Failures in Residual Pressure Valves (RPVs) can result from design and operational issues and stress corrosion cracking.
Fail-safe design ensures that in case of failures, the valves would still function at a basic level (i.e., open and close safely), and no unsafe gas release or ejection of parts occurs.
The Residual Pressure Device (RPD) housing threads are placed after the O-ring groove, which is the critical area.