Hi!
We have observed frequent oil seal failures in I/P and O/P shafts of Flender Gearbox. The oil analysis report show high TAN value approx 4.5.

Can this high TAN value contribute toward seal leakages?

Regards

Seemant

What type of seal is it?

CR seal.

Thanks

Sorry, what does CR stand for?

This message has been edited. Last edited by: Josh,

It is Chicago Rawhide (CR) from SKF.

Material might be nitrile.

Regards

Seemant

Have you checked what damages on the oil seal?

Seemant,

High TAN is indicative acid buildup in the lubricant, as a result of oxidation and temperature escalation. Along with TAN increase, you should also see viscosity rise and in worse cases lacquering/sludge formation may occur. Depending on severity, all of the above conditions can damage the Gearbox seals. You say the gearbox seals fail frequently, apart from lubricant condition, check the nature of failure, eg. extrusion type..does the failed seal feel kinda soft compared to unused one or if the failure resembles 'cut/tear'.
Depending on the nature of failure, it could be induced by poor lubricant condition and/or alignment/clearance/backlash faults.

Cheers....Rajan

No Josh! I could not feel the seal failure but it was reported to us that within few months of putting new seal, it starts leaking. Also the oil change has not occurred for a year or so.

Thanks Rajan, do you have any experience of such failure? But one thing is quite certain, this high TAN no may not tear the seal but it certainly can soften the seal material and cause leakage. What do you guys think? Am I corrct?

Regards
Seemant

Yes, Seemant I've seen similar seal failures due to high TAN and temperature. U R right the seal will become soft in this case and clearance/misalignment induced failure will result in fractures of seal components.
Remember that the oil condition may be part of the cause for the leakage, others could be poor installation practices (dirt introduction/ ingestion)...thorough investigation is recommended to identify the root cause.

Good Luck...Rajan

What next, change lubricant type used?

I think complete oil change will help.
In process industry it might not be always possible/economical to change oil strictly in safe TAN limits. What is the extreme TAN no. for mineral oil before such problems occur?

Regards