thread407-509102 Reference this th

[Emenent1999]

thread407-509102
Reference this thread, now we have faced 8th big end bearing failure.
Can anyone provide details how Cavitation can be verified if there is any. As the other two pumps has same parameter but failure is being observed only in one

Also comment on the Babbitt of the bearings. Previous or old se bearings have ASTM Babbitt Grade 2 while new bearings which are failing have Babbitt Grade 3

Grade 2 Babbitt has high toughness due to low copper and high tin
Grade 3 Babbitt has high hardness due to relatively high copper and low tin

 

[3DDave]

Are there high velocity blades moving through steam in this pump?

So far it seems mainly like oil starvation or the wrong oil is used for lubrication. Melting and tearing out flakes is from metal-to-metal contact.

It would be more likely there is a potential difference because of bad grounding that is conduction (not discharging) electrical current through the bearings. So far the view into all of this is like looking through a drinking straw, so understanding is tough to do.

The start of "The pump is a quintuplex pump" should have continued with Model number made by Pump Company Name.

Photos of the entire installation, details about how much the pump is run; these could be helpful to know about possible differences between this pump and the ones that don't fail.

 

[btrueblood]

In addition, I'd like to know if this pump's oil reservoir runs higher in temperature than other pumps, runs more hours, starts more often, has a lower oil pressure...

 

[Emenent1999]

I was having a conversation with a person on LinkedIn. I told him the clearances of the bearings.

Main Bearing Journal Shaft OD is 450 mm
Clearance is 0.36 - 0.60 OEM Recommended

Big End Bearing Journal OD is 255 mm
Clearance is 0.2 - 0.45 mm

The person told that this is excessive clearance the Recommended clearance should be in Range 0.8 -0.9 X Shaft OD/1000.

According to it the big end bearing max clearance allowed comes out to be 0.22 mm and we are operating it above this normal clearance is 0.3 mm of Big end bearing.

According to him this causes impacting on the bearing due to which bearing fails

Anyone like to add to this comment?

 

[Emenent1999]

Replying to above question the lube oil pump temperature and pressure of all 3 pumps is same.

And all 3 pumps are in continuous operation and don't stop

 

[Emenent1999]

 

[Emenent1999]

Attached are the pictures showing main bearings and big end bearings arrangement

 

[Emenent1999]

Seems like the discussion has stopped. Please provide more inputs if any....

 

[FMJalink]

Emenent1999,
Do not know whether you solved the problem, but if not, I would advise to investigate what changed before start of the problems to the problem pump, its lubrication system, its own pump system, the lubricant and the medium pumped.
Having 2 fine running pumps, what is now different with the problem pump when compared to the fine running pumps?
Somehow the lubrication film in the bearing appears to be failing temporarily. Could be due to not sufficient oil at the bearings, high pressure spikes in the pumping or a change in bearing design.
Good luck with solving the problem.