Determining the Cause of High Phosphorus Levels in Turbine Oil

Noria Corporation
Tags: oil analysis

"When we drained one of our turbine oil filter housings, inductively coupled plasma (ICP) elemental analysis showed phosphorus levels at about 1,600 parts per million (ppm), which is abnormal. The acid number was approximately 0.29. Do you have any insight as to what could be causing the high phosphorus levels?"

Phosphorous commonly comes from anti-wear (AW) additives, and a concentration of 1,600 ppm would indicate that the lubricant has a highly additized AW formula.

Your first step should be to verify that the phosphorus level is higher than the new lubricant’s concentration. If it is, this would suggest that there is contamination in the lubricant. You then would need to research all the possibilities to find the root cause of this contamination. The following is an example of the type of analysis that could be performed:

Hypothesis #1: The lubricant used in the machine was contaminated with another lubricant containing anti-wear additives or an STP-type additive that was added to the lubricant in use. This would have resulted in cross-contamination of the lubricant in service.

Hypothesis #2: The oil sample was taken from another sump, container or reclaiming system that contained another lubricant or additive. In this case, the lubricant might have been contaminated when it was transferred to the other system or container.

Hypothesis #3: During the sampling procedure, the oil sample was contaminated with some remaining lubricant or additive that was in the sampling device or bottle.

Hypothesis #4: The oil sample actually was from another lubricant and was simply mislabeled.

Hypothesis #5: There may have been a reading or reporting error by the laboratory. Double check with the lab to ensure that the phosphorus value is correct. Laboratories commonly hold the remaining sample for several days, so it may be possible to have the test run again. 

Hypothesis #6: The lubricant or oil sample was contaminated with a chemical, raw material or product existing in the plant.

Hypothesis #7: The new lubricant may have already been contaminated when it was delivered by the supplier. While this possibility is somewhat rare, it should still be considered as part of the investigation process.

Some research will be required in each of the above scenarios in order to determine the root cause of the contamination and so the appropriate corrective and proactive actions can be taken to eliminate any recurrence.  

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