Master Plumber Practice Exam 2026 – Complete Prep Guide

In the context of cast iron piping, the most common and acceptable joining methods are bell and spigot, and threaded connections. The bell and spigot method is typically used for gravity flow systems and allows for easy assembly and disassembly, which is advantageous for maintenance. Threaded joints provide a robust and reliable connection that is commonly utilized in various plumbing applications involving cast iron.

Welded joints are not suitable for cast iron because welding can change the structural integrity and mechanical properties of the material, potentially leading to weakening or even cracking. On the other hand, soldered joints are inappropriate for cast iron as they are usually used with softer metals, and the process can damage the cast iron.

Therefore, the threading method is specifically recognized for its compatibility with cast iron fixtures and fittings, while welded and soldered joints are excluded due to the fundamental characteristics of cast iron and the risks associated with those joining methods.