Plumbing Problems With Copper Compression Fittings

Copper Pipes

• Two types of copper pipe are commonly used in plumbing. Soft copper tubing, which can be bent and shaped relatively easily, is often used for water-supply lines under slab foundations. Some gas lines are also made of soft copper pipe. Hard copper pipe is often used to carry hot and cold water throughout a home. Compared with other metal pipe, copper pipe is easy to cut. Generally, plumbers solder hard copper pipe to hard copper pipe and soft copper pipe to soft copper pipe. They use compression fittings to join hard copper pipe to soft copper pipe and to join copper pipe to another metal, such as brass or galvanized steel.

Compression Fittings

• A compression fitting, which is often made of brass, is designed to hold two pipes together snugly. The fitting has three parts: a nut, a ring and a seat. The plumber slides the nut and the ring onto the pipe. Then he slides the pipe into the fitting and tightens the nut. The ring is pressed into the seat as the plumber tightens the nut, making a tight connection. Too much force, however, can crimp the delicate copper pipe, blocking the flow of water. And if there's not enough pressure, the seal won't be secure, and leakage will result.

Electrolysis

• Using a compression fitting to connect copper to steel can be problematic. When the brass in the fitting and the copper meet the steel, a process called electrolysis can ensue. Water flowing through the pipes carries electrons from the steel pipe to the copper, leading to corrosion. Over time, this creates holes where the pipes meet. The severity of the problem depends on the temperature and the hardness of the water. To prevent electrolysis, use a dielectric union fitting. This has a plastic spacer inside the fitting to prevent metal-on-metal contact.

Leaks

• Leaking can be a problem with compression fittings. A fitting may be too loose because it was not screwed on tightly enough. Vibration can also loosen the fitting. Tightening the nut enough to create a secure seal is usually the fix for this problem. The fitting should not be tightened too much, however, because that can also cause a leak. A leaky fitting that is too tight requires replacement of the pipe and connection.