Metallurgical Analysis of Fatigue Failure in Submerge Chain Conveyor

Abstract

Ash handling unit is one of the crucial part of the operation of a coal fired power plant (CFPP). This paper focused on the investigation of shackle chain failure in ash handling unit of a 600 MW CFPP. The failure caused disruption to the operating system of the CFPP. To improve the chain system in order to prevent similar failure in the near future, the metallurgical failure analysis was conducted on failed shackle chain through crack observation using optical and electron microscope and Vickers hardness test. Crack surface observation of failed shackle chain using Scanning Electron Microscope (SEM) revealed that the failure of shackle chain was primarily due to the fatigue failure which was proven by the presence of beachmarks. In addition, there were two initial cracks which were caused by pitting corrosion. The clearance (gap) occurred in the bolt connection system caused the fatigue load which in turn resulted in failure to the CFPP operation. This research suggested preventive measures to be taken to avoid similar problem in the future.