The Third Link in the Chain
In the previous articles in this series (which began in the May/June 2008 issue of Lubrication Management & Technology), the focus was on the first two links in the cleanliness chain: the lubricant blender and the distributor. In this installment, the authors look at the final link—the end user.
No study of oil cleanliness really would be complete without a look at what happens once the oil reaches the end user. Is that where the real trouble starts? To try to find out, we chose to examine two large plants, an oil refinery and a petrochemical complex. Both facilities have large populations of rotating equipment, including significant numbers of centrifugal pumps, electric motors and compressors. A large number of oil samples were collected from both plants and evaluated separately for viscosity, ISO Cleanliness and water by MRT Laboratories. The findings from each plant—or end user company—are as follows:
Oil refinery data
The large Gulf Coast refinery selected for this study has instituted a program requiring the delivery of clean and dry oil. Its requirement of 15/13/11 along with < 50 ppm of water for delivery of clean oil has resulted in improved bearing life. Table I illustrates the oil cleanliness findings from this refinery.
The results from the referenced refinery indicate that while there is a wide variation in oil cleanliness at the site— even for the same equipment types—overall, the cleanliness is not out of range. Several concerns, however, surfaced here.
1. The cleanliness rating of the oil in the ISO 32 bulk tank (21/18/15) was high for a centrifugal compressor, indicating that the fluid was too dirty for that service.
2. The oil from one reciprocating compressor was too dirty for evaluation.
3. The containers used to add oil to the pumps also raised concerns. The recommended sealed plastic containers utilized for this task contained very dirty oil (23/22/13). No matter how clean oil is when it is delivered, it can become contaminated very quickly if not handled properly. One bright note, though, was the dryness of the oil. No sample exceeded 50 ppm.
Although the results of this refinery evaluation were obtained from a small number of samples, they still provide useful data on the cleanliness of the oil in this facility. All sampling was observed by one of the authors. Collection was consistent with best practices to minimize the introduction of outside contaminants.
Petrochemical complex data
The second end user facility evaluated for this study was a large petrochemical complex that has no cleanliness requirements for incoming oil. Table II reflects cleanliness data collected at this operation. Our major focus in this plant was on the evaluation of lubricants in storage tanks and small containers used to add oil to pumps and small equipment.
Although samples from the tankage were found to be reasonably clean, those from containers used to add oil to pumps and small equipment were found to be very dirty. This strongly suggests that improvements in keeping oil clean in containers should enhance pump reliability.
Yes, the oil in the large equipment at the two end-user facilities evaluated for this study was reasonably clean. However, given the fact that the oil in some tankage and containers at these plants was not as clean as it should have been, these areas seem to be where real improvement efforts should be focused.
While cleanliness levels in samples from some of the large equipment at the two facilities could be attributed to filtration, end users should be mindful of the fact that it is vitally important to start out with as clean an oil as possible. Unfortunately, as illustrated by this study, clean oil delivered by a supplier can become seriously contaminated as a result of poor storage and handling practices.
One of the most important findings from this study is that everyone in the oil cleanliness chain—including you, the end user—has to take ownership in ensuring that clean oil reaches your equipment.
In addition to acknowledging the staff and management of MRT Laboratories for their work in the analysis of the oil in this study, the authors wish to thank the following individuals for assisting in the data collection for this article: John Gobert, Mark Kavanaugh, Jimmy Thomson, Bill Tummins and Russell Aucoin.
The concluding article in the series will summarize all the ? ndings from the blender, distributor and end user. Best practices to achieve oil cleanliness targets and enhanced equipment reliability, including utilization of mobile particle counters, will be discussed in detail.