A union for joining copper pipe is typically made of brass, and it has slip connections so you can solder it onto the pipes. You join the union by tightening the central nut. It pulls the two halves of the fitting together and seats them into a washer, which makes the seal.

What does a brass union do?

Manufactured from high-quality lead-free brass and complies with NSF 61, ASTM B62 and ANSI standards. Threaded union is used to connect two threaded pipes together and allows for easy disconnection of these pipes for service, repair, maintenance or other purposes.

What is the correct way to install a pipe union?

Thread the male half of the union nut onto the left-side pipe, and tighten it securely. Slip the ring nut portion of the union onto the right-side pipe with the threads facing outward. Thread on the other half of the union nut, and tighten it securely.