Final answer:
Pressure testing for short residential natural gas piping systems below 2 psig should be conducted with air or an inert gas, adhering to local code specifications for pressure levels and test duration.
Step-by-step explanation:
For residential natural gas piping systems of 100 feet or less and with working pressure less than 2 psig, the piping or tubing shall be pressure tested using either air or an inert gas.
The standard procedure for this test involves filling the piping system with the testing medium (air or inert gas) and maintaining a specified test pressure, usually higher than the normal operating pressure, to check for leaks or weaknesses in the system.
The actual pressure value to be used for testing, as well as the duration of the test, are generally specified by local building codes or standards. It's important to ensure that all gas appliances are disconnected and that the test pressure does not exceed the system's rated maximum pressure.