Journeyman Plumber ExamGas PipingEasy
A plumber is installing an outdoor gas grill. The gas supply line will be run underground from the main house supply. What type of piping material is typically approved for direct burial for natural gas residential applications?
- ABlack iron pipe
- BGalvanized steel pipe
- CCopper tubing
- DPolyethylene (PE) pipe
Show answer & explanationAnswer & explanation
Correct answer: D. Polyethylene (PE) pipe
Polyethylene (PE) pipe is commonly approved for direct burial natural gas applications due to its corrosion resistance and flexibility. Galvanized steel and black iron pipe are susceptible to corrosion underground, and copper is generally not permitted for natural gas underground unless specifically listed and protected, due to potential for corrosion or reaction with gas components.
Why the other options are wrong
- A. Black iron pipe is also highly susceptible to corrosion when directly buried and is not typically approved without extensive protection.
- B. Galvanized steel pipe is not generally approved for direct burial gas lines due to its susceptibility to corrosion in soil.
- C. Copper tubing is generally not permitted for natural gas underground due to potential for corrosion or reaction with certain gas compounds, unless specifically identified for such use and properly protected.
Direct Burial Gas Piping
Gas piping specifically approved and designed for installation directly into the ground without additional protective measures (beyond typical backfill).
- Must be corrosion-resistant.
- Polyethylene (PE) is a common material.
- Requires proper identification and depth.
Memory trick: PE underground, safe and sound, no rust around!