What is a common use of unions in piping systems?

Unions are fittings used in piping systems that allow for easy connection and disconnection of pipes. They are particularly valuable in situations where maintenance, repair, or replacement of piping components is necessary. By using a union, a technician can quickly separate a section of the piping without needing to cut and rethread the pipe, which saves time and reduces the need for additional materials or tools. This capability is essential in many industrial and commercial applications where minimizing downtime is crucial.

The other options focus on functions that unions do not perform. While regulating pressure is typically managed with valves, preventing backflow involves check valves, and thermal insulation requires different materials designed to minimize heat transfer. Unions specifically excel in offering a convenient method for managing connections in pipes.