In many cases, the best choice for joining two lengths of pipe together is using solder to actually weld them together (this is called a “sweat joint”). But there are other times when soldering isn’t practical or even possible, especially in inaccessible spots or systems where using a torch and solder would create a fire hazard. In these cases, a compression fitting is the better choice. Here’s what you need to understand about compression valves and fittings:

How Compression Fittings Work

As their name suggests, compression fittings work because something is compressed. In this case, that something is an internal ring called a ferrule or olive. When an outer nut is screwed onto the compression fitting, the ferrule is tightened around the length of pipe, creating a leak-resistant seal (particularly effective in containing water, but also used in numerous other types of systems. Even if you remove the compression nut, you’ll see that the ferrule has been tightened around the pipe in question. Sometimes the seal of a compression fitting is amplified using PTFE tape, a special plumbing material that makes joints even more waterproof.

Choosing the Right Compression Fittings

So how can you choose the right compression fitting for the job? The first thing to look at is the material. Brass compression fittings are one popular choice (as are brass pipe fittings in general) because brass fittings are very strong and yet moldable enough for compression applications. Just be sure if you’re working with drinking water systems that you’re using lead free compression fittings; some brass compression fittings have small amounts of lead in them for added strength, but there’s new legislation limiting their use depending on the situation. After that, it’s as simple as choosing the right size based on the pipes that you’re using. Compression fittings come in a wide variety of sizes, and therefore can be used on everything from medical devices to large-scale plumbing systems.

Do you have anything to add regarding compression fittings? Join the discussion in the comments.