Second flue gas pass pipes collapsed due to boiler operation with very low level due to level control failure.

Flue pipes can become completely clogged due to poor combustion. Soot buildup on the surfaces of a boiler reduces heat transfer, impairing thermal efficiency and increasing fuel consumption.

This type of corrosion is caused by excessive localized concentrations of alkaline salts in areas of high thermal loads.

This other type of corrosion occurs when there is a very high level of dissolved oxygen in the boiler water. These conditions usually occur when the boiler is fed with water at low temperatures (below 80ºC).

A high concentration of iron in the form of rust inside the boiler is usually due to carry-over of this material from the steam or condensate return pipes.

This is a very common defect in boilers with poor feedwater treatment or inefficient blowdown regimes. The salts dissolved in the water are deposited on the outside of the flue tubes, firebox and any boiler component in contact with water.