What is the role of a tube sheet in a heat exchanger?

• A. It is a plate drilled to match the number of tubes
• B. It provides insulation
• C. It acts as a gasket
• D. It forms the shell boundary

Answer: (A)

The tube sheet is the mounting plate for the tube bundle. It is a flat plate drilled with holes that match the exact number of tubes in the exchanger, so each tube can pass through and be secured in place. This precise drilling sets the spacing and alignment of all tubes, and the tubes are typically welded or brazed into these holes, forming the end closure of the tube side and creating a stable, sealed interface between the tube side and the shell side. The other options describe roles that belong to other components: insulation is applied to reduce heat loss elsewhere, gaskets are used at flange or joint interfaces, and the shell boundary is defined by the shell structure itself, not the tube sheet.