the failures and causes of valves are very important for practical applications such as the stress, strength, and fatigue of the valve.
 
At present, many scholars have conducted a lot of research on the reliability analysis of the valve, part of which is from individual to the whole. Conduct a complete analysis of valves for specific environments and needs; study their failures and principles, and then expand to the overall field. Other people start from the basic theory. They first conduct a comprehensive design analysis of the reliability of valves from different ways such as strength and sealing, and then conduct test research for specific valves according to different situations. There is no complete specification for design guidance due to the variety of valves and complex working conditions. Therefore, according to the analysis of failure types of valves, the causes of different failures of valves and their solutions are talked about from the perspectives of materials, design, testing and manufacturing in this article.
 
Solutions to failures of valves 
Failures of valves such as blocking, breaking and leaking can be solved from the aspects of materials, design, tests and production.
 
(1) Materials
The material and its characteristics such as stress, strength and corrosion resistance in practical applications are the key factors to solve the problem of failures of valves and improve the reliability of the valve.
① Use advanced technology to develop composite materials.
②Heat treatment should be conducted for valves, pipe fittings and components to improve their performance and internal metal structure to improve the corrosion resistance and strength of the valve.
③Adopt advanced surface technology such as spray welding and cladding to improve the wear resistance and corrosion resistance of parts.
 
(2) Design
Use advanced dynamic simulation, parameter technology and finite element analysis methods to conduct the strength calculation and structural design of the product. In addition to special process requirements, environmental factors such as chemical corrosion, thermal stress corrosion, resonance, frequency and pressure fluctuations should also be considered. Stress limit calculations and fatigue performance analysis related to system operation and conversion of working conditions should be carried out.
 
(3) Tests and production
According to the requirements of characteristics and actual functions of valves, a test platform conforming to the valve's working environment is simulated and established. For some key valves, conduct tests for action and performance of valves under simulating actual operating conditions, and grasp their reliability under actual operating environmental conditions. Improve manufacturing process, manufacturing equipment of valves, and avoid material defects, strength reduction, and size deviation caused by poor manufacturing. The blocking of the valve is solved by adjusting the distance between the valve wedges.
 
Conclusion

(1) Through a summary of common failures of valves, analyze their causes and mechanisms.

(2) The research and development investment of new materials or composite high-impact materials should be increased, and advanced design methods should be used for the strength calculation and structural design of products, and improve the level of process and equipment manufacturing to improve the quality of valves.
(3) Establish reliability database and reliability analysis systems of valves to find and eliminate factors affecting reliability as early as possible in the early design stage.