Large Double Suction Circ Water Pump

[stankap3]

I have a large 54" dia. double suction circ water pump that has had underfile removed from each vane by weld build up and grinding back to the orignal vane profile. The impeller vane in the area of the welds has 1/4" to 3/8" high lumps over a 6" x 3" area near the exit width. The impeller exit width is about 16" and vane thickness is about 1". The pump turns at 360 rpm. My question is:

Will the lumpiness of the weld repair cause hydraulic imbalance at this speed? Will it cause major performance issues? I was told by the repair vendor that the channels are so big that the lumpiness will little to no affect.

Does anyone agree, disagree, and why?

Thanks
Stan Kapushinski,
Systems Engineer

 

[vpl]

Will the repair vendor put his statement in writing with a guarantee?

(My two cents: If a vendor is not willing to back up the words with a written piece of paper, it's better to reject the part if you have questions about the workmanship.)

Patricia Lougheed

******

Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of the Eng-Tips Forums.

 

[Artisi]

Probably yes, also probably not measurable on an impeller of this size. Assume you are removing the underfile to reduce performance, will you compare flow / head / power with the old performance?

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[stankap3]

I'm trying to bring performance back to original specifcation. I checked power draw on all (4) CWP pumps today. We have two (underfiled at 463amps) and two non underfiled (one drawing 440amps, and one drawing 400amps). I am hoping the performance for this pump (underfile removed) is somewhere in betweeen the two non underfiled. My concern is that the shop that did it is realtively new to our organization. There website says they already worked on large ship impellers, large vertical turbines, a few boiler feed pumps, etc. I don't think they have dealt with much in the way of modifying hydraulics. The sales guys was the one who had the impellers underfiled and had the dwg of what was done add the undefile. Thing is, they were a little sloppy in adding material back on the impeller.

Thanks