Which statement correctly distinguishes a pipe nipple from a pipe coupling?

Which statement correctly distinguishes a pipe nipple from a pipe coupling?

• A. A nipple is a short threaded piece with male threads on both ends; a coupling joins two pipes end-to-end
• B. A nipple has female threads on both ends
• C. A nipple is used to connect a pipe to a valve
• D. A coupling is a short threaded piece with male threads on both ends

Answer: (A)

Understanding how these fittings differ comes down to threading on the ends and how they’re used in a line. A pipe nipple is a short piece of pipe with male threads on both ends; it is used to extend or connect two fittings that have matching female threads. A pipe coupling is a short piece that joins two pipe ends end-to-end and typically has female threads on both ends to receive the male threads of the pipes or fittings. Therefore, the statement that identifies a nipple as a short threaded piece with male threads on both ends and that a coupling serves to connect two pipes end-to-end correctly captures the distinction. The other options misstate the threading of a nipple or the function of a coupling (for example, describing a nipple as having female threads, or suggesting a nipple is used specifically to connect to a valve, or describing a coupling as male-threaded).

Understanding how these fittings differ comes down to threading on the ends and how they’re used in a line. A pipe nipple is a short piece of pipe with male threads on both ends; it is used to extend or connect two fittings that have matching female threads. A pipe coupling is a short piece that joins two pipe ends end-to-end and typically has female threads on both ends to receive the male threads of the pipes or fittings. Therefore, the statement that identifies a nipple as a short threaded piece with male threads on both ends and that a coupling serves to connect two pipes end-to-end correctly captures the distinction. The other options misstate the threading of a nipple or the function of a coupling (for example, describing a nipple as having female threads, or suggesting a nipple is used specifically to connect to a valve, or describing a coupling as male-threaded).