When you're involved in a plumbing, heating, ventilation, air-conditioning or other project, you may find it necessary to bend piping to get the fit needed. Pipe bending allows an angle without using a fitting and it also saves you time by eliminating the need for cutting, soldering or refitting. Also make arcs or curves when you don't need sharp angles. The technique you use depends on the material you have; copper piping is usually the softest and easiest to work with, while aluminium pipes are harder and can possibly break. Bending can be done either by hand or with the help of a pipe bending tool.
Examine your materials and decide on a process. Before deciding which method you want to use (the main ones being compression bending and draw pipe bending), determine if you need to use a hot (induction) or cold process. Depending on the pipe material, decide if it's best to use a manual or automated process.
Although cold bending can be used on soft materials like copper, the induction method helps reduce labour and potential damage during testing to determine the correct angle. Cold bending usually requires a hydraulically-driven unit, while hot bending can sometimes be done manually with a bending slab or wrinkle bender.
Construct a template and pre-fill pipes with sand. Always prepare a template from wire or flexible tubing that represents the exact angle needed, use this to mark the bending point and guide you during the process. If you're using hot bending, fill the pipe with dry sand beforehand to prevent the heel, or outer edge of the pipe from flattening during bending (especially in copper or other soft metals).
Place a tapered wooden plug in one end, pack the entire pipe with sand and plug the other end. To control flattening or wrinkling in stronger materials like aluminium or steel, plan to over-bend and then return the pipe to its proper angle.
Use the bending tool properly. The bending tool consists of three main parts. The clamp die holds the pipe in place, the bend die provides a stable fulcrum for the pipe to bend around and the pressure die forces the pipe around the bend die.
Before you begin, add a little lubricant to the dies and check on the correct back pressure setting for the material type. To prevent wrinkling, use a wiper die that attaches to the bend die and guides the bend more gradually. Ensure you are using the right size dies for the job.
During hot bending, always wear asbestos gloves. Never increase back pressure above 700 PSI. Worn out bushings (the metal sleeves that hold screws) can cause dies to be unstable and affect bending.