1.Valve Shell Strength Test Pressure
In American standards, the shell strength test pressure of a valve is typically based on the valve's pressure - temperature rating. For example, for a standard flanged steel valve with a rated pressure class (such as Class 150, Class 300, etc.), the test pressure is calculated according to the relevant ASME (American Society of Mechanical Engineers) standards. For a Class 150 valve, the shell test pressure is usually 1.5 times the rated pressure at a specific temperature.
2.Backseat Test Pressure
The backseat test pressure in American standards also depends on the valve type and its rated pressure. Generally, it is a fraction of the valve's rated pressure. For many common valves, the backseat test pressure is around 75% - 80% of the maximum allowable working pressure of the valve. The specific value is specified in the valve's design and test standards such as API (American Petroleum Institute) standards for certain types of industrial valves.
3.High - Pressure Seal Test Pressure
For high - pressure seal tests of valves in American standards, the test pressure is often related to the valve's rated pressure class. For example, in the case of a gate valve used in high - pressure oil and gas pipelines, the high - pressure seal test pressure can be 1.1 times the maximum allowable working pressure specified for the valve's pressure class. This is to ensure that the valve can effectively prevent internal leakage under high - pressure conditions.
4.Low - Pressure Seal Test Pressure
The low - pressure seal test pressure in American standards usually ranges from 0.5 to 0.6 times the maximum allowable working pressure of the valve. It is designed to check the valve's ability to seal under relatively low - pressure conditions. This is important for applications where even a small amount of leakage can cause problems, such as in some precision chemical processes or in systems where fluid conservation is critical.
