Each piece of equipment and appliance should be provided with a shut-off valve which is separate from the appliance to permit maintenance, repair, replacement and temporary disconnection. The shut-off valve should be adjacent to the appliance, no farther away than 6 feet, conspicuously located, and within reach.
Shut-off valves should not be located in concealed locations and shall have access provided. They should be easily located and operated in the event of an emergency. For example, a gas shut-off valve for an appliance on the first floor should not be located in the basement. There is an exception for decorative appliances.
A shut-off valve should be installed ahead of any flexible (semi-rigid) appliance fuel connector. It should not be less than the nominal size of the connector.
Gas outlets that do not connect to appliances should be capped gas-tight in case the shut-off valve opens or fails.
Every gas meter should be equipped with a shut-off valve located on the supply-side of the meter. There should be a lockable valve located at the gas meter. www.nachi.org