Unions

What Is a Union Used For in Plumbing?

A union is a plumbing fitting (black, galvanized, copper, pvc, brass, stainless steel and more...) that allows two pipes to be connected and later disconnected easily without cutting the pipe.

Its main function is to:

• Create a removable connection
• Allow equipment to be serviced or replaced
• Keep piping intact during maintenance

How a Union Works

A union is made of three pieces:

• One half with threads or connection end
• Other half with threads or connection end
• A center nut that pulls the two halves together
• When the nut is tightened, the two ends seal together.
• When loosened, the pipe can be separated.

What Unions Are Used For

Unions are installed wherever equipment may need to be removed, such as:

• Water heaters
• Boilers
• Pumps
• Filters and softeners
• Gas appliances
• Valves and regulators
• They prevent having to cut and re-pipe later.

Union vs Coupling

• Fitting Can Be Disconnected Later with a union and not with a coupling?
• A coupling is permanent.
• A union is serviceable.

Common Materials

• Brass
• Black malleable iron
• Copper
• Stainless steel
• PVC / CPVC
• Available in threaded, sweat, press, and solvent-weld styles.

Simple Example

You install a water heater with a union on the hot and cold lines. When the heater eventually fails, you simply loosen the unions and remove it—no cutting required.

In Plain English

A union lets you take piping apart and put it back together without destroying the system.