Exam Question

### (a) Possible Causes of Leakage at Tube/Tube Plate Connection (6 Marks)
Persistent leakage at the tube-to-tube plate connection in a waste heat boiler is a serious issue stemming from several underlying causes, often acting in combination. These include:
1. **Waterside Corrosion and Pitting**: This is a primary cause resulting from improper boiler water management.
* **Mechanism**: The use of poor quality feed water with high levels of dissolved oxygen, low pH (acidic conditions), or high chloride content leads to electrochemical corrosion. This creates localized pits and general wastage of the tube material, particularly at the high-stress area of the tube-to-plate joint.