Turbine Lube Oil

Shell Aviation

GE - Aviation: LM6000

In the samples you gave for testing, have you also given a sample of brand new, un-used oil? Is it completely sodium free? If it is, then the answer is simple. Wherever your lube oil circulates, there is a sodium containing contaminant. Shouldn't be too difficult to find what it is.

We've sent a sample of the fresh oil as well.

Waiting for the results.............................

Check your de-min water composition carefully. May have very minimum unnoticed sodium, and very fine leaks of water vapors to lube oil and final form sodium.

Is your gas turbine situated in a coastal location?

Yes, our main cooling water intake is from the Arabian sea.

But as I mentioned earlier, we are using De-min water for our internal cooling circuit.

I am not very familiar witht LM6000, but would suggest that if you are not gertting this from your cooling water you are probably contaminating your oil via the atmosphere in which you are working. Check the purging of oil sump, demister if fitted, bearing purges/buffer gas etc. Special attention to the air compressor bearings. You suck in that amount of sea air and get these things wrong you get salt in oil.

It can be that the sodium is used as an additive in lubricant to make a protective layer over the metals in the engine.

Do to the extreem heat of the engines combustion the oil evapotates and the sodium is left behind as a layer on the matel. This layer will protect the matels against the high tempertures.