5.6 Gas Piping Materials, Installation, Testing & Appliance Connections (IFGC 403–411, 624)

Gas Piping Materials, Installation, Testing & Appliance Connections (IFGC 403–411, 624)

Section 5.4 sized the pipe, and Section 5.5 vented the appliance. This section covers what a plans examiner checks between them: pipe materials, routing, protection, testing, valves and the final connection to a gas water heater. Most of it comes from IFGC Chapter 4, with water heater rules in IFGC 624.

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Gas Water Heaters (IFGC 624)

• Listing (624.1): Gas water heaters are listed to ANSI Z21.10.1/CSA 4.1 (storage, 75,000 Btu/h or less) or ANSI Z21.10.3/CSA 4.3 (larger and instantaneous) and installed per the manufacturer's instructions. Water heaters using fuels other than gas fall under the IMC.
• IPC coordination (624.1.1): Sizing, relief valves, drain pans and scald protection follow the IPC (see Sections 5.2 and 5.3).
• Combination space heating (624.2): A water heater supplying both potable water and space heating must be listed and labeled for both uses and installed per the IPC.

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Approved and Prohibited Materials (IFGC 403)

Threads are taper pipe threads per ASME B1.20.1. Damaged threads may not be used (403.8), and pipe with visible defects is replaced, not repaired (403.6).

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Routing and Protection (IFGC 404)

• Prohibited locations (404.3): Gas piping may not run in or through a ducted supply, return or exhaust, a clothes chute, chimney or gas vent, dumbwaiter or elevator shaft. Piping may not pass through a townhouse unit other than the one it serves.
• Solid walls (404.4): Concealed piping in solid walls or partitions must be in a chase or casing.
• Concealed fittings (404.5): Only threaded elbows, tees, couplings, plugs and caps, brazed or welded fittings, or fittings listed to ANSI LC-1 or LC-4. Unions are not allowed in concealed locations.
• Foundation walls (404.6): Gas piping may not penetrate a foundation wall below grade. It enters above grade, and the annular space is sealed.
• Shield plates (404.7): Concealed piping less than 1-1/2 inches from the face of framing gets steel shield plates of at least 0.0575 inch (No. 16 gage). The plates cover the framing and extend 4 inches each side. Black and galvanized steel pipe are exempt.
• Burial depth (404.12): At least 12 inches below grade, or 8 inches for individual lines to outdoor lights, grills and similar appliances where approved and protected.
• Plastic pipe (404.17): Plastic pipe is used outdoors underground only, never within or under a building or slab, at 100 psig or less for natural gas (30 psig for LP-gas). Exceptions cover anodeless risers, wall head adapters and outdoor patio or driveway slabs. Metal-to-plastic transitions underground use ASTM D2513 Category I or ASTM F1973 fittings. A yellow insulated tracer wire of at least 18 AWG runs alongside the pipe.

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CSST Bonding (IFGC 310.2)

CSST not listed with an arc-resistant jacket must be bonded to the electrical service grounding electrode system. The bonding jumper is at least 6 AWG copper, no longer than 75 feet, and attached to a metallic pipe or fitting, not to the corrugated tubing.

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Pressure Testing (IFGC 406.4)

• Test pressure (406.4.1): At least 1-1/2 times the maximum working pressure, and never less than 3 psig.
• Duration (406.4.2): At least 1/2 hour per 500 cubic feet of pipe volume. Systems under 10 cubic feet, or in a single-family dwelling, are tested for at least 10 minutes. No test needs to exceed 24 hours.
• Gauges (406.4): A mechanical gauge's full scale may not exceed five times the test pressure.
• Medium (406.2): Air, nitrogen, carbon dioxide or an inert gas. Oxygen is never used.

Example: A 2-psig elevated-pressure system is tested at $1.5 \times 2 = 3$ psig. A 5-psig system is tested at $7.5$ psig, with a gauge no larger than 37.5 psig full scale.

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Sediment Traps, Shutoff Valves and Connectors

• Sediment trap (408.4): Where the appliance has no built-in sediment trap, one is installed downstream of the shutoff valve, as close to the appliance inlet as practical. It is a tee with a capped nipple in the bottom outlet. Water heaters need one; ranges, clothes dryers, gas fireplaces and outdoor grills do not.
• Wet gas slope (408.1): Piping for other than dry gas slopes at least 1/4 inch in 15 feet.
• Appliance shutoff (409.5.1): The valve is in the same room, within 6 feet of the appliance and upstream of the union, connector or quick-disconnect. A valve at a manifold may be up to 50 feet away if it has ready access and is identified (409.5.3).
• Prohibited valve locations (409.1.2): Shutoff valves may not be concealed or placed in furnace plenums. A meter has a valve on its supply side (409.2).
• Connection methods (411.1): Rigid metallic pipe, CSST, semirigid tubing no longer than 6 feet in the same room, or listed connectors per ANSI Z21.24 located in the same room.
• Connector limits (411.1.3): At most 6 feet long, one per appliance, never concealed in or run through walls, floors, ceilings or appliance housings (with listed exceptions). The shutoff valve is at least the connector's nominal size.
• Unions (411.1.6): Rigid pipe connections need an accessible union within 6 feet of the appliance.

      GAS WATER HEATER CONNECTION SEQUENCE (IFGC 408.4, 409.5, 411)

   Supply ──► SHUTOFF VALVE ──► UNION or CONNECTOR ──► TEE ──► APPLIANCE
              (same room,        (connector 6 ft max,   │      INLET
               within 6 ft)       one per appliance)    ▼
                                                   Capped nipple
                                                   (sediment trap)

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Plan Reviewer Verification Checklist: Gas Piping Installation

• Materials: No cast iron, PVC or CPVC; copper only where gas sulfur content permits; CSST is listed (403).
• Routing: Nothing in ducts, chimneys, shafts or chutes; no below-grade foundation penetrations; concealed fittings limited (404).
• Plastic Pipe: Outdoors underground only, with a tracer wire and listed transitions (404.17).
• CSST Bonding: A 6 AWG jumper of 75 feet or less, unless arc-resistant CSST is used (310.2).
• Test: At least 1.5 times working pressure and at least 3 psig, for the required duration (406.4).
• Appliance Connection: Shutoff valve in the same room within 6 feet, a sediment trap, a connector of 6 feet or less, and no wall penetrations (408 to 411).