Possible Defects in Boiler Furnace:
Sludge deposits continue to be the prime cause of non-operation of internal controls and overheating of a furnace in a vertical boiler.
Overheating distortion on the furnace crown is mainly due to a deposit of oil, scale, or sludge on the heating surface or due to water shortage. The lower section of the crown causes overheating distortion due to the sludge deposits.
The furnace connecting to the shell may have welding cracks due to rapid fluctuation of thermal and mechanical stress, the results of improper starting up or shutting down procedures.
Direct flame impingement resulting in deformation of the crown or a local bulge in wall tubes opposite the burner opening is also possible.
Dry cracks in the furnace mouth, crown, or the furnace tubes caused by flame impingement are possible due to scale encrustation at the water side and forcing of the boiler. Areas suffering from poor circulation or relatively uncooled area are also susceptible to the above failure.
Deep cracks in the furnace mouth, crown, or furnace tubes caused by flame impingement are possible due to scale encrustation at the water side and forcing of boiler. Areas suffering from poor circulation or relatively uncooled areas are also susceptible to the above failure.
Deep cracks on plating should be stopped by drilling a hole at each end, opening up, and then welding.
Indifferent feed water may cause pitting of the furnace crown. A careful examination through the bottom manhole door would require detecting the above grooving.
Brickwork protecting the foundation, if damaged, may cause distortion of the bottom plating underneath the furnace. Damaged brick wok need to be removed to inspect the bottom plating for distortion before repair s to the brick work is carried out.
Corrosion: Any sign of corrosion on plating should be chipped clean and brushed clear. It is also possible to build up the weakened areas by means of electric welding. Pitting arear are difficult to protect from further corrosion due to the difficulty in maintaining the protective magnetic oxide layer