What must be isolated before conducting pressure tests on piping systems?

Before conducting pressure tests on piping systems, it is essential to isolate the source of pressure. This step is crucial for ensuring safety and accuracy during the testing process. By isolating the source of pressure, you prevent any unintended release of pressure, which could lead to dangerous situations such as leaks or bursts. Isolating the pressure source also ensures that pressure measurements taken during the test reflect only the system being tested, without interference from other sources.

This practice also protects the integrity of the test itself, ensuring that the piping system is evaluated under controlled conditions, which is vital for diagnosing potential leaks or weaknesses accurately.