City Utilities (CU) is a municipally owned utility serving Springfield, Missouri. CU owns and operates two coal-fired generation units as well as a number of gas turbines and a landfill gas-to-energy project. In 2015, a lubrication management survey revealed many areas for improvement throughout the power generation facilities, including lubricant chemistry, cleanliness, testing, and lubricant storage and handling.
This quick test for ferromagnetic particles can be done in the field or in an onsite laboratory. Many commercial oil analysis laboratories use this same method. It is simple in the sense that it doesn’t take expensive or complex instruments. Although it is not quantitative, it is still very effective.
Of all the different types of gear configurations, worm gear systems are considered some of the most problematic because they present unique lubrication challenges due to their distinct design. To overcome these challenges, you must understand not only the complexities of worm gears but also which qualities to take into account when choosing a worm gear lubricant.
“After a number of return-line bearing samples were taken from our steam turbine, we were puzzled and concerned by some of the oil analysis results.
Our main concern was the large number of samples that showed elevated particle counts. It’s been recommended that maintenance personnel check the seals, breathers, etc. However, this leads us straight to the silicon count, which is, for the most part, zero. Therefore, the increase cannot be attributed to the ingress of normal dust or dirt. Neither does there seem to be any increase in any telltale wear metals or contaminants in the elemental analysis.
“Are there any warning signs of when a bearing is about to fail?”
Think of a bearing failure as happening in four stages. During the first stage (or earliest detectable point using vibration analysis), the signals will appear in frequency bands around 250 to 350 kilohertz (KHz). In the second stage, a signal around 500 to 2,000 hertz (its natural frequency) will begin to ring.
