Exam Cheat Sheet · Quick Reference
ICC F33 Master Gas Pipe Fitter Exam (2015 IFGC)
National · Pearson Vue
Verified, not estimated. Every figure below is drawn from the official exam structure we maintain — question counts, passing standard and topic weighting. Practice questions are grounded in the source law with statute citations. We omit any figure we can't verify rather than guess at it.
Total questions
75
Passing score
70%
Exam time
180 min
Administered by
Pearson Vue
Format
Reference materials allowed
National State Portion 75 questions
General Requirements
37 Q · 49%
General Installation RequirementsCode Definitions and TermsPlan ReadingTestingMaterialsAppliance listing, labeling, and approval requirementsProhibited and restricted appliance locationsClearances to combustible construction and reduction methodsElectrical bonding and grounding of gas piping systemsAccess and service space requirements for appliancesPermits, inspections, and code enforcement authorityCondensate disposal requirements for fuel-burning appliances
+4 more
Water Heaters
4 Q · 5%
Installation of Water HeatersWater heaters used for combined space heating and potable hot water applicationsTesting standards for water heaters (ANSI Z21.10.1 and ANSI Z21.10.3)Water heater location: prohibited rooms and garage ignition-source elevationWater heater gas shutoff valveWater heater venting
Appliances and Equipment
11 Q · 15%
Requirements for Specific Appliances & EquipmentClearance requirements for specific appliancesClothes dryer exhaust duct installation and length limitsUnvented room heater restrictions and oxygen-depletion safety systemsVented wall furnace and floor furnace placement and access requirementsForced-air warm-air furnace return air prohibited sources and duct sizingAppliance listing standards and testing references (ANSI, NFPA, UL)Sauna heater location, combustion air, and heat/time controlsBoiler installation and control requirements
Fuel Supply System Sizing
4 Q · 5%
Service and Distribution Pipe SizingMaximum Gas Demand CalculationAllowable Pressure Drop and Minimum Supply PressurePipe Length Determination Methods (Longest Length, Branch Length, Hybrid Pressure)Low-Pressure vs. High-Pressure Sizing Equations and Table SelectionAltitude Adjustment for Gas Flow above 2,000 FeetMaximum Design Operating Pressure Limits and ExceptionsSizing for Additional Appliances and System ModificationsOverpressure Protection Device Requirements and Pressure Limitation SettingsGas Piping Installations
Combustion Air
10 Q · 13%
Combustion Air Source, Size of Duct/OpeningsIndoor Combustion Air Volume Requirements (Standard and Known ACH Methods)Combining Indoor Spaces for Combustion Air (Same Story and Different Stories)Outdoor Combustion Air Methods (Two-Opening and One-Opening)Combination Indoor and Outdoor Combustion AirMechanical Combustion Air Supply Requirements and Appliance InterlockLouvers, Grilles, and Screens (Net Free Area Calculations)Combustion Air Duct Construction and Installation RequirementsProtection of Combustion Air from Corrosive or Flammable Fumes
Chimneys and Vents
9 Q · 12%
Venting, Vent Connector, and ChimneysAppliance venting categories and vent type selection (Types B, BW, L, single-wall metal)Vent and chimney termination requirements and clearancesSizing of Category I appliance venting systems using IFGC tablesVent connector materials, installation, slope, length, and clearance requirementsDraft hoods, draft controls, and barometric draft regulatorsAppliances not required to be vented and aggregate input rating limitsGas vent termination locations relative to forced-air inlets, doors, and building openingsMasonry chimney inspection, lining, cleanout, and existing chimney requirementsChimneys and Vents
Key Distinctions
Longest length method (Section 402.4.1)vsBranch length method (Section 402.4.2)
The longest length method sizes every section of the system from the single table row for the meter-to-most-remote-outlet length, while the branch length method sizes each branch from its own total length measured from the meter (mains on the longest run still use the longest-run row).
IFGC Section 402.4.1, Longest Length Method; Table 402.4(2), Schedule 40 Metallic Pipe (natural gas, 0.5 in. w.c. drop)Outdoor combustion air opening communicating directly with outdoors or through a vertical ductvsOutdoor combustion air opening communicating through a horizontal duct
Vertical/direct openings require 1 square inch per 4,000 Btu/h, while horizontal ducts require 1 square inch per 2,000 Btu/h.
IFGC 2015 Section 304.6.1Appliance in a private garage (Section 305.5)vsAppliance in a public garage (Section 305.4)
Private garages require a minimum clearance of 6 feet above the floor (exception where protected from vehicle impact and installed per Section 305.3), while public garages require not less than 8 feet above the floor, and not less than 1 foot higher than the tallest vehicle garage door opening where vehicles can pass beneath.
IFGC 2015 Section 305.5Unvented room heater in a bedroom (Section 303.3, Item 4)vsUnvented room heater in a bathroom (Section 303.3, Item 3)
A single wall-mounted unvented room heater in a bedroom is limited to an input rating not greater than 10,000 Btu/h, whereas the bathroom limit is 6,000 Btu/h.
IFGC 2015 Section 303.3Low-heat (residential) appliancevsMedium-heat appliance
Under the Section 202 'Appliance Type' definitions, a low-heat appliance has flue-entrance combustion products at or below 1,000°F, while a medium-heat appliance exceeds 1,000°F but is not greater than 2,000°F.
IFGC 2015 Section 202 (definition of 'Appliance Type')Unit heater — high-static pressure typevsUnit heater — low-static pressure type
A high-static pressure type circulates air against 0.2 inch water column or greater static pressure and has provisions for attaching an outlet air duct, while a low-static pressure type is intended for installation in the space to be heated without ducts.
IFGC 2015 Section 202 (definition of 'Unit Heater')Low-pressure steam heating boilervsHot water heating / hot water supply boiler
Section 202 limits a steam heating boiler to a steam pressure not exceeding 15 psig, while the 160 psig figure is the water pressure limit stated for hot water heating and hot water supply boilers.
IFGC 2015 Section 202 (definition of 'Boiler, Low-Pressure')Furnace input ratingvsFurnace output rating capacity
Return/outdoor air duct sizing under Section 618.2 is based on the furnace OUTPUT rating capacity (2 square inches per 1,000 Btu/h), not the input rating; using input is a common error.
IFGC 2015 Section 618.2Grille with published, certified (known) free areavsMetal louver with unknown free area
Per Section 304.10, where the free area is known that known value must be used to compute gross area, whereas the 75-percent assumption applies only when the metal louver free area is unknown.
IFGC 2015 Sections 304.10 and 304.6.1Passageway to a room containing appliances (Section 306.2)vsPassageway to appliances in compartments/alcoves/basements within a dwelling unit (exception)
The general rule requires a door and an unobstructed passageway not less than 36 inches wide and 80 inches high, while the reduced 24-inch-wide passageway applies only to the dwelling-unit compartment exception; the 30-inch by 30-inch level working space at the control side is a separate Section 306.1 requirement.
IFGC 2015 Section 306.2Single-wall metal pipe thimble, listed draft-hood appliance, less than 6 ft of pipe in the openvsSame, with not less than 6 ft of metal pipe in the open between draft hood outlet and thimble
Section 503.7.7, Item 1 requires a ventilated thimble not less than 4 inches larger in diameter, but permits not less than 2 inches larger where there is a run of not less than 6 feet of metal pipe in the open; 6-inch and 12-inch figures apply to unlisted draft-hood appliances and residential/low-heat appliances respectively.
IFGC 2015 Section 503.7.7Additional 90-degree elbow (greater than 45 degrees) in a single-appliance ventvsAdditional elbow of 45 degrees or less
Beyond the two 90-degree elbows already included in lateral configurations, each additional elbow greater than 45 degrees requires a 10-percent reduction of the listed maximum capacity, while an additional elbow of 45 degrees or less requires only a 5-percent reduction.
IFGC 2015 Section 504.2.3Gas vent 12 inches or less in size located not less than 8 ft from a vertical wallvsGas vent over 12 inches, or located less than 8 ft from a wall or similar obstruction
The first may terminate above a sloped roof in accordance with Figure 503.6.4, while the second must comply with Item 2 — 2 feet above the roof penetration and 2 feet above any portion of a building within 10 feet horizontally.
IFGC 2015 Section 503.6.4Key Terms
Piping to a special atmosphere generator (scope) IFGC 2015 Section 101.2.4
Section 101.2.4 excludes raw material (feedstock) applications 'except for piping to special atmosphere generators,' so that piping remains within the code's scope, while atomic energy plant fuel gas piping, railroad switch heating LP-gas systems, and temporary LP-gas piping not becoming part of the permanent system are outside the scope.
Board of appeals — fuel gas contractor member IFGC 2015 Section 109.2.1
Where the fuel gas experience seat is filled by a contractor rather than a registered design professional, the contractor must have not less than 10 years' experience, 5 of which shall have been in responsible charge of work (Section 109.2.1).
Mechanical test gauge range IFGC 2015 Section 406.4
Section 406.4 requires mechanical gauges used to measure test pressures to have a range whose highest end of scale is not greater than five times the test pressure (e.g., 15 psig maximum for a 3 psig test).
Manifold appliance shutoff valve IFGC 2015 Section 409.5.3
Section 409.5.3 permits the appliance shutoff valve to be installed at a manifold provided it is located within 50 feet of the appliance served, is readily accessible and permanently identified.
Double block and bleed valve system IFGC 2015 Section 406.1.4
The only condition under Section 406.1.4 in which a valve in a line may serve as a bulkhead between fuel gas in one section and the test medium in an adjacent section during section testing.
Conduit for gas piping in a solid floor IFGC 2015 Sections 404.8 and 404.8.1
Per Sections 404.8/404.8.1, where one end terminates outdoors, the conduit shall extend not less than 4 inches outside the building, be vented above grade to the outdoors, be installed to prevent entrance of water and insects, and extend not less than 2 inches beyond the point where the pipe emerges from the floor.
Reduced clearance protective assembly IFGC 2015 Section 308.2
Section 308.2 permits clearance reduction by a method in Table 308.2 or by a manufactured assembly listed and labeled in accordance with UL 1618.
Stud/joist space used to convey combustion air IFGC 2015 Section 304.11, Item 1 Exception
The exception to Section 304.11, Item 1 permits unobstructed stud and joist spaces within dwelling units to convey combustion air provided not more than one required fireblock is removed; all other Section 304.11 duct provisions still apply.
Sauna heater warning notice IFGC 2015 Section 615.4
Section 615.4 allows a posted warning notice where the combustion air inlet and draft hood are in a dressing room adjacent to the sauna room; the notice must be easily readable, contrast with its background, and use letters not less than 1/4 inch high.
Alternative area method (chimney serving two draft-hood appliances) IFGC 2015 Section 503.5.5
Per Section 503.5.5, Item 3, the effective area of the chimney flue shall be not less than the area of the larger draft hood outlet plus 50 percent of the area of the smaller draft hood outlet, and not greater than seven times the smallest draft hood outlet area.
Combination indoor and outdoor combustion air (Section 304.7.3) IFGC 2015 Section 304.7.3
The ratio of interior spaces equals available volume of communicating spaces divided by required volume, and the outdoor opening size reduction factor is one minus that ratio, applied to the opening size calculated per Section 304.6; the opening's minimum dimension must still be not less than 3 inches.
One-permanent-opening method (Section 304.6.2) IFGC 2015 Section 304.6.2
Where outdoor combustion air is supplied through a single permanent opening commencing within 12 inches of the top of the enclosure, the appliance shall have clearances of not less than 1 inch from the sides and back and 6 inches from the front.
Standard method for indoor combustion air (Section 304.5.1) IFGC 2015 Sections 304.5 and 304.5.1
Where the infiltration rate is unknown, the space must have a minimum volume of 50 cubic feet per 1,000 Btu/h, based on the total input of all appliances in the space (Section 304.5).
Mechanical combustion air supply (Section 304.9) IFGC 2015 Section 304.9
Where all combustion air is provided by a mechanical air supply system, outdoor air shall be supplied at not less than 0.35 cfm per 1,000 Btu/h of total input, and Section 304.9.2 requires each appliance to be interlocked with the air supply system.
Indoor piping design operating pressure exceeding 5 psig IFGC 2015 Section 402.6
Section 402.6, Item 6 permits an indoor piping system to exceed 5 psig where it is an LP-gas piping system with a design operating pressure greater than 20 psi that complies with NFPA 58.
Line pressure regulator IFGC 2015 Section 410.1
Section 410.1 requires a line pressure regulator where the appliance is designed to operate at a lower pressure than the supply pressure, and such regulators must be listed as complying with ANSI Z21.80 (ANSI Z21.15 is manual gas valves, Z21.24 listed appliance connectors, Z21.69 connectors for movable/commercial cooking appliances).
Table 402.4(2) conditions IFGC Table 402.4(2), Schedule 40 Metallic Pipe (natural gas, inlet < 2 psi, 0.5 in. w.c. drop, SG 0.60)
Schedule 40 metallic pipe capacities for natural gas at inlet pressure less than 2 psi, 0.5 inch w.c. pressure drop, and 0.60 specific gravity.
Formulas to Know
Convert appliance input to gas demand and table capacity to Btuh (natural gas, 1,000 Btu per cubic foot)
cfh = Btu/h ÷ 1,000; Btu/h capacity = table cfh × 1,000 (e.g., 30,000 ÷ 1,000 = 30 cfh; 247 cfh × 1,000 = 247,000 Btuh)Spare (or short) capacity of an installed pipe
Spare cfh = table capacity at that length and size − appliance demand (example: 247 cfh − 35 cfh = 212 cfh spare; 44 − 40 = 4 cfh; 117 − 40 = 77 cfh)Longest length method — table row selection
Measure meter to the most remote outlet; if no exact row exists use the next longer row, and use that one row to size every section (example: 75 ft → 80-ft row; 70 ft → 70-ft row)Branch length method — length for a branch
Branch length = main length from meter to its tee + branch length, then use the next longer table row (example: 30 + 15 = 45 ft → 50-ft row; 15 + 5 = 20 ft → 20-ft row); main sections on the longest run use the longest-run row, each sized for the load of the outlets it serves (section A at the meter carries the whole load, e.g. 115 cfh, while downstream section B carries only outlets 2–3, e.g. 75 cfh)Section load and minimum pipe size
Section load = sum of the inputs of all outlets it serves ÷ 1,000; select the smallest pipe size in the governing length row whose capacity meets or exceeds that load (example: Section A, 340 cfh, 80-ft row → 1-1/4 inch at 452 cfh)Outdoor combustion air — two permanent openings, direct or vertical duct (Section 304.6.1)
Free area per opening = total input Btu/h ÷ 4,000 (example: 120,000 ÷ 4,000 = 30 sq in each; 200,000 ÷ 4,000 = 50 sq in each); horizontal ducts use 1 sq in per 2,000 Btu/hGross grille area where free area is known (Section 304.10)
Gross area = required net free area ÷ known free-area fraction (example: 50 sq in ÷ 0.40 = 125 sq in)Combination indoor/outdoor combustion air opening (Section 304.7.3)
Reduction factor = 1 − (available volume of communicating spaces ÷ required volume); minimum outdoor opening = full Section 304.6 opening size × reduction factor (example: 1 − 0.70 = 0.30; 50 sq in × 0.30 = 15 sq in)Indoor combustion air volume, standard method (Section 304.5.1)
Required volume = total appliance input Btu/h ÷ 1,000 × 50 cubic feet (example: 120,000 ÷ 1,000 × 50 = 6,000 cu ft)Mechanical combustion air supply rate (Section 304.9)
Minimum supply = 0.35 cfm per 1,000 Btu/h of total input (example: 400 × 0.35 = 140 cfm)Return/outdoor air duct area for a forced-air furnace (Section 618.2)
Minimum unobstructed area = furnace OUTPUT rating Btu/h ÷ 1,000 × 2 square inches (example: 120,000 ÷ 1,000 × 2 = 240 sq in), unless manufacturer's instructions state larger