Before supplying gas under pressure into any piping, all opening and outlets from which gas can escape shall be closed.
Check for leakage
No match, flames or other sources of ignition shall be used to check foe gas leakage from meters, piping or appliance. Checking for gas leakage with soap and water solution shall be recommended. Artificial illumination used in connection with a search for gas leakage shall be restricted to battery operated flashlights (preferably of the safety type) or approved safety lamps. in searching for leaks, electric switches should not be operated. If electric lights are already turned, they should not be turned off. An individual shall not work alone in any situation where practice desires that two or more persons are necessary to carry out the work safely. Smoking is strictly prohibited.
Checking for leakage with Meter
Immediately after supplying gas into the piping, the system shall be checked to ascertain that no gas is escaping. This may be checked by carefully watching the test the test dial of the meter to determine whether the gas is flowing through the meter. Under no circumstances shall a leakage test be performed using a gas meter without ascertaining the operability of the meter immediately prior to such test. The details of installation of gas pipes are described in previous post.
Checking of leakage not using a Meter
This can be performed by attaching to an appliance orifice, a manometer or equivalent device(gauge) so that it can be read in increments of 2.5 mm water column and momentarily turning on the gas supply and observing the gauging device for pressure drop with gas supply shutoff. No drop in pressure shall occur during a period of 3 minutes thereafter.
When leakage is indicated
If the meter test hand moves or a pressure drop on the gauge occurs, all appliances or outlets-supplied through the systems shall be checked to ensure that they are shut off and do not leak. If they are shut off firmly there is a leak in the piping system. The gas supply shall be shut off until the necessary repairs have been made, after which the test specified above shall be repeated.