What must leak testing prove for underground piping?

For underground piping, leak testing is crucial to ensure the integrity and safety of the system. The requirement for the leak test to be conducted at a pressure equal to at least the normal operating pressure is based on the need to simulate actual working conditions while also providing a safety margin. This method ensures that any potential leaks can be detected since the test pressure will stress the joints and connections in the system similarly to how they would experience stress during regular operation.

Testing at the normal operating pressure also helps in identifying weaknesses or flaws that could lead to leaks during regular use. This is especially important in systems conveying compressed natural gas, where any failure could have significant safety implications. By confirming the system can hold the normal operating pressure without any loss, operators can be assured of the system's reliability and integrity in practical situations.

The other pressure requirements do not provide the same level of assurance as testing at normal operating pressure. Testing at half the operating pressure may not adequately identify vulnerabilities since it does not replicate the pressure levels that the system will experience during operation. Maximum possible pressure tests can be unnecessarily strenuous and risky, possibly leading to equipment damage. A requirement of no pressure loss alone does not specify the conditions under which the test should be conducted, making it less practical for identifying leaks