What is the maximum pressure that natural gas can pass through a half-inch pipe into your appliances?

Answer 1

4 to 8 oz. Natural gas entering the building is reduced to 10" water column by the regulator on the gas meter, and is further reduced to 3.5" w.c. by the individual appliances. The size ( in this case you mentioned 1/2 inch ) does not matter. What does matter is the design, installation, and testing. The gas purveyor can provide regulators at the meter that reduce the pressure entering the structure to 1/2 pound, 2 pounds, and 5 pounds, that I know of. Other pressures might be available. The system would have to be installed, tested, and inspected at the test pressures required by the administrative authority. It would also have to meet any other code requirements, such as type of material (pipe and fittings), type of joint for the installed size (welded, threaded, etc.), hangers (and spacing of), isolation, etc. Here in Oregon we are required to test a gas system at 30 times the regulator setting. Therefore a 1/2 pound system is tested at 15#, a 2 pound system is tested at 60 pounds, and so on. The advantage to piping a structure with a higher pressure system is that pipe sizing can be correspondingly lower, especially beneficial in long runs in commercial structures. The drawback is, if a pressure above 1/2 pound is used, an additional pressure regulator is necessary at each appliance. You also need to consider the cubic feet per minute so you can establish pipe sizing. even at higher pressure for some appliances especially furnaces you might possibly run a one inch or larger pipe if you have other gas appliances in your building.