When should a plumber use a union fitting?

A union fitting is specifically designed to facilitate easy disassembly of pipe connections. This makes it particularly advantageous in situations where maintenance or repairs may be necessary. When a plumber anticipates needing to access or replace a section of piping, using a union allows for quicker and more efficient disconnection without needing to cut the pipe or use additional tools that would otherwise complicate the process.

While it’s true that other fittings serve different purposes, a union fitting's broad applicability in maintenance settings makes it the ideal choice when disassembly is a consideration. This contrasts with fixed connections, which typically use other types of fittings that secure pipes in static configurations, or with connecting different pipe sizes, which would employ various reducing fittings tailored to match diameters. Decorative plumbing applications may utilize unions in specific instances, but that is not the primary function or best use case for these fittings.