Exam Question
Where a waste heat boiler is subject to persistent leakage at the tube / tube plate connection, suggest with sketches, methods of effecting a permanent repair. (16)
Class 4 (4th Engineer)
MEP
📅 Aug 2024
Reference Answer
### 1. Introduction and Initial Assessment
Persistent leakage at the tube/tube plate connection of a waste heat boiler is a serious issue indicating a potential systemic problem rather than an isolated failure. The primary causes for such failures include:
* **Thermal Stress & Cycling:** Frequent and rapid changes in exhaust gas temperature and steam demand cause differential expansion and contraction between the tubes and the thicker tube plate, fatiguing the joint over time.
* **Vibration:** Engine-induced vibration, particularly if operating in a barred speed range, can be transmitted to the boiler, causing mechanical fretting and loosening of the expanded joints.
Persistent leakage at the tube/tube plate connection of a waste heat boiler is a serious issue indicating a potential systemic problem rather than an isolated failure. The primary causes for such failures include:
* **Thermal Stress & Cycling:** Frequent and rapid changes in exhaust gas temperature and steam demand cause differential expansion and contraction between the tubes and the thicker tube plate, fatiguing the joint over time.
* **Vibration:** Engine-induced vibration, particularly if operating in a barred speed range, can be transmitted to the boiler, causing mechanical fretting and loosening of the expanded joints.
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