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what can cause a API 610 VS-6 pump shaft (2 stage pump) to seize in de brg housing? 1
- Thread starter hbk_mnm
- Start date
- Thread starter
- #2
More crystal ball gazing?
Lack of lubrication
Bearing life exceeded
Excessive up or down thrust
You said shaft is broken
You also the impeller is jambed, is it both?
From your post, the best thing to do is send it to the manufacturer or agent or pump repair shop.
Plus, please don't type in caps'
Photos always help, a manufactures drawing tells us nothing?
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.)
Lack of lubrication
Bearing life exceeded
Excessive up or down thrust
You said shaft is broken
You also the impeller is jambed, is it both?
From your post, the best thing to do is send it to the manufacturer or agent or pump repair shop.
Plus, please don't type in caps'
Photos always help, a manufactures drawing tells us nothing?
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.)
Let the guesses continue:
Upthrust is less likely because it is only two stages and the first stage is double suction.
I would add the possibility of over-lubrication.
The ball bearings are not identified. They could be a back-to-back pair of angular contact thrust bearings. If they were recently mounted, they could have excessive shaft interference or excessive axial crush on the outer races.
I also want to focus on the broken shaft. Excessive misalignment across the drive coupling.
Torsional resonance.
Gee. This is fun.
Johnny Pellin
Upthrust is less likely because it is only two stages and the first stage is double suction.
I would add the possibility of over-lubrication.
The ball bearings are not identified. They could be a back-to-back pair of angular contact thrust bearings. If they were recently mounted, they could have excessive shaft interference or excessive axial crush on the outer races.
I also want to focus on the broken shaft. Excessive misalignment across the drive coupling.
Torsional resonance.
Gee. This is fun.
Johnny Pellin
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1
- Thread starter
- #5
@Artisi
Impeller was not found jammed.
Shaft entering in the bearing housing from DE side was found free in rotation in contrast with the remaining shaft going outside of housing. The shaft seems seized only in axial direction as we are unable to dismantle and remove it easily.
Lubricating Oil quality and level was found normal.
Bearing inspection is not possible as we are damaging it in the process of removal.
My Theory - I guess the brass isolator got brushed onto the top plate and generated heat which led to the heating of the complete housing and weakening of the shaft ultimately leading to breakage in the housing. (Note : We saw the subject pump isolator red hot when the downstream pump got tripped on low suction)
Also it fused the bearing mounting sleeves also which is now hindering the removal of the parts inside.
But Why the isolator got rub against the top housing plate. is the question. axial movement? we are looking for signs of it.
Nothing found on the motor side though.
After dismantling nothing major observed.
I have attached some images. Hope it provides more insight and a possible different angle of view to finding the root cause.
Note : this pump was overhauled 15+ years back and is running at least 180 days yearly in a 1W + 1Standby config.
The bearings might have been replaced 4 or 5 years back as a preventive measure I recollect.
The trend of vibration was normal. (less than 1mm/s RMS)
@JJPellin
Yes the bearings are back to back angular contact type and we found all the lubrication parameters normal.
Past alignment reports were found OK (a year back, also we do check the alignment yearly).
Coupling was found OK.
Torsional Resonance. not sure about that.
Impeller was not found jammed.
Shaft entering in the bearing housing from DE side was found free in rotation in contrast with the remaining shaft going outside of housing. The shaft seems seized only in axial direction as we are unable to dismantle and remove it easily.
Lubricating Oil quality and level was found normal.
Bearing inspection is not possible as we are damaging it in the process of removal.
My Theory - I guess the brass isolator got brushed onto the top plate and generated heat which led to the heating of the complete housing and weakening of the shaft ultimately leading to breakage in the housing. (Note : We saw the subject pump isolator red hot when the downstream pump got tripped on low suction)
Also it fused the bearing mounting sleeves also which is now hindering the removal of the parts inside.
But Why the isolator got rub against the top housing plate. is the question. axial movement? we are looking for signs of it.
Nothing found on the motor side though.
After dismantling nothing major observed.
I have attached some images. Hope it provides more insight and a possible different angle of view to finding the root cause.
Note : this pump was overhauled 15+ years back and is running at least 180 days yearly in a 1W + 1Standby config.
The bearings might have been replaced 4 or 5 years back as a preventive measure I recollect.
The trend of vibration was normal. (less than 1mm/s RMS)
@JJPellin
Yes the bearings are back to back angular contact type and we found all the lubrication parameters normal.
Past alignment reports were found OK (a year back, also we do check the alignment yearly).
Coupling was found OK.
Torsional Resonance. not sure about that.
My initial comment would be "lack of lubrication"
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.)
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.)
- Thread starter
- #7
Seems like the drive key which was holding the shaft and bearing sleeve together got sheared off that led to movement and friction between both the components generating heat which cause the seizure and broken shaft.
timely inspection of weak components like keys and temperature protection system could have averted the failure
timely inspection of weak components like keys and temperature protection system could have averted the failure
Don't know that I agree with that analysis, why did the key shear?
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.)
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.)
I have seen a key like that in a similar pump fail repeatedly. We ended up finding that the pump mounting plate was distorted, causing the bearing housing to no longer be perpendicular to the shaft. This placed a bending moment on the shaft at the bearing housing. We had several dramatic failures before we figured that one out.
Johnny Pellin
Johnny Pellin
I don't see any sign whatsoever of any oil or trace of oil on the bearings and looking at the other photo's the amount of dirt and crud on and around the top the pump I would think the upkeep and maintenance of this pump was zero.
I'm staying with lack of lubrication as the cause of bearing failure.
What followed is the consequences.
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.)
I'm staying with lack of lubrication as the cause of bearing failure.
What followed is the consequences.
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.)
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