General Piping
15 Q · 38%
Allowable pressure drop and maximum operating pressure for indoor piping systemsApproved piping materials and tubing standards (steel, copper, CSST, polyethylene, aluminum)Piping joints, fittings, and connection methods (threaded, brazed, welded, press-connect, flared)Piping system installation requirements (prohibited locations, underground burial depth, protection from physical damage, corrosion protection)Pressure testing and inspection of gas piping (test medium, test pressure, test duration, leak detection)Purging procedures for gas piping systemsPipe support spacing, shutoff valves, drips, sediment traps, and flow controls
Pipe Sizing/Math
10 Q · 25%
Gas pipe sizing using longest length, branch length, and hybrid pressure methodsCalculating maximum gas demand in CFH from appliance BTU ratingsPressure drop allowances and equivalent lengths for fittings and valvesFitting allowances and end-to-end pipe length calculations for threaded, copper, and welded fittingsOffset, diagonal, rise, and run calculations using angle constants (45°, 60°, 22.5°)Grade, percent grade, drop, and run calculations for sloped pipingVolume, pressure, and capacity calculations for pipe and water systemsFraction, decimal, and unit conversion for pipe measurements
Chimney and Flues
5 Q · 12%
Appliance venting categories and type of venting system selectionVent and chimney termination height and location requirementsVent connector materials, sizing, slope, and clearancesMasonry chimney construction, lining, and inspection requirementsSizing Category I appliance venting systems using tablesGas vent types (Type B, BW, L) and installation requirementsDirect-vent and mechanical draft system termination clearancesDraft hoods, draft controls, and vent dampers
Combustion
5 Q · 12%
Combustion air requirements: indoor vs. outdoor methods (IFGC Section 304)Combustion air opening sizing and location (minimum free area per Btu/h)Flammability limits of natural gas and propane (ignition threshold percentages)Properties of natural gas vs. propane: weight relative to air, toxicity, odorizationDefinition and composition of combustion air, combustion products, and flue gasesCombustion chamber and burner definitions (main burner, power burner, induced-draft burner)Mechanical and engineered combustion air supply systems (Sections 304.8–304.9)Latent heat, heat transfer (Btu), and temperature conversion as applied to combustion processes
Appliances
5 Q · 12%
Listing, labeling, and testing standards for specific appliance typesInstallation clearances to combustible materials for heating appliancesClothes dryer exhaust duct requirements (materials, length, termination)Unvented room heater restrictions (input rating, oxygen-depletion safety shutoff, prohibited locations)Cooking appliance installation requirements and vertical clearancesWater heater installation and dual-use (space heating) requirementsSafety inspection procedures for existing appliance installations (gas leak checks, CO measurement thresholds, combustion air and vent draft testing)Flame safeguard and ignition device requirements for decorative and vented fireplace appliances
Maximum Operating Pressure – Indoor Piping 2018 IFGC, Page 32 (Section 402.7)
Per IFGC 2018 Section 402.7, gas piping inside buildings shall not exceed 5 psig unless special conditions are met such as welded joints or ventilated chase enclosure.
Minimum Burial Depth – Underground Gas Piping 2018 IFGC, Page 72 (Section 404.12)
Per IFGC 2018 Section 404.12, underground gas piping systems must be installed a minimum of 12 inches below grade (reduced to 8 inches only for individual lines to outdoor lights, grills, and similar appliances).
Minimum Pressure Test Duration – Single-Family Dwelling 2018 IFGC, Page 74 (Section 406.4.2)
Per IFGC 2018 Section 406.4.2, pressure tests on systems less than 10 cubic feet or in a single-family dwelling must last not less than 10 minutes.
Minimum Test Pressure 2018 IFGC, Page 74 (Section 406.4.1)
Per IFGC 2018 Section 406.4.1, the test pressure shall be not less than 1½ times the proposed maximum working pressure but never less than 3 psig regardless of design pressure.
Shield Plate Thickness – Piping Through Framing 2018 IFGC, Page 72 (Section 404.7.3)
Per IFGC 2018 Section 404.7.3, steel shield plates protecting gas piping located less than 1½ inches from a framing face must be not less than 0.0575 inch (No. 16 gage) thick.
Maximum Hole Diameter – Wood Joists 2018 IFGC, Page 20 (Section 302.3.2)
Per IFGC 2018 Section 302.3.2, holes bored through wood joists for gas piping shall not exceed one-third the joist depth and must remain at least 2 inches from top and bottom.
Maximum Hole Diameter – Exterior Bearing Wall Studs 2018 IFGC, Page 20 (Section 302.3.4)
Per IFGC 2018 Section 302.3.4, holes bored through wood studs in an exterior bearing wall shall not exceed 40 percent of the stud depth.
Prohibited Locations for Gas Piping/Appliances 2018 IFGC, Page 20 (Section 301.15)
Per IFGC 2018 Section 301.15, gas appliances, equipment, and systems shall not be located in an elevator shaft.
Purge Stop Concentration 2018 IFGC, Page 75 (Section 406.7.1.3)
Per IFGC 2018 Section 406.7.1.3, purging operations introducing fuel gas into large piping systems requiring outdoor discharge must stop when 90 percent fuel gas by volume is detected within the pipe.
Drip 2018 IFGC, Page 13 (Section 202, Definitions)
Per IFGC 2018 Section 202, a drip is a container placed at a low point in a gas piping system to collect condensate, from which the condensate is removable.
Piping System (defined scope) 2018 IFGC, Page 15 (Section 202, Definitions)
Per IFGC 2018 Section 202, a piping system comprises the fuel piping, valves, and fittings from the outlet of the point of delivery to the outlets of the appliance shutoff valves.
Pressure Drop IFGC Section 202
Per IFGC Section 202, pressure drop is the loss in pressure due to friction or obstruction in pipes, valves, fittings, regulators, and burners.
Brazing 2018 IFGC, Page 12 (Section 202, Definitions)
Per IFGC 2018 Section 202, brazing is a metal-joining process using a nonferrous filler metal with a melting point above 1,000°F but lower than that of the base metal; alloys must contain no more than 0.05% phosphorus.
Mechanical Joint 2018 IFGC, Page 15 (Section 202, Definitions)
Per IFGC 2018 Section 202, a mechanical joint is a gas-tight joint obtained by positive-holding mechanical construction including press-connect, flanged, threaded, flared, or compression joint types.
Acceptable Pressure Test Media 2018 IFGC, Page 74 (Section 406.2)
Per IFGC 2018 Section 406.2, acceptable test media are air, nitrogen, carbon dioxide, or inert gas; oxygen, natural gas, and acetylene are prohibited as test media.
Sediment Trap 2018 IFGC, Page 76 (Section 408.4)
Per IFGC 2018 Section 408.4, a sediment trap is a tee fitting with a capped nipple installed vertically in the bottommost opening, located downstream of the appliance shutoff valve to collect debris.
