On one of our turbine-compressor trains we recently experienced what appears to be a sludging or coking in the oil. The oil is a ISO 32 turbine oil and the mechanics reported what appeard to look like a large "cow pie" in the bottom of the gearbox. This was a blob of dark brown congealed lube oil. Anyone witnessed this before or have any ideas of what causes this? All the lube oil samples look good, no reported anomalies.

Fritz,
What you've described, to me it doesn't appear to be due to coking. It more likely hints to a contamination of a sort. Maybe your oil got contaminated with some grease, or there is some water solidifying and precipitating some sludge. Best thing is to scup some of that cow cake and send it to a lab. The analysis results may shed some light to it, and help with determining the origin.

I concur with John’s comments. I have seen this type of deposit before in turbine oil. After analysis we determined that it was an additive that had dropped out of the oil. Depending upon what gasses are present in your process, there may be some incompatibilities with part of the additive system. FTIR, Spectro would be good initial tests to run.

John/Greg,

Thanks for the reply, next time we come across this I'll have our mechanics pull a sample for the lab.