14.3 Installation, Supports, Testing, Valves, Connectors & LP-Gas

Installation is where a correctly sized Schedule 40 main still fails the inspection. Walk supports, concealment, drips, valves, connectors, the pressure test, the purge, and — on propane jobs — the two-stage regulators before you ever light a burner.

Supports, concealment, and sediment traps

407.2 requires hooks, straps, bands, brackets, hangers, or structural components that prevent vibration, anchor the pipe so appliances are not strained, and do not hang pipe from other pipe. Hangers conform to MSS SP-58 and are spaced per 415. 415.1: support intervals shall not exceed Table 415.1. CSST spacing is per the CSST manufacturer’s instructions, not Table 415.1.

Table 415.1 (2024):

A 1-inch black-iron basement main strapped every 12 feet fails the 8-foot row. A 1/2-inch drop hung 10 feet between hangers fails the 6-foot row.

404.3 prohibited locations: no piping in or through a ducted supply, return, or exhaust, or a clothes chute, chimney, gas vent, dumbwaiter, or elevator shaft. Piping downstream of the point of delivery shall not run through a townhouse unit it does not serve. 404.5 (already covered) limits concealed fittings. 404.7 protects concealed piping in light-frame assemblies: where the pipe is less than 1-1/2 inches from the face that will receive the membrane, install No. 16 gage (0.0575 inch) steel shield plates that cover the pipe and extend 4 inches beyond the framing member. Exception: black steel and galvanized steel pipe do not need those plates. CSST and copper in a stud bay almost always do. 404.12 burial depth is 12 inches below grade (individual outdoor appliances may use 404.12.1). 404.17 still keeps PE outdoors underground with the yellow tracer.

408.1: piping for other than dry gas slopes not less than 1/4 inch in 15 feet to prevent traps. 408.2: where wet gas exists, install a drip at any point where condensate could collect, and at the meter outlet, arranged so condensate shuts off gas before it runs back into the meter. 408.3: drips need ready access and shall not freeze. 408.4 sediment trap: where a sediment trap is not built into the appliance, install one downstream of the appliance shutoff valve, as close to the inlet as practical. The legal shop-built trap is a tee with a capped nipple of any length in the bottommost opening (Figure 408.4), or another approved device. Illuminating appliances, ranges, clothes dryers, decorative vented appliances for vented fireplaces, gas fireplaces, and outdoor grills need not have one. A commercial furnace, boiler, unit heater, or tankless water heater that arrived without an integral trap does. A missing drip leg on a rooftop unit is a 408.4 fail, not a “manufacturer will add it later” note.

Shutoff valves and appliance connectors

409.1.1 / Table 409.1.1 require an approved valve listed to the pressure: ANSI Z21.15/CSA 9.1 only up to 1/2 psig appliance shutoffs; ASME B16.44 covers higher ratings when labeled 2G or 5G; ASME B16.33 covers up to 125 psig. 409.1.2: shutoff valves are prohibited in concealed locations and furnace plenums. 409.1.3: locate them for access and protect them from damage. 409.4: a listed shutoff sits immediately ahead of each MP regulator. 409.7: a valve in a tubing system is supported independently of the tubing.

409.5.1 is the default appliance valve: same room as the appliance, within 6 feet, upstream of the union, connector, or quick-disconnect, and provided with access. Valves serving movable cooking appliances and clothes dryers are considered accessible behind those appliances. 409.5.2 allows a remote, permanently identified valve for vented decorative appliances and room heaters if it serves no other appliance. 409.5.3 allows a manifold valve within 50 feet, with ready access and permanent identification. In both remote cases, the piping from that valve to within 6 feet of the appliance is sized and installed as Chapter 4 piping — it is not a 6-foot flex.

411.1 is the connection menu: rigid metallic pipe; CSST per the manufacturer; semirigid metallic tubing not more than 6 feet and entirely in the same room; listed ANSI Z21.24/CSA 6.10 appliance connectors in the same room; listed quick-disconnects (Z21.41) and convenience outlets (Z21.90) used with listed connectors; listed outdoor connectors (Z21.75); listed outdoor hose (Z21.54) used only outdoors. 411.1.1: commercial cooking appliances on casters, and appliances moved for cleaning, take a Z21.69/CSA 6.16 connector plus the manufacturer’s restraining device. 411.1.3.1: a connector’s overall length shall not exceed 6 feet, measured along the centerline, and only one connector per appliance. Rigid metallic pipe used as the connection may exceed 6 feet if it is sized as part of the 402 system and the shutoff still meets 409.5. 411.1.3.2: the connector must have the capacity of the appliance. 411.1.3.3: connectors shall not be concealed within, or extended through, walls, floors, partitions, ceilings, or appliance housings. The useful exceptions are: Chapter 403 piping materials on a 409.5.2 / 409.5.3 remote-valve run; rigid steel through an appliance-housing opening; listed fireplace-insert grommets; and semirigid tubing or a listed connector through an appliance housing where protected against damage. A corrugated connector shoved through a cabinet side wall, a dryer closet partition, or a platform floor is the 2-percent “Fuel System Connections” item. 411.1.3.4: the shutoff ahead of the connector is not smaller than the connector. 411.1.6: rigid metallic connections get a union with access within 6 feet of the appliance.

Pressure test 406, purging, MP regulators, LP-gas

406.1: before acceptance and initial operation, visually inspect and pressure test. 406.2 test medium: air, nitrogen, carbon dioxide, or an inert gas. Oxygen shall not be used. 406.3: leave joints, including welds, exposed during the test (except previously tested concealed joints). 406.3.2 / 406.3.3: appliances and equipment that are not part of the test are disconnected or isolated with blanks, blinds, or caps; anything rated below the test pressure shall be disconnected and the outlets capped. Testing with a furnace, water heater, or rooftop still valved onto the system is a 406.3 fail. 406.4: measure with a manometer or a calibrated pressure-measuring device; isolate the pressure source; a mechanical gauge’s full scale shall be not greater than five times the test pressure.

406.4.1 Test pressure: not less than 1½ times the proposed maximum working pressure, but not less than 3 psig. Above 125 psig, do not produce a hoop stress over 50 percent of SMYS. 406.4.2 Test duration: not less than 1/2 hour for each 500 cubic feet of pipe volume or fraction thereof. A system with volume less than 10 cubic feet, or a system in a single-family dwelling, is not less than 10 minutes. Duration need not exceed 24 hours. The folklore “3 pounds for 10 minutes” is therefore the small-system / dwelling case of a minimum 3 psig test — it is not a blanket substitute for 1½ × working pressure on a 2 psi or 5 psi commercial main, and it is not 10 minutes on a large-volume piping system. 406.5: any unexplained gauge drop is a leak. 406.6.3 / 406.6.4: after gas is turned on, leak-check the system; do not place appliances in operation until the piping has been leak-checked, purged per 406.7, and the appliance connections leak-checked.

406.7.1 requires outdoor purging where design pressure is greater than 2 psig or the pipe meets Table 406.7.1.1 size-and-length criteria. 406.7.1.3 outdoor discharge: controlled with a shutoff; not less than 10 feet from ignition sources and building openings; not less than 25 feet from mechanical air intakes; continuously attended with a combustible-gas indicator; stop introducing fuel gas at 90 percent fuel gas by volume; evacuate persons within 10 feet of the discharge. 406.7.2 allows indoor or outdoor purging only where pressure is 2 psig or less and the pipe does not meet Table 406.7.1.1.

410.1: a line pressure regulator listed to ANSI Z21.80/CSA 6.22 is required where the appliance wants a lower pressure than the supply. Provide access and physical protection; outdoor regulators need an outdoor listing. 410.2 MP regulators (greater than 0.5 psig and not more than 5 psig down to a lower pressure): approved for the pressures; holds reduced pressure at lock-up; manufacturer-rated for the load; accessible; vented outdoors or equipped with a leak-limiting device if indoors; a capped tee between the upstream shutoff and the regulator (gauge port and sediment trap); a second capped tee not less than 10 pipe diameters downstream unless the appliance in the same room has a gas-control inlet test port; a union within 1 foot of either side when connected to rigid pipe. 410.3 vents a regulator directly outdoors, insect- and water-protected, unless it is labeled for an approved vent-limiting device.

LP-gas. 401.2 sends the storage system — tank location, container valves, relief orientation, and odorization — to the IFC and NFPA 58. Do not invent a setback the IFGC does not print. What Chapter 4 does print: point of delivery is the outlet of the service pressure regulator; first-stage (high-pressure) to second-stage pipe is Table 402.4(25) or (26) (10 psi class, thousands of Btu/h); second-stage to the appliance is Table 402.4(28) (11 in. w.c., 0.5 in. w.c. drop). Underground PE on LP follows 403.5.2 / NFPA 58 plus 404.17 (outdoor, buried, tracer, 30 psig plastic-pressure cap). Two-stage regulation is how those tables are meant to be used: a first-stage regulator at the tank, a second-stage or integral two-stage regulator before the building piping you size like any other low-pressure system. 402.7 Item 8 is the only indoor-pressure escape hatch for LP over 20 psi, and it still requires NFPA 58.

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