Question 1

According to the IFGC, what is the minimum test pressure required for a gas piping system withstand test?

Accepted Answer

IFGC 406.4.1 requires the test pressure to be 1.5 times the proposed maximum working pressure, but generally not less than 3 psig.

Question 2

The test duration for a gas piping system with a test pressure of less than 10 psig shall be not less than:

Accepted Answer

IFGC 406.4.2 states the test duration shall be not less than 10 minutes.

Question 3

Gas shutoff valves shall be located within ___ feet of the appliance they serve.

Accepted Answer

IFGC 409.5.1 requires the shutoff valve to be located in the same room as the appliance and within 6 feet of the appliance.

Question 4

Plastic pipe (PE, PVC) used for gas piping shall be installed:

Accepted Answer

IFGC 403.6 prohibits plastic pipe for use within buildings. It is allowed outdoors underground only.

Question 5

What is the minimum burial depth for underground gas piping?

Accepted Answer

IFGC 404.12 requires gas piping underground to be installed not less than 12 inches below grade (except for individual lines to outdoor lights/grills which can be 8 inches if protected).

Question 6

A sediment trap (drip leg) is required:

Accepted Answer

IFGC 408.4 requires sediment traps (often called dirt legs) to be installed downstream of the appliance shutoff valve to catch debris before it enters the gas valve.

Question 7

The unthreaded portion of gas piping outlets shall extend not less than ___ inches through finished ceilings or walls.

Accepted Answer

IFGC 404.16 requires the unthreaded portion of piping outlets to extend at least 1 inch beyond finished ceilings or walls.

Question 8

Standard Method: The minimum required volume of indoor combustion air is ___ cubic feet per 1,000 BTU/h of the appliance input rating.

Accepted Answer

IFGC 304.5.1 states the minimum volume shall be 50 cubic feet per 1,000 BTU/h.

Question 9

Unvented room heaters shall not be installed in:

Accepted Answer

IFGC 303.3 prohibits unvented fuel-burning heaters in bedrooms or bathrooms (unless it's a specific wall-mounted heater equipped with an oxygen depletion sensor and meets BTU limits).

Question 10

Gas piping installed in a concealed location shall not contain:

Accepted Answer

IFGC 404.5 prohibits unions, tubing fittings, right/left couplings, bushings, compression couplings, and running threads in concealed locations (walls/floors) to prevent leaks.

Question 11

Appliance fuel connectors shall have a maximum overall length of:

Accepted Answer

IFGC 411.1.3.1 limits the length of flexible appliance connectors to 6 feet.

Question 12

CSST (Corrugated Stainless Steel Tubing) gas piping systems must be:

Accepted Answer

IFGC 310.1.1 requires CSST to be bonded to the electrical service grounding electrode system to prevent arc damage from lightning strikes.

Question 13

Underground gas piping carrying Propane (LPG) allows:

Accepted Answer

Polyethylene (PE) is the standard plastic allowed for underground gas (Natural or LP). Schedule 40 PVC is generally prohibited for gas due to brittleness.

Question 14

Supports for 3/4-inch rigid steel gas pipe shall be spaced not more than ___ feet apart.

Accepted Answer

IFGC Table 415.1 requires 3/4-inch or 1-inch steel pipe to be supported every 8 feet. (1/2-inch is 6 feet).

Question 15

A gas vent connector shall slope upward toward the vent or chimney at least:

Accepted Answer

IFGC 503.10.7 requires a minimum upward slope of 1/4 inch per foot to ensure draft.

Question 16

Where gas piping penetrates a foundation wall underground, it must be:

Accepted Answer

IFGC 404.6 requires piping passing through a foundation wall to be encased in a protective sleeve and sealed to prevent gas entry into the building.

Question 17

Liquefied Petroleum Gas (LPG) is heavier than air. Natural Gas is:

Accepted Answer

Natural gas (Methane) is lighter than air (Specific Gravity ~0.60), causing it to rise and dissipate. Propane is heavier (SG ~1.50) and pools in low spots.

Question 18

Thread joint compounds (pipe dope) used on gas piping must be:

Accepted Answer

IFGC 403.9.3 requires pipe joint compound to be resistant to the chemical action of LP gas.

Question 19

When using the 'Longest Length Method' to size gas piping, you measure from the point of delivery (meter) to:

Accepted Answer

The Longest Length Method requires measuring from the delivery point to the most remote outlet, then using that single length to size the entire system.

Question 20

Underground gas piping marked with a yellow tracer wire is likely:

Accepted Answer

Plastic pipe is non-conductive, so IFGC 404.17.3 requires an electrically continuous yellow tracer wire (minimum AWG 18) to be installed with it for locating purposes.

Question 21

Category I gas appliances rely on:

Accepted Answer

Category I appliances operate with a non-positive vent static pressure and a vent gas temperature that avoids excessive condensation (standard atmospheric draft).

Question 22

Which valve is prohibited for use as a gas shutoff valve?

Accepted Answer

Gas valves must be approved for gas service (often marked WOG or Gas). Standard water gate valves are not approved for gas isolation.

Question 23

Gas piping shall not be used as a:

Accepted Answer

IFGC 310.1 prohibits using gas piping as a grounding electrode (ground rod). It must be bonded *to* the ground, but not used *as* the ground path for the electrical system.

Question 24

The approximate BTU content of 1 cubic foot of Natural Gas is:

Accepted Answer

Standard natural gas contains approximately 1,000 to 1,050 BTUs per cubic foot. (Propane is ~2,500).

Question 25

When purging a gas line of air, if the piping is larger than ___ inches, the purge gas must be discharged outdoors.

Accepted Answer

IFGC 406.7.2 requires that purging of gas piping larger than 2 inches nominal diameter be performed by discharging the gas to the outdoors, away from any source of ignition. For piping 2 inches or smaller, indoor purging with specific precautions may be permitted under certain conditions. The 2-inch threshold is the key dividing line for mandatory outdoor purge discharge requirements.

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