CSLB C-36 Plumbing ContractorRough-in PlumbingHard
A plumbing contractor is roughing in a new gas piping system for a commercial building. The system uses Schedule 40 black steel pipe. What is the maximum allowable length of an unthreaded (plain end) steel pipe nipple that can be used in the system without requiring special engineering or approval?
- A3 inches
- B6 inches
- C8 inches
- D12 inches
Show answer & explanationAnswer & explanation
Correct answer: B. 6 inches
According to the California Plumbing Code (CPC), unthreaded gas pipe nipples should generally not exceed 6 inches in length. Longer nipples can be more prone to damage or bending, especially in an unthreaded configuration, unless specifically engineered and approved.
Why the other options are wrong
- A. 3 inches is well within limits but not the maximum.
- C. 8 inches exceeds the standard code limit for unthreaded nipples.
- D. 12 inches is too long for an unthreaded nipple in this context without specific engineering.
Gas Pipe Nipple Length
A short piece of pipe, often threaded on both ends, used to connect other fittings or pipes in a gas system. Unthreaded nipples have specific length limitations.
- Used for short connections.
- Threaded nipples are common; unthreaded are less so in gas.
- Length limits prevent excessive leverage or stress on connections.
Memory trick: Nipple for gas, a short pass, 6 inches is the max, no more, alas.