Gas Line Pressure Testing in Spartanburg, SC

The International Fuel Gas Code sets the minimum in section 406. New piping is tested at no less than one and a half times the proposed working pressure, and never less than 3 psig, for at least 10 minutes, with no drop on the gauge. For a typical house running at a fraction of a pound, that means the 3 psig floor governs.

Those are minimums, and inspectors are allowed to ask for more. Spartanburg County's residential inspection requirements, for example, call for a 10 psi air test on gas lines at the meter release inspection, and underground gas piping is tested before it is backfilled. We set the test to whatever the inspecting office for your address requires, and that is usually higher than the code floor.

The test medium is air or an inert gas such as nitrogen. It is never oxygen, and never the fuel gas itself. The gauge has to suit the test: the code limits how coarse the scale can be relative to the test pressure, because a big dial gauge cannot show a small drop on a low-pressure test.

Gas valves on furnaces, water heaters, ranges and log sets are built for inches of water column, not pounds per square inch. Put 10 psi against one and you can damage the valve or the regulator inside it. So before a test, every appliance is either disconnected and the outlet capped, or isolated behind its closed shutoff valve where the code allows it.

The same goes for line regulators on 2 psi systems and the second-stage regulator on propane. They are isolated from the test or tested separately. Getting this step right is the difference between a clean test and an afternoon spent replacing a gas valve.

Home inspectors in the Upstate commonly note gas items: CSST that does not appear to be bonded, a missing sediment trap at the furnace, a flexible connector running through a wall, an uncapped stub where an appliance used to be, or a faint gas odor near the meter. A buyer's agent may then ask for the gas piping to be evaluated or tested.

A pressure test answers the leak question with a number. We isolate the appliances, test the whole system, and write down the test pressure, duration and result. If it fails, we find the leak. If we see code items along the way, like a missing cap or an unbonded run, we list them separately so the buyer and seller can see which items are leaks and which are fixes.

Because the gas has to be shut off for the test, every pilot in the house goes out. We relight and check each appliance afterward, so the seller is not left with cold water on closing day.

When a utility technician finds a leak or an unsafe condition, they may shut off and lock the meter, or tag the appliance or piping as unsafe to use. That tag stays until the problem is repaired. The utility may require a successful pressure test, and in some cases a city or county inspection, before they will turn the meter back on.

The order of operations matters. We find and repair the leak, test the piping to the required pressure and duration, and get any needed inspection released. The utility then restores service and relights on their schedule, or we relight once they have turned the gas on, depending on how they handle it in your area.

Vacant houses and homes where the gas has been off for a long time follow a similar path. Before gas is reintroduced into piping nobody has checked in a while, a test is the sensible first step, and the utility may ask for one.

A failed test is information, not a disaster. We hold the pressure on the line and work outward with leak-detection solution on fittings, valves and unions, splitting the system into sections if needed to narrow it down. Common culprits are old unions, valves on abandoned appliance stubs, and joints in hidden spaces that were disturbed during a remodel.

Temperature can also move a gauge. Air in a line that runs through a hot attic or along a sunny exterior wall expands and contracts as the temperature changes, so we account for it on outdoor and attic runs and retest rather than guessing. A line passes when it holds, not when it is close.