Extra Requirement: Cryogenic Pressure Testing
- Greg
- Jun 23
- 1 min read
The cryogenic service valve is being allowed to naturally warm up after completing the low-temperature pressure tests.
Cryogenic valves are designed for extreme conditions, and their testing process reflects that. Before they’re approved for service, these valves must prove their reliability through a series of rigorous steps—starting at room temperature and ending in liquid nitrogen at -196°C.
The process begins with standard ambient pressure tests, including shell and seal tests. These confirm the valve's basic structural integrity and sealing performance under normal conditions. Only after passing these tests does the valve move to the cryogenic stage.
Cooled with liquid nitrogen, the valve is brought to its operational temperature. At this point, two key tests are performed:
Body Leak Test – Helium gas is introduced at working pressure, and a helium leak spectrometer is used to detect any leaks through the body or bonnet. This method offers high sensitivity, capable of identifying even microscopic flaws.
Seal Test – While still at cryogenic temperature, the valve’s closed seal is tested using a leakage detector. The measured leak rate must meet the acceptable limits set by the applicable standard.
These procedures may vary slightly depending on the destination country and the relevant standard. Each defines its own criteria for testing procedure, test media, and test durations.
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