Failure analysis of a blower fan at a petrochemical plant

The catastrophic failure of the main blower of a petroquimical plant boiler is discussed. The preliminary analysis of all the damage suffered by the machine indicated that the rotor was subject to strong unbalanced forces due to the breakage of one or more blades. Root Cause Analysis (RCA) was employed to determine the events responsible for failure. It could be established the bearing box nearest to the gearbox was damaged first, and the consequent displacement that was transmitted through the coupling, tore the gearbox out of its base. The reconstruction and analysis of the deformations of the analyzed parts allowed identifying the initiation of the fracture at the cone rotor. Manufacture defects contributed to the occurrence of the failure due to an excess rotating speed overload.