From the 2006 IFGC:
Section 101.2.4 Systems and equipment outside the scope.
This code shall not apply to the following:
1. Portable LP-gas equipment of all types that is not connected to a fixed
fuel piping system.
2. Installation of farm equipment such as brooders, dehydrators, dryers
and irrigation equipment.
3. Raw material (feedstock) applications except for piping to special
atmosphere generators.
4. Oxygen-fuel gas cutting and welding systems.
5. Industrial gas applications using gases such as acetylene and acetylenic
compounds, hydrogen, ammonia, carbon monoxide, oxygen and nitrogen.
6. Petroleum refineries, pipeline compressor or pumping stations, loading
terminals, compounding plants, refinery tank farms and natural gas
processing plants.
7. Integrated chemical plants or portions of such plants where flammable
or combustible liquids or gases are produced by, or used in, chemical
reactions.
8. LP-gas installations at utility gas plants.
9. Liquefied natural gas (LNG) installations.
10. Fuel gas piping in power and atomic energy plants.
11. Proprietary items of equipment, apparatus or instruments such as
gas-generating sets, compressors and calorimeters.
12. LP-gas equipment for vaporization, gas mixing and gas manufacturing.
13. Temporary LP-gas piping for buildings under construction or renovation
that is not to become part of the permanent piping system.
14. Installation of LP-gas systems for railroad switch heating.
15. Installation of hydrogen gas, LP-gas and compressed natural gas
(CNG) systems on vehicles.
16. Except as provided in Section 401.1.1, gas piping, meters, gas pressure
regulators and other appurtenances used by the serving gas supplier
in the distribution of gas, other than undiluted LP-gas.
17. Building design and construction, except as specified herein.
18. Piping systems for mixtures of gas and air within the flammable range
with an operating pressure greater than 10 psig (69 kPa gauge).
19. Portable fuel cell appliances that are neither connected to a fixed
piping system nor interconnected to a power grid.
It's up to the gas supplier to determine their location.
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