Referenced Standards and Fuel Gas Piping
Referenced standards
The plumbing code relies on referenced standards for materials, testing, and installation. Examples include ASTM standards for pipe and fittings, ASME standards for valves and boilers, ASSE standards for backflow preventers, CSA standards for gas appliances, NSF standards for drinking water components, and UL standards for controls. The edition referenced by the adopted code governs; a newer standard is not automatically acceptable. Materials must be listed and labeled by an approved agency.
Fuel gas piping
Fuel gas piping is governed by the International Fuel Gas Code or NFPA 54 as adopted. Pipe materials include black steel, corrugated stainless steel tubing, and polyethylene for underground service. Each appliance needs a shutoff valve, a union or flanged connection, and a sediment trap. Gas piping must be supported, protected against corrosion, bonded, and tested before use. Sizing uses the appliance input in BTU per hour, the gas heating value, the longest length, and the pressure drop table.
Worked example
A 100,000 BTU/h furnace uses natural gas with a heating value of about 1,000 BTU per cubic foot, so it needs about 100 cubic feet per hour. The installer must use the longest-length method from the gas table, not the branch length, to select the pipe size. A short branch off a long run may still be undersized.
Traps
Do not install a sediment trap after the appliance regulator in the wrong orientation. Do not use plumbing drain fittings for gas. Do not omit bonding or testing. Do not assume a material is approved because it is sold for gas.