When installing a gas shutoff valve, the following materials and tools are needed: an adjustable wrench, soft cloth, a wire brush, gas-line seal tape, a gas appliance valve and gas-leak detection solution.
Disable the main gas supply
Contact your gas service provider to check for special regulations and instructions before turning off the gas supply. Turn off the gas at the main supply, which is often located near the meter. The gas meter and gas shutoff valve are typically located on the side or front of a building.
Prepare the pipe for installation
Clean the threads on the gas pipe using a small wire brush. Wipe the threads with a soft cloth. To avoid personal injury or property damage, do not allow strong cleaning solutions or chemicals, such as acids, solvent solder fluxes, bleach or dish detergent, to contact the connector.
Install the gas valve
Wrap three layers of gas-line seal tape around the gas pipe's thread. Twist the gas appliance valve onto the gas pipe, and tighten it with an adjustable wrench.
Test the joint for leaks
Apply a liberal amount of gas-leak detection solution to the gas connection to test for leaks. Turn on the gas, and diligently look for any bubbles around the connection. If bubbles appear, turn off the gas, and re-tighten the valve.