The oil sample in the photo is a from an outboard turbine bearing and the poor appearance raises a red flag. What specifically is the issue? What does the company need to do? What questions should they ask? Is a catastrophic failure imminent? Shutting down the unit is not an option.
By the way, it’s difficult to obtain a good oil sample from this unit. The unit holds very little oil that lubricates a critical bearing. Pulling a sample from the drain is the only option and shutting down the unit is not an option. You can argue that the lubrication design is flawed, but that won’t help you get a good sample in the immediate term.
What do we do to analyze the severity of the issue? Here is MRT’s recommended order of operations.
- Check for abnormal vibration and elevated bearing temperature.
- Review the maintenance activity on this unit from recent history – was there a recent, oil change, or bearing change.
- Review the oil analysis report for signs of possible equipment failure.
- Even though the sample is severely contaminated, often you can still determine whether contamination is due to abnormal equipment wear
- Check for elevated wear metals in the sample using emission spectroscopy.
- Also check for elevated magnetic debris using one or more of the following tests, Direct Read Ferrography, Ferrous Debris Meter, or PQ Index.
- Check for water contamination, and if elevated, look for any possible contaminant metals that can also be detected by emission spectroscopy.
- If possible, examine the visible debris in the oil sample under the microscope. But you need to be trained for the analysis to be useful. Depending on the results of the other tests, often a microscopic analysis is not necessary.
We found the following results with this sample:
- Abnormal vibration? NO
- Elevated temperature? NO
- Summarize the recent maintenance on the unit: The complete bearing housing was replaced three months ago, and the repair was urgent. There is a high likelihood that a proper system flush was not completed.
- Is there an elevated concentration of copper, lead, iron, or any other common wear metal? SLIGHT, not severe by any means.
- Did any other magnetic material test find an elevated concentration of ferrous debris? NO
- Is there water contamination? YES. There are visible water bubbles and Karl Fischer titration confirmed that the oil is saturated.
- Are there contaminant metals being detected in the sample? NO
- Microscopic evaluation? Not available, but probably not necessary. The debris looks like chips of rubber or paint and there are small particles that almost look like sand. But again, no contaminant metals including silicon are being detected, so probably not sand.
What do we do?
Fortunately, there is no indication of abnormal wear. Drain off more stagnant oil from the reservoir, then pull another sample for analysis. In fact, tomorrow I am driving over to the client to do this with them. There is stagnant debris and water in the reservoir, likely due to break in and since it’s unlikely that the new bearing housing was properly flushed, we need to get all of the break in debris out of there ASAP. Unfortunately, there is little oil in this circulating system, therefore we will likely have to install an external kidney loop filtration to remove the debris. Simply draining off more oil is unlikely to solve the problem and it could trigger a low-level lubricant alarm quickly. More to come, after pulling a sample tomorrow.