Section 8.2.1/Gas Piping Pressure Testing
NFPA 54 Section 8.2 covers pressure testing of gas piping including test medium, 3 psig minimum pressure, and 10-minute hold.
Gas piping systems must be pressure tested before being placed in service. The test must use air, nitrogen, carbon dioxide, or an inert gas (never fuel gas for testing). The test pressure must be at least 1.5 times the proposed maximum working pressure but not less than 3 psig (for systems operating below 14 inches water column). The test duration is a minimum of 10 minutes during which the pressure must not drop. All joints and connections must be accessible for inspection during the test. After a satisfactory test, the system must be purged of air before introducing fuel gas.
Why this section exists
A gas leak inside a building creates an explosion and fire hazard. Pressure testing verifies that every joint, fitting, valve, and connection in the gas piping system is leak-tight before fuel gas is introduced. The test pressure (1.5 times working pressure or 3 psig minimum) stresses the system beyond its normal operating condition to reveal marginal joints that might develop leaks over time. The 10-minute hold period allows time for even small leaks to register as a pressure drop on the test gauge.
What plan reviewers look for
Plan reviewers check the specifications for the pressure test requirement, test medium (air or inert gas, never fuel gas), test pressure (3 psig minimum or 1.5 times working pressure), and hold duration (10 minutes minimum). They verify the test is specified before concealment (all joints must be accessible during testing). For high-pressure systems (above 14 inches water column), they check that the test pressure matches 1.5 times the working pressure.