Knowing how to bend pipe can be a very valuable skill. Professional mechanical pipe bending costs a minimum of £13, including the labour. Bending pipe yourself isn't difficult if you use the proper techniques. The pipe bender itself is a self-explanatory piece of equipment that can be obtained at a hardware store, and the process involves simple geometry and an understanding of degrees.
(Pipe benders come in a variety of sizes, to bend pipes of varying diameters. Make sure you buy the pipe bender that is correct for your size of pipe.)
Determine the proper degree of bend you need for the pipe. With a protractor, measure the old pipe's bend angle by placing the centre of the protractor's flat bottom on the centre of the bend, then measure the degrees of the bend angle. Getting the proper degrees for pipe bending is very helpful, but if you ask any mechanic or plumber, he will say he eyeballs every bend he makes.
Insert the pipe into the bender. The exact centre of the 180-degree half-circle is where the centre of the bend in the pipe will occur.
Leverage the bender and pipe against the ground. Slowly pull up the pipe bender arm while reading the degree the bend is at on the pipe bender's 180-degree scale.
Remove the pipe from the pipe bender once it is at the specified degree you need it bent to.
You will find a pipe-bending chart in most detailed car owner's manuals. These charts give the exact degrees of bends in various pipes throughout your car, such as the precise degrees of curves and bends needed to make the exhaust pipe fit. Most pipes bend with ease and don't kink at all. To make certain a pipe doesn't kink, tape one end shut, then fill the other end with sand and tape it shut, too. This applies outward pressure in the pipe while you bend it, and will prevent kinks.