1. Tubes: These are the primary heat transfer surface. They can be:

Straight or U-shaped (U-tubes): Straight tubes are fixed at both ends, while U-tubes allow for thermal expansion.

Made from various materials: Such as copper, brass, stainless steel, titanium, or carbon steel, chosen based on the fluid's corrosiveness, pressure, and temperature.

Different sizes and thicknesses: Specified by the required heat transfer area and pressure containment.

Finned: Sometimes they have external fins to increase the surface area for better heat transfer.

2. Tube Sheets: These are thick, round metal plates with precisely drilled holes. The tubes are inserted and secured into these holes. The tube sheet creates a rigid structure and, crucially, acts as a pressure boundary, separating the shell-side fluid from the tube-side fluid.

3. Baffles: These are plates placed inside the shell, along the length of the tube bundle. Their main functions are:

Support the Tubes: Prevent the tubes from sagging and vibrating excessively, which can lead to failure.

Direct Shell-Side Flow: They force the shell-side fluid to flow across the tube bundle in a zig-zag pattern, instead of taking a straight, short path. This cross-flow greatly increases heat transfer efficiency by creating more turbulence.

4. Tie Rods and Spacers: These are used to hold the baffles in their correct positions along the length of the bundle.

5. Channels/End Caps: These are attached to the tube sheets and direct the tube-side fluid into and out of the tubes.