🔍 Key Concepts

• Tube sheet is the thick, flat plate that the ends of the tubes are expanded or welded into • Look for the place where many tubes appear to terminate in one solid plate, not the curved drum or the fan housing • Distinguish between the tube bundle itself and the structural sheets or headers that support and seal the tube ends

💭 Think About

• First, find the main tube banks in the illustration and trace where those tubes end or enter a solid plate • Ask yourself: which letter is pointing to the flat plate that closes off the ends of many tubes at once, forming a pressure boundary? • Eliminate any letters that point to rotating machinery, outer casing, or curved drums rather than a flat perforated plate full of tube ends

✅ Before You Answer

• Verify that the part you choose is a flat plate (not cylindrical) with many tube ends going through it • Confirm it is acting as a pressure boundary between gas side and water/steam side, not just as external boiler casing • Make sure you are not confusing the tube bundle (a group of tubes) with the tube sheet (the solid plate that holds those tubes)