Due to the wide range of valve applications, various media, and different corrosion conditions, the service life of valves is not regulated from national standards to industry standards. In 1980, the Ministry of Machinery Industry aimed to improve the quality of machinery industry products and cooperate with the whole country. High-quality product appraisal, formulated the "Valve Industry Product Quality Grading Regulations", among whichgate,CutoffThe first-class and high-quality products of the company stipulate the life test requirements; for example, Dn≤200～400 high-medium pressure valve first-class scratch resistance is 2000 times, and the excellent product is 4000 times.
There are two ways to express the service life of foreign valves: one is the service life, and the other is the number of times of switching.
Due to the particularity of nuclear power plants, all countries have stipulated the service life of nuclear power valves; valves used in the nuclear industry are expressed in terms of service life, and the general service life is 30-40 years. The United States and Germany nuclear power valves guarantee 40 years, and the United Kingdom 30 years. Japan 30-40 years.
Generally, the service life of a valve is expressed by the number of openings and closings. Due to the difference in use conditions and different test methods, the number of openings and closings does not necessarily indicate the life of the valve.Only when the working conditions are the same, the use or test methods are the same, and the number of switches is large or the use time is long, can the service life be considered long.