How to Get a Coupling Over a Lip on a Copper Pipe

Couplings

• Couplings constitute a type of fitting, and possibly the simplest of all fittings. A standard coupling consists of nothing more than a small joint, with equally sized openings on either end, designed to fit over the lip of two pipes and joint them. A few types of other couplings exist. A slip coupling, for instance, consists of a length of pipe installed as a fitting. A reduction coupling, meanwhile, looks just like a standard coupling, but with one opening larger than the other. Reduction couplings exist to joint pipes of different sizes.

Sizing

• In order to properly fit a coupling over the lip of a copper pipe, you need to make sure that the size of the pipe fits that of the coupling. For instance, if you need to fit a coupling over a pipe with a nominal size of ¼-inch, use a coupling with a nominal opening size of ¼-inch. Nominal sizes do not match the actual diameter of a pipe. To find the diameter of your pipe, measure its diameter and compare it to a nominal size chart. Or, simply measure the circumference of the outside of your pipe and purchase a coupling with the same measurements. Never try to fit a coupling smaller than a pipe onto the pipe.

Coupling Connections

• Couplings come with a variety of connection types. Connection type describes the way in which the coupling fits onto the pipe. For instance, a threaded coupling contains threads like a bottle cap. These threads screw onto similar threads on a pipe. To fit a threaded coupling over a threaded copper pipe, simply screw it on. Slip couplings contain no thread and simply slide over pipe lips. Because of this, a slip coupling must be of a larger nominal size than the pipe. Other types of couplings use bolts located opposite one another on the sides of the pipe to connect. To fit this type of coupling over a pipe lip, loosen the bolts, slide the coupling in place and re-tighten the bolts.

Slip Couplings

• Slip couplings contain neither threads nor bolts. This means that these couplings possess no means of forming a durable bond with pipes. Therefore, you must create that bond after installing a slip covering. This entails welding the slip cover to the lengths of pipe inserted at either end of the coupling. Use a lead-free solder and a handheld blow torch to weld a coupling to pipes. Heat one end of the coupling, holding the solder to the other end. When enough solder melts to cover the joint, switch ends and repeat the process.