Managing Water in Rolling Mill Lubricating Oil

In our last post, Improving Rolling Mill Oil with Vacuum Dehydration, we discussed how the demulsibility (ability of the oil to separate from water) of oil is an important characteristic that greatly influences the effectiveness of the lubricant and how a loss of demulsibility can result in poorly lubricated bearings, unplanned downtime and premature fluid replacement. 

Benefits of Vacuum Dehydration for Rolling Mill Lubricant Oil

Steel mills typically use lubricants with high demulsibility for rolling mill back-up roller bearings and chocks since relatively high levels of water contaminate the oil from quenching and descaling processes. These rolling mill lubricant oils may be known as Morgoil as they are commonly used on Morgan rolling mill systems.

If the hydraulic, lubricating, compressor or gear oil you use is not made of a water base in formulation , then water is considered a contaminant and must be recognized and managed. 

There are three types of water in a typical system: free water , emulsified water and dissolved water. The water saturation point of most oil, that point above which water is in a free form, is 200-400ppm, depending on age and condition. 

Using 100ppm for an upper water limit for most systems using mineral base oils, this means all free and emulsified water and a significant portion of dissolved water must be removed.

A vacuum dehydrator is one of the very few methods to remove dissolved water from oil. Let's take a look at these three types of water in your system. It will give you a solid foundation for how the vacuum dehydrator works in the end.

At the end of Part 2, we discussed the winning nature of vacuum dehydration. If you missed Part 1 in the series, you can find it here. 

Did you know that hydrogen is the friendliest molecule - meaning that it is most likely seeking partners to attach to? Similarly, the suspended particles in oil actively look for particles to join forces, so they pair with the water. 

This particulate contamination is the catalyst guilty of continuing the degradation of the oil and the increase of emulsified water. The more water there is, the more oxidation that occurrs. This also increases various acids that form as the molecules break down. These acids attack seals, hoses, pumps and metal.

If you're just tuning in and didn't catch the first part of our steel mill and lube oil series, click here.

When we left off, we just determined how the high levels of emulsified water and high particulate contamination levels work together to cause bearing failure and reduce oil life. So, how do we prevent this expensive combination from happening? We're glad you asked!

Premium oils keep steel mills running. It's crucial to protect their quality in order to keep the mills fully functioning. 

In both hot and cold steel mill production, high-demulsibility lubricant is used for backup roller bearing lubrication. Some of these oils are referred to as SD, which stands for super-demulsibility. Not surprisingly, these SD oils are a premium product and come at a premium price. If a manufacturer wants to invest in these big-ticket oils, they obviously want to go to great lengths in order to keep them clean and fully functioning.

Join us for this three-part series as we take an in-depth look at improving rolling mill lube oil performance and useful life.