Journeyman Plumber ExamGas PipingEasy
A plumber is performing a final inspection of a newly installed gas piping system in a commercial building. Which of the following is NOT an acceptable material for gas piping within a building according to most plumbing codes?
- ACopper tubing (Type L or K)
- BPVC (Polyvinyl Chloride) pipe
- CBlack steel pipe
- DCorrugated Stainless Steel Tubing (CSST)
Show answer & explanationAnswer & explanation
Correct answer: B. PVC (Polyvinyl Chloride) pipe
PVC (Polyvinyl Chloride) pipe is not approved for gas distribution within buildings due to its susceptibility to degradation from hydrocarbons in natural gas, its lack of fire resistance, and its inability to withstand the pressures and temperatures typically encountered in gas systems. It is sometimes used for underground gas service lines outside of buildings, but never inside.
Why the other options are wrong
- A. Copper tubing (Type L or K) is approved for gas piping in many jurisdictions, provided it meets specific wall thickness requirements and is properly installed.
- C. Black steel pipe is a widely accepted and common material for gas piping inside buildings.
- D. CSST is a commonly approved and popular material for gas piping, especially for its flexibility and ease of installation.
Approved Gas Piping Materials
Gas piping materials must be specifically approved by code for their intended application, ensuring compatibility with natural gas, durability, and safety under operating conditions.
- Material selection is critical for safety and longevity.
- Common materials include black steel, CSST, and approved copper.
- Plastics like PVC are generally prohibited indoors.
Memory trick: Gas pipes must be 'Strong' and 'Safe' – NOT 'Plastic' or 'Weak'.