When is a pressure test not required according to ASME B31.3?

A pressure test is not required for non-pressurized piping systems according to ASME B31.3. This standard is designed to ensure the safe design and maintenance of piping systems. Non-pressurized systems, by definition, do not operate under pressure, and thus, the potential risks associated with pressure testing—such as leaks or failures—are not applicable. Therefore, a pressure test is unnecessary in this context because the system is not subject to stresses that a pressurized system would encounter.

In contrast, other piping systems, such as high-pressure ones or those that transport hazardous materials, typically require pressure tests to demonstrate their integrity and safety under operational conditions. Newly installed piping is also subject to testing to ensure that it meets safety and design specifications before being put into service.