Wilson Snyder Descaling
Application: Descale for Flat Products Rolling Mill
Pump Details: Wilson Snyder MBD 6-Stage
Pump Type: Multi-Stage Horizontal Split Case
A mill's descaling pump was cycling from full to low flow several times per hour depending on the mill rolling rate. When the vibration became excessive, the pump experienced thrust bearing failure.
Inspection revealed several problems. Due to improper material hardness, the bores had galled from contact with the impeller hub rings. The hub rings had also separated from the impeller hubs and were seized inside the case bushings. The bore ID appeared to have a hard coating, but there was galling on the surface. Hydro found that the coating could be machined, which would suggest softness unlike usual hard coated surfaces.
Hydro replaced the existing impeller rings with new heat treated rings made with greater hardness. The IDs of the impellers were chrome plated to eliminate any galling tendencies. To provide a better fit between the element and casing, the casing bore was welded and re-machined.
Before Hydro’s engineered repair, the pump was being sent out for repair every two years. A lesson learned from this engineered repair is that use of proper material is a key factor in quality repair practices.