Master Plumber Gas Piping Systems Questions and Answers

Question 1

A master plumber is installing a natural gas piping system with a proposed maximum working pressure of 0.5 psi. According to the IFGC, what is the minimum required test pressure and duration for this new piping system before any appliance is connected?

Accepted Answer

3.0 psi for 10 minutes

Answer

The International Fuel Gas Code (IFGC) section 406.4.1 states that the test pressure to be used shall be no less than 1-1/2 times the proposed maximum working pressure, but not less than 3 psig (20 kPa gauge), irrespective of the design pressure. Since 1.5 times 0.5 psi is 0.75 psi, the minimum test pressure defaults to 3 psig. Section 406.4.2 specifies the test duration shall be not less than 10 minutes.

Question 2

When installing a sediment trap for a gas furnace, which of the following configurations is correct according to most fuel gas codes?

Accepted Answer

A tee fitting with the gas flow entering the top of the tee and exiting the side outlet, with a capped nipple on the bottom.

Answer

A sediment trap must be configured to change the direction of gas flow, forcing debris to fall out of the gas stream. The correct installation involves a tee fitting where the gas enters the top, makes a 90-degree turn to exit the side outlet towards the appliance, and a capped nipple (minimum 3 inches long) is installed in the bottom opening to collect sediment.

Question 3

A plumber is running Corrugated Stainless Steel Tubing (CSST) through a new wood-framed wall. The tubing is located 1 inch from the face of a stud. Which of the following is required by the IFGC?

Accepted Answer

A steel striker plate must be installed to protect the tubing.

Answer

When CSST or other gas piping is installed through wood members in a concealed location and is less than 1-1/2 inches from the nearest edge of the member, it must be protected by a steel shield plate not less than 0.0575 inches (14 gauge) thick. This plate protects the tubing from puncture by nails or screws.

Question 4

According to the IFGC, which of the following locations is explicitly prohibited for the installation of gas piping?

Accepted Answer

Through a clothes chute or elevator shaft.

Answer

The IFGC Section 404.3 expressly prohibits the installation of gas piping in or through a circulating air duct, clothes chute, chimney or gas vent, dumbwaiter, or elevator shaft. These are areas where a gas leak could quickly spread throughout the building or be difficult to detect and repair.

Question 5

A master plumber is sizing a natural gas piping system using the longest length method. The most remote appliance is a furnace located 75 feet from the meter. The total connected load for the entire system is 250,000 BTU/hr. Using a standard sizing table for 0.5 psi gas pressure with a 0.5-inch water column pressure drop, which sizing column should be used to size ALL pipe sections?

Accepted Answer

The column for the next length longer than 75 feet, such as 80 or 90 feet.

Answer

When using the 'longest length method' for gas pipe sizing, the first step is to determine the distance from the point of delivery (meter) to the most remote appliance. This single length is then used to size every section of pipe in the entire system. If the exact length is not listed in the sizing table, the next longer length shown must be used.

Master Plumber Exam Practice Test

Master Plumber Exam Practice Test

Master Plumber Gas Piping Systems Questions and Answers