What is limited in pneumatic testing?

• A. Corrosion
• B. Stored Energy Hazard
• C. Low Temperature
• D. High Temperature

Answer: (C)

In pneumatic testing the limit comes from temperature changes. The test uses a gas as the pressure medium, and as that gas is pressurized and then used to test the vessel, it expands and cools. This adiabatic cooling (and related temperature effects) can drive the gas and the metal surface to much lower temperatures, potentially approaching or dropping below the material’s safe operating range. That cooling is the controlling factor for how the test is planned, so low temperature is the limiting aspect.

Corrosion or high temperature aren’t the primary constraints of pneumatic testing itself, and while stored energy hazard is a safety concern with gas tests, the key limiting condition that governs the method is the risk of becoming too cold.