Tube, or more precisely tube, is one of the most important components of heat exchangers, which is responsible for providing the surface needed for heat transfer between fluids. Heat exchanger pipes are usually made of carbon steel or steel alloys. Nickel, titanium or aluminum pipes are usually used for special applications. Precision seamless pipes are made by cold drawing method.

The outer surface of the shell and tube heat exchanger tubes is of the plain or fin type. The finned tube is used for fluids with very low heat transfer coefficient. The surfaces of this tube increase the heat transfer area of the fluids by two to four times more than the surfaces of plain tubes. The diameter of the shell and tube heat exchanger tubes is usually 16 mm, 19 mm and 25 mm. It is also possible to use smaller pipes of this size. However, the smaller the diameter of the pipe, the more difficult it will be to clean.

Larger diameter pipes are used to facilitate cleaning or reduce pressure drop. The wall thickness of the shell and tube heat exchanger tubes varies between 1.65 mm to 2.77 mm. Low thicknesses are chosen when using pipes made of relatively expensive materials (such as titanium). The set of tubes inside the converter is called a bundle.