Failure analysis of the multistage de-scaling pump impeller of the hot strip mill plant

Arbind Kumar Akela, Devaraja, Rameshwar Sah, Suraja Yekkar
International Research Journal of Engineering and Technology   unpublished
Premature failure of the multistage descaling pump impeller of hot strip mill (HSM) has been investigated. The multistage centrifugal pumps are used in hot strip mill for a large variety of applications, such as roll cooling, strip cooling at run-out table and de-scaling. The impeller is a single piece casting of martensitic stainless steel. The impeller rotates at 4800 rpm with a volumetric flow of 400 m 3 /hr of flue water with a discharge pressure of 185-210 bar. The premature failed
more » ... ture failed impeller has been thoroughly investigated to find out the root cause of the failure. The investigated includes visual examination, chemical analysis, hardness measurement and optical microscopy and electron probe micro analyzer (EPMA).Visual examination of the failed impeller indicated that the crack originated at the vane curvature and the presence of fatigue. The purpose of the investigation was to find out the root cause of impeller blade failure and suggest possible measures, to avoid the failure in future. The investigation results revealed that erosion, fatigue stress and material degradation were found to be the prominent reason for the impeller failure.
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