A plumber is installing a 100 mm cast iron sanitary drainage line in a commercial building. The plans specify a hubless coupling for a connection between two sections of pipe. What is the primary advantage of using a hubless coupling in this application compared to a hub and spigot joint?

Question: A plumber is installing a 100 mm cast iron sanitary drainage line in a commercial building. The plans specify a hubless coupling for a connection between two sections of pipe. What is the primary advantage of using a hubless coupling in this application compared to a hub and spigot joint?

Answer options:

• It provides a more rigid, permanent connection that is less prone to movement. ✅ It eliminates the need for specialized tools like a caulking iron or lead pot.
• It can be easily disassembled for future modifications or repairs without cutting the pipe.
• It offers superior resistance to chemical attack and high-temperature waste streams.

Correct answer: It eliminates the need for specialized tools like a caulking iron or lead pot.

Explanation: Hubless couplings eliminate the need for molten lead and oakum, or mechanical compression, simplifying installation and removing the requirement for specialized caulking tools. While rigid and permanent, it's not the primary advantage over hub and spigot. Disassembly can be done, but it's not its main benefit over other methods. Resistance to chemical attack is a property of the pipe material itself, not primarily the coupling.