One of the advantages of domestic copper pipe is that it’s easy to cut and bend. Few tools are required and even if you’ve only a few bends to make in a pipe run, it makes sense to know how it’s done. Making accurate bends may need some practice, but it’s cheaper than buying specially-shaped fittings.
In all plumbing water has to be carried from a source to a fixture and often then to some type of exit where it can disperse as waste. Basic to all of this is that water must run smoothly with nothing causing resistance to the flow — an important factor when the pressure is low. Generally the best plumbing practice is to make pipe runs as straight and direct as possible. But sometimes bends are unavoidable (like, for example, when pipe has to go around a room or to turn down into an area below) and if available fittings are neither right for the angle nor attractive to look at, then you’ll have to bend the pipe to suit.
Copper piping, because it is both light and resistant to corrosion, is a popular choice for home plumbing work. It can be joined with either capillary or compression fittings and when bends are needed you can create the angles in several ways. The first essential is to accurately work out the pipe lengths you require. Once you’ve made the measurement double check it — it’s quite easy to forget to allow for the pipe that will fit into the socket ends of the joints. You can make the actual marks on the pipe with pencil as this is clearly visible on copper and is a good guide when you come to cutting.
Cutting pipe accurately
For smaller pipe sizes, a sharp-bladed hacksaw is the best tool to use to make the cut. You’ll need to hold the pipe firmly, but if you use a vice be careful not to over-tighten the jaws and crush the bore of the pipe. It’s important to cut the pipe square so that it butts up exactly to the pipe stop in the joint. This will ensure the pipe is seated squarely in the fitting which is essential for making a watertight seal. It will also help to make that seal. It’s surprising how near to square you can get the end just cutting by eye. But the best way to make a really accurate cut is to use a saw guide. This can be made very easily by placing a small rectangle of paper round the pipe with one long edge against the cut mark. By bringing the two short edges of the paper together and aligning them you effectively make a template that’s square to the pipe.
All you then have to do is hold the paper in place and keep the saw blade against it as you cut. Any burr that’s left on the cut edges can be removed with a file. If you intend to carry out a lot of plumbing, or are working mainly in the larger pipe sizes, it may be worthwhile buying (or hiring) a wheel tube cutter. Of course using one of these is never absolutely essential, but it does save time if you’ve more than, say, half a dozen cuts to make. And once you have one you’ll use it for even the smallest jobs. It’s quick to use and will ensure a square cut without trouble every time. You simply place the pipe in the cutter and tighten the control knob to hold it in place. The cutter is then rotated round the pipe and as it revolves it cuts cleanly into the copper. This circular action automatically removes burr from the outside of the pipe, but burr on the inside can be taken away with the reamer (a scraping edge) which is usually incorporated in the tool.
Bending copper pipe
If a lot of changes of direction are necessary in a pipe run it’s cheaper and quicker to bend the pipe rather than use fittings. This also makes the neatest finish particularly if the pipework is going to be exposed. Under a pedestal wash-basin, for example, the hot and cold supply pipes rise parallel to each other in the pedestal before bending outwards and upwards to connect to the two tap tails.
Using fittings in this situation would be more costly as well as possibly being unsightly, while the cheaper alternative, making bends, means the pipework is less conspicuous. The pipe can also be bent to the exact angle required so this method of changing direction is not limited by the angles of the fittings. And with fewer fittings in a pipe system there are fewer places where leaks can occur.
The smaller sizes of copper pipe, those most commonly used in domestic plumbing (15mm, 22mm and 28mm), can be bent quite easily by hand. The technique of annealing — heating the pipe to red heat in the vicinity of the bend to reduce its temper (strength) and so make bending easier — is unnecessary when working in these pipe sizes. But you will need to support the pipe wall, either internally or externally, as the bend is made. If you don’t you’ll flatten the profile of the pipe. Using it in this condition would reduce the flow of water at the outlet point. For small jobs a bending spring is the ideal tool, supporting the pipe internally.
It is a long hardened steel coil which you push into the pipe to the point where the bend will be made. It’s best used for bends near the end of the pipe, since the spring can be easily pulled out after the bend is made. However, it can be used further down the pipe if it is attached to a length of stout wire (which helps to push it into place, and is vital for retrieving it afterwards).
Bending techniques
You actually bend the pipe over your knee, overbending slightly and bringing back to the required angle. The spring will now be fixed tightly in the pipe and you won’t be able simply to pull it out. However, its removal is quite easy. All you have to do is to insert a bar — a screwdriver will do — through the ring at the end of the spring and twist it. This reduces the spring’s diameter and will enable you to withdraw it. It’s a good idea to grease the spring before you insert it as this will make pulling it out that much easier.
Slight wrinkles may be found on the inside of the bend, but these can be tapped out by gentle hammering. It’s wise not to attempt this before taking out the spring. If you do you’ll never be able to remove it. Bending springs are suitable for 15mm and 22mm diameter pipe. But although it is possible to bend 28mm pipe as well, it’s advisable to use a bending machine instead. This is also preferable if you have a lot of bends to make. And if you don’t want to go to the expense of buying one, you can probably hire a machine from a tool hire shop.
A bending machine consists of a semicircular former that supports the pipe externally during the bending operation and a roller that forces the pipe round the curve when the levers of the machine are brought together. The degree of bend depends on how far you move the handles.
Flexible pipe
This is a kind of corrugated copper pipe which can be bent easily by hand without any tools. You can buy it with two plain ends for connection to compression joints or with one end plain and one with a swivel tap connector for connection to a tap or ball-valve. As it’s the most expensive way of making a bend, it’s not cost effective to use it when you have to make a number of changes of direction in a pipe run. It’s not particularly attractive to look at so it is best used in places where it won’t be seen. As such it’s most commonly used for connecting the water supply pipes to the bath taps in the very confined space at the head of the bath. And it can make the job of fitting kitchen sink taps easier, particularly when the base unit has a back which restricts access to the supply pipes.