In this week’s tip, we will talk about a problem that occurs in rotating machinery, which is oil leakage in sliding bearings. When they occur due to wear and/or seal failures, they are easily solved, but when there are other problems involved, their solution is not always so straightforward. The main causes of oil leakage in sliding bearings are generally associated with 4 factors: damaged parts, failure in the sealing system of the bearings, oil flow above the design recommendation, and a pressure difference between the bearing housing and the inside of the equipment.

As most cases of leakage are solved only by correcting the seals and adjusting the oil flow (adjusting the pressure and flow rate), we may be led to conclude that the solutions boil down to these actions. It turns out that this is not always true. There are more complex cases where the cause may be associated with the pressure difference between the bearing and its environment. Like wind in the atmosphere, which is the movement of air from a high pressure zone to a low pressure zone, lubricating oil also tends to make this movement if we have pressure differences between the bearing and its environment. In these cases, the solution demands a detailed analysis of the pressure levels in this region and how to act for its equalization.

External and internal visual inspection of the equipment, as well as monitoring the temperature of the bearings are recommended practices to identify oil leaks in the lubrication system. If the bearing lubrication is done through an oil ring, oil leakage will lead to the exhaustion of the reservoir, and significant damage to the bearing may occur due to loss of lubricating oil.

If the oil leaks, it can contaminate the winding and damage the insulating system, mainly because it carries other conductive dirt along with it. Periodic inspections are recommended by measuring the clearances of the components in the bearing sealing system, visual inspection of the assembly, and using the lubricating oil pressure and flow rate as specified by the manufacturer.

Contact our team and clarify your doubts about check items and evaluation in periodic preventive maintenance of your equipment.