1000 HP Worthington Pumps

[hec64]

My company installed three 1000 HP Worthington Pumps (ductile iron) in 1991. Ten years later we found that the pumps casing were corroded like the pumps were cavitating. We know the pumps were running within their curve limits and we know that this was not possible. We though it was a corrosion problem, but after further analysis, we could not find the cause of corrosion. We had another pumps station with 1000 HP Worthington pumps (1991) with different site condition but similar problems and we are guessing that it could be possible that the problem happen during manufacturing of the pumps. We could not prove this since at that time the company were sold to an Indian company and we have not been able to prove that during that time they did not follow proper manufacturing procedures. We contact the manufacturer but they do not have any records since the company has been sold several times. Does anyone has Worthington pumps from 1991- 1992 with similar problems? We just want to know if it is a manufacturing problem or something else.

 

[JJPellin]

You would probably get more replies by posting this in the Pump Engineering forum. Your terminology is confusing to me. You refer to corrosion damage from cavitation. I assume you mean erosion damage. I am not sure how cavitation damage could be badly damaging the case on a pump this large. We installed a 3500 HP Worthington pump in 1984. Ours was a 9 stage barrel pump in water service. We experienced two impeller failures within the first year despite the fact that we were running the pump within the manufacturer's recommended flow range. What we found was that they were not sufficiently conservative in calculating their minimum flow number. Because of the very high energy of the pump, the suction specific speed was high enough that we were experiencing suction recirculation cavitation. We replaced the impeller design with one that had a higher NPSH required (and thus a lower suction specific speed) and have had no problems since then. If you could give more details about you pump configuration, service and describe the location of the damage, I might be able to provide more meaningful comments.