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.

One of our V1S vacuum dehydrators was recently put to the test in a marine application with hydraulic oil contaminated by more than 2500 ppm of water. Did it sink or swim? Find out below.

The Problem: Failed Hydraulics Seal and Lost Productivity

When a seal fails on a net hauler hydraulics system out at sea, the costs and lost profits stack up quickly. In this instance, salt water began entering the hydraulic fluid on a 245 ft (75 m) purse seine through a seal leak, rendering the net hauler out of commission.

Faced with frequent fluid exchanges at a cost of $9,300 plus disposal, or worse, substantially larger lost profits from downtime for replacement of the seal, the vessel owner was in desperate need for a solution to allow him to continue operating without fear of malfunctioning equipment.

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.

Moisture contamination is inherent in the world we live in. In fact, it's all around us; that's what makes it so difficult when it comes to keeping water out of your oil.

The level of water vapor in the air is known as humidity. For example, If there is 80% humidity, the air contains 80% of the total amount of water vapor it can hold at the given temperature. Thus, there's always an amount of water in the air.

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.