ASME B31.3 does not permit the use of an “ASME Section V Pressure Change Test” as a substitute for the mandatory leak testing requirements (hydrostatic, pneumatic, or initial service leak test) defined in Chapter VI of the B31.3 Code.
Why It Cannot Be Used as a Substitute:
ASME B31.3 requires a 100% visual examination of all joints and connections for leakage during the pressure test. The Code does not provide a provision to replace this visual examination with pressure decay monitoring (pressure change testing). The primary purpose of a leak test under B31.3 is to verify the leak-tightness of all joints—including welds, flanges, and fittings—by direct visual inspection while the system is held at a specified pressure.
ASME Section V is an NDE (Nondestructive Examination) code, not a construction or testing code. It provides methods and procedures for performing examinations, but it does not dictate when or whether a specific test (such as a pressure change test) must be used for piping systems. The requirements for which test to apply and how it must be conducted are dictated by the referencing construction code, which in this case is ASME B31.3.
ASME B31.3 (Construction/Piping Code) sets the legal requirement that a leak test must be performed, defines the pressures (hydrostatic/pneumatic), and mandates the visual examination of all joints.
ASME Section V (NDE/Examination Code) provides the technical methodologies for various testing techniques. While Section V includes procedures for “Pressure Change” methods (often used for sensitive leak detection or vessel integrity), these are NDE methods for detecting leaks. They do not fulfill the B31.3 requirement for a pressure/leak test, which serves as a final proof of structural and joint integrity.
Exceptions and “Alternative Leak Tests”
If you are unable to perform a standard hydrostatic or pneumatic test, ASME B31.3 allows an Alternative Leak Test (Paragraph 345.9), but only with the owner’s approval.
This alternative must be a written, qualified procedure that includes:
A sensitive leak test (such as a helium mass spectrometer or bubble test).
A formal design review and analysis to ensure safety.
Compliance with specific requirements that mimic the safety and verification goals of the standard hydro/pneumatic tests.
Even in these alternative scenarios, the goal remains to ensure the integrity of the piping system, and you must strictly follow the procedural requirements set forth by the B31.3 Code rather than importing testing methods directly from Section V without that specific B31.3 authorization.