Gas piping is the method of conveying a fossil fuel from a natural gas well or a storage tank to your appliances such as furnaces, ranges, water heaters and dryers. The gas in the pipework is pumped at high pressure and reduced in pressure before your gas meter and again at your appliance. Typical gas pressure inside a residence is less than 1 pound and is measured in inches of water column. If you were to completely sever a pipe in your home the sound of the escaping gas would make a sound similar to someone exhaling a sigh of relief. Gas piping is strictly regulated under the Gas Coded Book (B149A). Gas meters measure the amount of gas used at a particular building for billing by the utility company. The gas meter is by law, to be checked every 10 years under the weights and measures act for accuracy. The meters use to measure in cubic feet of gas per hour (CFH) of consumption and are mostly now in cubic meters per hour (CMH). Special licensing is required for those technicians that do underground gas piping (in plastic) for connecting onto the main street service or for installing a pipe to a pool heater in someone's backyard. The newest "approved" gas line is made of flexible stainless steel with a vinyl coating to protect the pipe. This type of piping permits a single piece of material to connect an appliance from the farthest corner of a house to the other. All gas lines have to be supported and /or protected. There are very specific tables in the Gas Code Book for determining the spacing of supports, and how they are fastened to the pipe. The traditional material for gas lines is Schedule 40, Black Iron Pipe. The "schedule 40" refers to the thickness of the wall of the pipe. Copper is also approved for some applications. All gas piping has to be identified with yellow paint or tape banding, but must be completely painted if on the exterior of a building and exposed to the elements.

Pipework can be connected using threaded fittings made of the same material as the pipe, compression fittings or even welded using electric arc. Each appliance must have a shut off valve for safety and service. All threaded fittings require an approved sealant compound on the joints to prevent leaks. All new gas piping has to be pressure tested with nitrogen gas for a specific length of time and a specific pressure before it can be opened to the gas supply. The technician has to sign off that the test was successful along with all the information about the piping system and affix an official tag to the pipe with his /her name and license number.

Gas licensing of a technician is achieved through a registered apprenticeship program with the Ministry and there are different levels of certification. A Fitter III license is the first step and the easiest to achieve and essentially allows you to carry your bosses' toolkit. A Gas Fitter II license permits service and installation on appliances up to and including 400,000 BTU's. A Gas Fitter I license permits the technician to install and service very large equipment in the millions of BTU's. The fourth license is a "P" for underground pipework. A welder with certification on welding pressure vessels is required for welding gas piping. The gas licensing also includes certification on Propane gas. A properly licensed welder can install a new branch line on an active gas line without even turning the gas off. This is called a "Hot Tap" and is completely safe to perform.

Please refer to the sections in "Learn About" on Gas Leaks, What to do if you smell gas, Repairing gas leaks and Restarting appliances.