11 replies to this topic

Hello everyone,

We have got a damaged impeller back from the customer after operating for more than 30 years. It is a centrifugal lube oil pump and rotates with 3000 rpm. There is a missing piece at the leading edge of a blade. For me it seems to be a forign object hit the impeller or cavitation. Please give your invaluable ideas of the possible causes. I have attached the pictures here.

Please let me know if you need any more info.

Attached Files

•  DSC06830.jpg   2.05MB   44 downloads

[Qalander (Chem)]

Dear vlt2009 Hello/Good Night,

Your attached pics could not be seen;instead only one image(picture) of impeller was seen.Thus the suggestion(s) will be not analytical and conclusive as such.

Just a single comment right now; since the impeller operated at 3000 rpm for the last 30 years possibility of material fatigue can not be ruled out however the detaching of piece seems a recent event as appears from the pic.

Hope this helps you in some way,but

more pictures,

service of the pump,

possibility of over speeding,

possibility of foreign materials,larger/harder particles association into pumped fluid etc.

may further help in proper analysis and problem solving,please appreciate.

[riven]

If a foreign object hit the pump (what is the service?) I would expect much more damage and different type of damage. I would expect far more deformation and benging on the leading edges of the break similar to what a puncuture hole would look like. So my guess is also stress related failure.

Find out how likely it is that a foreign object could have entered the system.

Edited by riven, 30 October 2009 - 07:03 AM.

[VikingUK]

If a foreign object hit the pump (what is the service?) I would expect much more damage and different type of damage. I would expect far more deformation and benging on the leading edges of the break similar to what a puncuture hole would look like. So my guess is also stress related failure.

Find out how likely it is that a foreign object could have entered the system.

I agree, the damage is too localised to be caused by a foreign object. You would expect damage across the entire impellor. But without seeing it up close I could not conclude. Look stress related to me.

[fatimah]

Hi vlt2009

didnt your client find anything when they disassamble the pump? if let say you have any strainer after the pump, you may check from there. the foreign material probably was trapped there.

[ankur2061]

In one of my commissioning experiences, a centrifugal pump impeller failed in a similar manner because a 5 foot length of steel wire re-inforced rubber hose was found badly mangled in the pump casing. We were actually able to take out the mangled length of hose. There was nothing we could do, except go for replacing the complete impeller. What does this tell you? PROPER SUCTION SCREENS ARE A MUST DURING COMMISSIONING. The lesson was learnt the hard way.

Regards,
Ankur.

[AKsrey]

Is it possible that the oil became contaminated with water or a process fluid ? This might lead to a highly localized failure due to corossion.

[Qalander (Chem)]

Dear vlt2009 Hello/Good Afternoon,
No follow-up, updating feedback from your end!
Is everything resolved, settled down or should we consider this a futile work any further?
Please be kind to provide some info!

[VikingUK]

Could whoever has given me a minus point on my reputation for this post please explain why ??

[ankur2061]

Could whoever has given me a minus point on my reputation for this post please explain why ??

VikingUK,

I did not give you a minus rating, which was really unjustified but I have removed the minus rating.

Regards,
Ankur.

[Qalander (Chem)]

Could whoever has given me a minus point on my reputation for this post please explain why ??

Dear VikingUk Hello/Good Evening,

Neither I gave any -ve rating to you nor to anyone else.

However you have not deserved any minus rating rather plus wherever possible may be given.

[ankur2061]

Could whoever has given me a minus point on my reputation for this post please explain why ??

VikingUK,

I am also a victim of somebody voting me down & I also don't know why because my post has neither been offensive to anybody nor it is irrelevant to the topic.

Regards,
Ankur.