Sticky Bearing 1

[Abualnassr]

Hi guys.

We were trying to check a centrifugal compressor's gearbox for any degradation. I've noticed that the journal bearings of this gearbox became very sticky due to oil, also the internal components of the gearbox were all very sticky.

What is the cause for this stickiness? ?

Knowing that the compressor has a lubrication system and the condition of the oil wasn't bad (nor good).

 

[romke]

it looks like the oil has deteriorated for whatever reason, resulting in the deposit of a sticky substance. what are you compressing? can the gas to be compressed come into contact with the lubricant?

 

[Abualnassr]

The compressed gas is Chlorine. And it is actually possible that Chlorine might leaked into the lube system somehow.

 

[Tmoose]

I'd send some of the oil for analysis.
I had a Renault with wet sleeves with a real small leak that let antifreeze/coolant into the oil.
After a batch of miles, some of the tappets would hang up and hold a few valves open until the engine warmed up a little.

 

[romke]

@Tmoose: antifreeze and engine oil can make a very sticky, shiny black combination that is able to freeze an engine when stopped.

@Abualnassr: chlorine is not a stuff that you would want in a lubricant. most lubricants would not be compatible with chlorine. i suggest you have the lubricant checked whether it has reacted with chlorine. if so, you will have to find out how it got there - which means you will have to check the bearing sealing system.

whatever the cause, you will have to clean out the mess thoroughly - and a careul check whether gears of the bearings of the gearbox for corrosive attack would be advisable.

 

[Abualnassr]

romke, actually the reason we checked the gearbox was the NDE bearing was leaking. And, you are right about the shiny black combination. But, what are the reasons that might cause this black combination ?!

 

[romke]

the reason for the sticky stuff is a chemical reaction between the lubricant and air where polymerlike substances may be formed. chlorine gas acts as a catalyst to speed up the oxidation proces. contact between chlorine and mineral oil based lubricants in gascompressors is usually avoided by design to prevent this happening. in centriugal compressors mechanical seals or labyrinth like seals are used, in reciprocating compressors the cilinder/piston part is usually separated from the other parts of the compressor and made from materials that can function without any lubrication at all.

since in your case the lubricant for the compressor bearings and the driving gearbox is the same, the sticky stuff has spread into the gearbox.

 

[Abualnassr]

That's actually what happened. Before we went to the check the gearbox, we had to change the carbon seal since it was leaking.

Thanks romke for putting it all together for me.

 

[diskullman]

Why don't you send some of the used oil out for analysis and find out for sure

Russell Giuliano

 

[Abualnassr]

diskullman, I sent the oil sample & I'm waiting for the results