Things You Should Know About the Pipe Union
Pipe unions are what you use to connect two pipes together securely and on a semi-permanent basis. Like pipes, they are threaded so a firm connection can be created. Although they have many similarities to couplings, they can be easily taken apart and allow all sorts of pipes to be safely connected together. This is usually seen in commercial and house plumbing systems.
How are the coupling and the union similar? They allow two pipes to be connected together using the very same threading system that pipes have. What makes them differ, however, is the way they join pipes. The coupled pipes need to be screwed together directly, with one pipe placed inside the other. If they have to be taken apart, each pipe connected to those two pipes has to be removed. If a property has a full pipe system, the whole system of pipes has to be disassembled to take out a single pipe.
By having a pipe union, the ends of two pipes do not screw into each other. Instead, each of them is screwed into a third, middle piece. If a pipe has to be taken out of a system, the union stays on the end of a pipe. If the two ends of a single piece of pipe have a union attached to each end, you can take out that particular piece without removing the others in the system.
Aside from connecting two pipes together, a pipe union also serves as a protection system. Often made out of plastic, they keep two different pipes from touching. This is important, as galvanic corrosion happens when two metals touch a single conductive material. Conductive liquids, like water, will cause the movement of electrons from a material to the next one. This causes the dissolution of one pipe and the accretion of materials (from the other pipe) by the other pipe.
In other words, the union serves to bring two pipes together but prevent them from getting in direct contact with each other. The latter is possible due to the plastic barrier in its middle. Keep in mind that it does not completely stop galvanic corrosion from happening. It does, however, dramatically slow it down.
The pipe union is so common that you may not notice them among the pipes in your house’s plumbing system. They are often used due to being so easy to fix and maintain. The downside of having a pipe union, however, is the likelihood of a leak due to having threaded parts. For this reason, plumbers will tell you that they are not best for connecting pipes that are intended for delivering high-pressure or dangerous liquids.