There are two main ways of joining lengths of copper pipe together – with a compression joint which is fitted to the pipes using spanners or with a capillary joint which is soldered on to the pipes.
A compression fitting has a screwed body with a nut and sealing ring, called an olive, at each end. To make a joint, the pipe ends are pushed into the body and the nuts are tightened, squashing the olives on to the pipes to form a water-tight seal.
With capillary fittings, a watertight seal is made by melting sold so that it flows (by capillary action) and fills the small gap between the fitting and the pipe ends which are inserted into it. The type most suitable for the amateur plumber is the solder-ring ('Yorkshire') fitting which has its own, built-in supply of solder.
End-feed fittings are similar, but they do not have their own supply of solder. The pipes and fitting should be prepared in the same way as with a solder-ring fitting, and the joint heated. A length of solder wire should be melted at the mouth of the fitting and allowed to creep into the gap between pipe and fitting. As an alternative to using a blowlamp (or, for bigger jobs, a blowtorch), you can get electrically heated tongs that you apply to the pipe next to the fitting.
There are no strict rules about when to use capillary connections and when to use compression ones. However:
o Compression fittings are more expensive than capillary ones
o Compression joints are fairly easy to make but capillary ones require practice
o Compression joints are usually easy to undo and reconnect whereas capillary joints are permanent they may have to be sewn apart
o If a compression joint leaks after being made, the leak can usually be stopped by slightly tightening the fitting. A leaking capillary joint often means that the solder has not flowed properly. Reheating the fitting may stop the leak but it is illegally
o Compression joints can not be made in confined spaces where there is no room to use spanners. On the other hand, there are many places where a blowlamp is necessary for making a capillary joint can not be used without the risk of starting a fire or loosing other joints
o Capillary joints are much neater and less obtrusive.
There are many different types of fit¬tings with either capillary or compression joint ends: straight couplings for joining two lengths of pipe together in a straight line; elbows and bends for joining two lengths together at an angle (usually a right-angle); tees for joining a branch pipe; and adapters for joining pipes to taps.
There are also various push-fit fittings in both brass and plastic which have the advantage that the pipe can be rotated in the fitting after it has been made.
Some fittings, such as taps for garden hoses and washing machines, have a screwed end. These fittings can have different sizes of screw thread – Jin BSP (British Standard Pipe) is the most common. There are a number of ways of making a watertight joint with these fittings. The simplest is to wrap PTFE tape around the male thread before screwing it into the female part of the fitting. But PTFE tape will not seal large threads -like the ones on immersion heaters – or threads near central heating boilers. For these joints, smear a small amount of jointing paste on to the threads followed by a few strands of hemp (which looks like unraveled string) before screwing the joints together. Screwed fittings which may need to be undone – tap connectors, for example have a fiber washer to make the watertight joints.