Shell and tube (tubular) heat exchangers are used in applications where the demands from high temperatures and pressures are significant. Tubular heat exchangers are also used with fluids that contain particles that would block the channels of a plate heat exchanger. There are several types of shell and tube heat exchangers, including U-tube, straight, spiral, and finned tube.

The U-tube design consists of straight length tubes bent into a U-shape. The bundle is fitted with tube supports or flow baffles, depending upon the fluid outside the tubes. The tube assembly is placed in a shell to contain the fluid on the outside of the tube bundle. A head assembly is bolted to the shell to direct the fluid into the tube bundle.

To handle heavy fouling fluids or applications where temperature cross conditions exist, straight tube designs are available. (A temperature cross occurs when the fluid being heated has an outlet temperature that falls between the inlet and outlet temperature of the heating medium). Because of the straight tubes, the head assemblies can be removed and the tubes can be cleaned mechanically. Depending upon the tube sheet configuration (fixed or floating), the ability to handle large temperature differences between the fluids may be limited.