14.1 IFGC Scope, Gas Types & Piping Materials

Fuel supply is 10 percent of the M2 exam: Fuel Supply Installation & Sizing 8 percent and Fuel System Connections 2 percent. Almost every item is 2024 IFGC Chapter 4, with Chapter 1 for scope, Chapter 2 for the point of delivery, and Section 310 for CSST bonding. Do not reach for IMC Chapter 13 oil piping or IMC hydronic tables when the fuel is natural gas or LP-gas.

IFGC versus IMC

2024 IFGC 101.2 applies the Fuel Gas Code to fuel-gas piping systems, fuel-gas appliances, gaseous hydrogen systems, and related accessories. 101.2.3 covers natural-gas piping at 125 psig or less and LP-gas piping at 20 psig or less (except as 402.7 allows), from the point of delivery to the outlet of the appliance shutoff valves. 101.2.4 adds gas-appliance installation, combustion and ventilation air, venting, and the connections to the piping. 101.2.6 is the handoff you must recite: mechanical systems that operate with fuels other than fuel gas are regulated by the International Mechanical Code. Oil boilers, electric heaters, and refrigeration machinery rooms stay in the IMC. A gas-fired rooftop, a gas water heater, and the black-iron or CSST that feeds them stay in the IFGC.

Venting of those gas appliances is IFGC Chapter 5, not IMC Chapter 8. After you pass the fuel pipe, finish the stack at vent terminations. A gas water heater is an IFGC appliance (624) whose T&P pipe is still IPC work — but the fuel pipe, sediment trap, and connector are this chapter.

401.1 repeats the Chapter 4 scope: design, installation, modification, and maintenance of piping systems from the point of delivery to the appliance connections, including materials, fabrication, testing, inspection, operation, and maintenance. 401.2 sends LP-gas storage to the International Fire Code and NFPA 58. The tank setbacks and container valves are not invented from Chapter 4.

Point of delivery and two gases

Point of delivery (IFGC Chapter 2) is the line where the serving gas supplier’s work ends and the IFGC piping system begins.

• Natural gas: the outlet of the service meter assembly, or the outlet of the service regulator or service shutoff valve where a meter is not provided. A system shutoff valve installed after the meter outlet is downstream of the point of delivery.
• Undiluted LP-gas: the outlet of the service pressure regulator, exclusive of line gas regulators.

You size and inspect from that point. Utility piping on the inlet side of the meter is not your Chapter 4 system (101.2.5 Item 16), except that utility piping inside a building still takes IBC structural and fire-protection rules (401.1.1).

Natural gas and undiluted propane are not interchangeable tables. Natural-gas capacity tables (402.4(1) through 402.4(24)) assume specific gravity 0.60 and report cubic feet per hour. Undiluted-propane tables (402.4(25) through 402.4(37)) assume specific gravity 1.50 and report thousands of Btu per hour. 402.4’s equation factors are Cr = 0.6094 and Y = 0.9992 for natural gas, and Cr = 1.2462 and Y = 0.9910 for undiluted propane. 301.7 requires the appliance to be designed for the fuel that is supplied; 301.7.1 forbids converting an appliance to a different fuel gas except where complete conversion instructions come from the installation instructions, the serving gas supplier, or the manufacturer. A natural-gas tankless piped with propane and no listed conversion kit is an unlisted appliance, not a “close enough” orifice swap.

Metallic pipe, CSST, copper, and PE

403.3.1: Cast-iron pipe shall not be used. That is a complete sentence. Cast-iron fittings are still allowed under 403.9.5 with tight limits; the pipe itself is banned.

403.3.2: Steel, stainless steel, and wrought-iron pipe shall be not lighter than Schedule 10 and shall meet ASME B36.10M plus ASTM A53/A53M, A106, or A312. The exam favorite is Schedule 40 black steel because 403.9.1 lets Schedule 40 and heavier joints be threaded, flanged, brazed, welded, or press-connected (ANSI LC-4/CSA 6.32). Pipe lighter than Schedule 40 shall not be threaded — only press-connect, flanges, brazing, or welding.

403.4.5: CSST shall be listed to ANSI LC 1/CSA 6.26. 404.2 requires installation to the approval, the listing, the manufacturer’s instructions, and this code. 401.5 sends CSST identification to that same ANSI LC 1 standard. 310.2 is the bonding rule for CSST that is not listed with an arc-resistant jacket: the CSST system, and any piping system that contains one or more segments of that CSST, shall be electrically continuous and bonded to the electrical-service grounding electrode system (or the lightning-protection grounding electrode system where provided). 310.2.1 connects the jumper to a metallic pipe, pipe fitting, or CSST fitting. 310.2.2: jumper not smaller than 6 AWG copper or equivalent. 310.2.3: jumper length not more than 75 feet. 310.2.4 sends the connection method to NFPA 70 — do not invent an article number the IFGC does not print. 310.3 treats arc-resistant-jacketed CSST as bonded when it is connected to appliances that are connected to the equipment grounding conductor, the same way 310.1 treats ordinary steel pipe. If any segment in the system is ordinary CSST, 310.2 applies to the whole system.

403.3.3 / 403.4.3: Copper and copper-alloy pipe and tubing shall not be used if the gas contains more than an average of 0.3 grains of hydrogen sulfide per 100 standard cubic feet. Tubing shall be Type K or L (ASTM B88 or B280). Threaded copper, copper-alloy, and aluminum-alloy pipe shall not be used with gases corrosive to those materials. 403.3.4 bans aluminum-alloy pipe outdoors and underground.

403.5: Polyethylene plastic pipe, tubing, and fittings that supply fuel gas shall conform to ASTM D2513 and shall be marked “Gas” and “ASTM D2513.” Polyamide shall conform to ASTM F2945 and be marked “Gas.” PVC and CPVC shall not be used to supply fuel gas. 403.5.2 sends plastic in undiluted LP-gas systems to NFPA 58. 404.17.1: plastic pipe shall be installed outdoors underground only, shall not be used within or under a building or slab, and shall not operate above 100 psig (natural gas) or 30 psig (LP-gas), except anodeless or service-head risers, a wall-head adapter inserting the plastic into indoor metallic pipe, or PE under an outdoor patio/walk/driveway that still meets the 12-inch burial depth in 404.12. 404.17.3: a yellow insulated copper tracer, not smaller than 18 AWG, suitable for direct burial, adjacent to underground nonmetallic piping, accessible or terminating above grade at each end.

Joints, fittings, and what is prohibited

403.8: metallic threads are taper pipe threads (ASME B1.20.1). 403.8.3: use a nonhardening thread joint sealant that is resistant to the gas and compatible with the pipe and fittings. 403.8.2 / Table 403.8.2 set field-thread length: 1/2- and 3/4-inch pipe get about 3/4 inch of thread and 10 threads; 1-inch gets 7/8 inch and 10 threads. Damaged or stripped threads are scrap (403.8.1). Visible defects are not repaired — the piece is replaced (403.6).

403.9.1 is the joint menu already cited. Brazing filler on nonferrous pipe melts above 1,000°F and contains not more than 0.05 percent phosphorus. 404.5 limits concealed fittings to threaded elbows, tees, couplings, plugs and caps; brazed fittings; welded fittings; and fittings listed to ANSI LC-1/CSA 6.26 or ANSI LC-4/CSA 6.32. A concealed union or an unlisted compression coupling in a wall fails 404.5.

403.9.5 metallic fittings: threaded fittings larger than 4 inches shall not be used. Cast-iron bushings shall not be used. Cast-iron fittings 4 inches and larger shall not be used indoors except where approved; 6 inches and larger shall not be used except where approved. Used pipe, fittings, and valves may be reused only where they are free of foreign materials and have been ascertained to be adequate for the service (403.2) — “we pulled it from the last job” is not that finding.

401.5 identification: for other than steel pipe and CSST, exposed piping shall have a yellow label marked “Gas” in black letters at intervals not exceeding 5 feet, except piping in the same room as the appliance served.

404.11: steel pipe or tubing exposed to corrosive action, including soil and moisture, shall be protected. 404.11.2 underground options are corrosion-resistant material, a factory-applied electrically insulating coating with coated joints, or a monitored cathodic-protection system. Bare black steel in a trench is the classic field fail.

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