G2 Gas Fitter Practice Exam

What is the minimum pipe diameter for underground installation?

1. 1 NPS

2. 3/4 NPS

3. 1/2 NPS

4. 1 1/4 NPS

The correct answer is: 1/2 NPS

For underground installation of gas pipes, the minimum pipe diameter is typically specified to ensure adequate gas flow while minimizing the risk of pressure drops and allowing sufficiency for proper operation. In many jurisdictions and standards, a nominal pipe size of 1/2 inch is often considered the minimum acceptable diameter for underground gas piping. Using a 1/2 NPS (Nominal Pipe Size) allows for the safe transport of gas in residential settings, addressing common installation scenarios. This size is particularly suitable for connecting appliances such as water heaters, furnaces, and stoves, which generally do not require larger diameter pipes. Furthermore, a smaller diameter pipe like 1/2 NPS can effectively fit in typical residential trenching without excessive excavation, thus adhering to construction and installation best practices. Pipes with larger diameters, while acceptable for certain applications, are not required for most standard installations, which is why they are considered above the minimum requirement. Consequently, the selection of 1/2 NPS aligns with the minimum standard guidelines that promote safety and efficiency in gas service installations.