4th Class Power Engineering Part B Practice Exam

Boiler tube failures often occur due to various reasons, with corrosion and overheating being significant contributors. When boiler tubes experience high temperatures beyond their design limits, the metal can weaken, leading to structural failures. This overheating can happen due to factors such as flame impingement or insufficient water flow, which raises the metal temperature excessively and causes the tubes to warp or rupture.

Corrosion, on the other hand, can be caused by water impurities, improper water treatment, or the presence of oxygen or other corrosive agents in the boiler water. Over time, this corrosion erodes the tube material, creating weak points that can ultimately lead to tube failure.

In contrast, excessive water levels can cause operational issues but do not directly lead to tube failures as we see with corrosion and overheating. Insufficient steam generation generally indicates other operational problems but does not typically result in tube failure directly. Lastly, too much air intake may affect combustion efficiency but is less likely to directly cause tube failure compared to the damaging effects of corrosion or overheating on the tube materials themselves.