What is a gas line pressure test?

A gas line pressure test checks whether a newly installed or modified gas piping system can hold pressure without leaking. The technician isolates the gas line and fills it with nitrogen (or sometimes compressed air at low pressure) to a specified test pressure, then watches for any drop in pressure over time. If the gauge holds steady, the line passes. If pressure drops, a leak exists somewhere in the line, fitting, or valve, and the technician must locate and repair it before the system can be used.

This procedure is required by the International Fuel Gas Code and local building codes in Aiken, SC before any gas appliance such as a water heater, furnace, or cooktop can be safely connected and operated. The test pressure typically ranges from 10 to 100 pounds per square inch (psi) depending on the system type and code requirements in your area. Testing protects both safety and efficiency by confirming that gas won't escape into walls, crawl spaces, or living areas, and that the system will operate at proper pressure.

Plumbers performing gas work are required to perform and document a pressure test before leaving a job. If you're having gas lines installed or repaired, your contractor should provide written proof that the test passed.