Failure analysis of gas blower shaft of a blast furnace

Failure of a gas blower shaft of a blast furnace was analyzed. Investigation showed that the loosening of the lock plate was responsible for the shaft fracture. Examination revealed that the dislodgement of the lock plate resulted in constant rubbing of this component against the shaft leading to formation of grooves and loss of material from the shaft in localized regions. The fractographic features were completely obliterated due to post fracture rubbing and hence the micro mechanism of fracture could not be determined. However, analysis suggests that the failure of the shaft had occurred most probably by fatigue. The shaft failure was secondary in nature and had resulted subsequent to the primary failure, i.e., dislodgement of the lock plate from its position. (C) 2007 Elsevier Ltd. All rights reserved.