Groove worn on wear ring surface at the eye of each impeller stage?

[GaTechTheron]

Experts,

I came acorss a pump with a radial groove worn on the eye-side wear ring surface at the eye of each impeller? The goove goes the whole way around the impeller.

I have seen this as a result of pumping abbrasive liquids, but never so pronouced. The groove almost looks like it was machined into the wear ring, and it almost goes the whole way through the wear ring. This happened on every wear ring. I have never seen this before and I'm stumped.

Hot Produced Water: ~180-190F.
Diffuser-Style Pump

Thoughts?

 

[Artisi]

Couple of photo's of the damaged and surrounding area would be nice.

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.)

 

[LittleInch]

Cavitation?

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[BigInch]

Normally pits, as opposed to "groves" and on each stage as well, but let's wait for pics.

Independent events are seldomly independent.

 

[JJPellin]

I'll take my turn and offer a guess. If the damage is on the stationary ring rather than the rotating, I would check to see if the axial alignment of the rotor within the casing was off. But, few facts could prove me wrong.

How many stages?
Do all the impellers face the same direction?
Is the damage on the stationary ring?
Are there very heavy, very abrasive particles present?


Johnny Pellin

 

[BigInch]

I'm already making up the stages. He said impellers, not stages.

Independent events are seldomly independent.

 

[GaTechTheron]

Gents,

http://files.engineering.com/getfil...101-9ca3-41345e77faa4&file=Impeller_Image.jpg

Note that by "wear ring" I meant "wear ring surface." These have "integral" wear rings.

Thanks,
Theron

 

[JJPellin]

This is a strange looking impeller. It looks like it is designed for a lateral (axial) wear ring. If it has both lateral and radial wear rings, abrasive solids could become trapped between the two. Or, perhaps it is designed for a lateral ring, but was assembled without it. That could create a dead zone that could trap solids.

Johnny Pellin

 

[Artisi]

"The groove almost looks like it was machined into the wear ring, and it almost goes the whole way through the wear ring. This happened on every wear ring."

Maybe it was designed that way.

Have you thought about contacting the supplier / manufacture?

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.)

 

[GaTechTheron]

Artisi-

Yes, andI'm told by the MFG that it was not designed this way, and that this was the result of sand passing through the pump. How could sand cause this and only minimally wear everything else?

 

[JJPellin]

Hard abrasives like sand can be trapped in certain locations within a pump and cause highly localized damage. I have seen cuts as deep as an inch into a head or seal chamber at the sharp corner at the bottom of the stuffing box. This was a trap location. I have seen similar deep, localized damage behind the stationary wear ring in a pump head. Because of centrifugal force sand particles that reached these points could not get out. They swirled around and cut deeper and deeper. I expect you are seeing a similar phenomenon. I would need to see a cross section of the pump to verify that this location is such a trap. With that said, I would expect the deep damage on the stationary part not the rotating ring on the impeller. But, this depends on the geometry in that location.

Johnny Pellin

 

[clay87]

Picture is too low resolution to tell...is the groove in a replaceable wear ring or in the impeller surface behind the wear ring?

 

[Artisi]

Also my thoughts, the photo' is just about useless, needs to be higher resolution, with close-ups and general views from various angles of the impeller / wear ring area, also a view of the case area where the impeller is situated wouldn't go astray. Looks as though where is also cavitation and or erosion corrosion in some areas, photo's would also help.

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.)