Journeyman Plumbers Gas Piping Systems Questions and Answers — Questions and Answers
Question 1: A plumber is installing a new natural gas piping system that will operate at a standard pressure of 7 inches water column (approx. 0.25 psi). According to the International Fuel Gas Code (IFGC), what is the minimum required air pressure test for this new installation?
- 3 psig for a minimum of 10 minutes (Correct answer)
- 10 psig for a minimum of 5 minutes
- 0.5 psig for a minimum of 30 minutes
- 1.5 times the operating pressure for 15 minutes
Correct answer: 3 psig for a minimum of 10 minutes
According to IFGC section 406.4.1, for a gas system with a proposed maximum working pressure less than or equal to 0.5 psi, the test pressure must be no less than 1.5 times the working pressure, but not less than 3 psig. The test duration must be a minimum of 10 minutes.
Question 2: A plumber is installing a gas line to a new furnace. To protect the appliance's controls from particulate matter, a sediment trap is required. Based on model fuel gas codes, which of the following describes the correct installation of a sediment trap?
- Upstream of the appliance shutoff valve, as close to the main as possible.
- On the vertical pipe dropping down to the appliance, with gas flow passing straight through the tee.
- Downstream of the appliance shutoff valve and before the flexible appliance connector. (Correct answer)
- Only on appliances located in basements or crawlspaces.
Correct answer: Downstream of the appliance shutoff valve and before the flexible appliance connector.
Fuel gas codes require a sediment trap to be installed downstream of the appliance's shutoff valve, as close to the inlet of the appliance as practical, and before any flexible connector. It must be configured with a tee fitting to force a 90-degree change in gas flow, allowing sediment to fall into the capped nipple.
Question 3: When installing Corrugated Stainless Steel Tubing (CSST) for a natural gas system, what specific safety measure is mandated by the manufacturer and fuel gas codes to protect against electrical hazards?
- Wrapping the entire length of tubing in an approved insulating tape.
- Installing a dielectric union at the connection to every appliance.
- Bonding the CSST system directly to the building's electrical service grounding electrode system. (Correct answer)
- Ensuring the CSST is installed with at least 6 inches of separation from all electrical wiring.
Correct answer: Bonding the CSST system directly to the building's electrical service grounding electrode system.
To mitigate the risk of damage from electrical arcing (such as from a nearby lightning strike), CSST systems must be bonded to the building's electrical service grounding electrode system. This is typically accomplished with a minimum 6 AWG copper wire and a proper bonding clamp attached to a rigid pipe component or CSST fitting.
Question 4: Which of the following locations is strictly prohibited for the installation of gas piping according to the International Fuel Gas Code?
- In an accessible, vented attic space.
- Beneath a concrete slab, when sleeved in an approved conduit.
- In a concealed wall space of a residential home.
- Through a circulating air duct or chimney. (Correct answer)
Correct answer: Through a circulating air duct or chimney.
The IFGC explicitly prohibits the installation of gas piping in or through circulating air ducts, clothes chutes, chimneys, gas vents, dumbwaiters, or elevator shafts. A gas leak in these locations could quickly and dangerously spread throughout the building.
Question 5: A plumber is running an underground polyethylene (PE) gas line to an outdoor barbecue grill. According to the IFGC, how must the PE pipe be transitioned for the above-ground connection to the appliance?
- PE pipe can be run directly to the appliance if it is painted yellow for visibility.
- The PE pipe must transition to an approved metallic pipe using a manufactured anodeless riser before it emerges from the ground. (Correct answer)
- A section of copper tubing must be used for the last 18 inches below grade before transitioning above ground.
- The PE pipe can extend up to 6 inches above grade if it is sleeved in schedule 40 PVC.
Correct answer: The PE pipe must transition to an approved metallic pipe using a manufactured anodeless riser before it emerges from the ground.
Polyethylene (PE) plastic piping is not approved for above-ground use due to its susceptibility to UV degradation and physical damage. It must be terminated below grade and connected to an approved above-ground piping material, typically through a pre-manufactured anodeless riser or other approved transition fitting.
Question 6: When sizing a low-pressure (less than 2 psi) natural gas piping system using the longest-run method, what are the three primary factors used in the sizing tables found in the IFGC?
- Pipe material, outdoor temperature, and number of fittings.
- The longest developed length of pipe, the total connected BTU/hr load, and the pipe size. (Correct answer)
- The building's elevation, the specific gravity of the gas, and the supply pressure.
- The number of appliances, the pipe wall thickness, and the meter pressure.
Correct answer: The longest developed length of pipe, the total connected BTU/hr load, and the pipe size.
Standard gas pipe sizing tables, such as those in Chapter 4 of the IFGC, are organized based on three key pieces of information: the longest developed length of piping from the point of delivery (meter) to the furthest appliance, the total connected appliance load in BTU/hr, and the nominal pipe size.
Journeyman Plumbers Gas Piping Systems Questions and Answers
A plumber is installing a new natural gas piping system that will operate at a standard pressure of 7 inches water column (approx. 0.25 psi).
According to the International Fuel Gas Code (IFGC), what is the minimum required air pressure test for this new installation?