Process fittings are components used to connect pipes or tubing and affect the flow of the substance being conveyed in systems in the pharmaceutical, food and chemical industries. How do process fittings work? Process fittings are made from different materials depending on their application. To connect pipes or tubes, they usually either screw on or use push-fit technology (depending on the type of pipe) rather than using solder. Push-fit technology allows for quick disconnection of the fitting without the use of tools. They are usually used with process tubing, which tends to be transparent so that you can see and note any blockages in the substance being conveyed. Types of process fittings. Process fittings can be made from different materials, such as acetal, brass, polyvinyl chloride (PVC), rubber and stainless steel. There are several different types of fitting that do different jobs. For example, tee fittings allow different pipes to converge, while reducer fittings allow for a change in pipe size to meet pipes or tubing flow requirements or adapt to existing piping of a different size. Different fittings have different maximum working pressure limits.