Journeyman Plumber ExamGas PipingEasy
When installing a new segment of black iron pipe for a natural gas system, what is the generally accepted and required method for making threaded connections to ensure a leak-free seal?
- AUsing only Teflon tape applied in the direction of tightening.
- BApplying pipe joint compound to the male threads only, ensuring a thin, even coat.
- CUsing only pipe joint compound applied to both male and female threads.
- DApplying pipe joint compound (pipe dope) to the male threads only, along with Teflon tape.
Show answer & explanationAnswer & explanation
Correct answer: B. Applying pipe joint compound to the male threads only, ensuring a thin, even coat.
For threaded gas pipe connections, pipe joint compound (pipe dope) specifically approved for gas is applied to the male threads only. Applying it to female threads or excessively can lead to material entering the gas stream. Teflon tape alone is often not sufficient or approved for gas lines in many jurisdictions.
Why the other options are wrong
- A. Teflon tape alone is often not approved or sufficient for gas pipe seals; it can also shred and enter the gas stream if not applied correctly.
- C. Applying pipe dope to both threads is incorrect for the same reason as applying to female threads, and tape is often recommended alongside dope.
- D. Applying pipe dope to female threads is incorrect as it can push material into the pipe, potentially clogging regulators or orifices.
Threaded Gas Pipe Sealing
The proper method of applying sealing compounds to threaded gas pipe connections to prevent leaks.
- Use approved pipe joint compound.
- Apply only to male threads.
- Ensure a thin, even coat.
Memory trick: Dope on Male, Seal it tight, Gas stays inside, all is right!