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.
High-quality rolling mill oils are similar to turbine oil in that they are made from high-quality base stocks and contain little to no additives. Demulsibility describes the fluid’s ability to separate from the water that gets into the lube oil. If the fluid has high demulsibility the water will quickly separate from the lubricant and since the water has a higher specific gravity than the oil, the water typically will collect on the bottom of the reservoir. It is a common practice in rolling mills for the operators to regularly drain gross amounts of water from the bottom of the lube oil reservoir several times a day.
This process is called decanting, and although it does get rid of a lot of water there is also a high percentage of oil that is lost during decanting which must be replenished and removed in waste oil treatment. The demulsibility of the oil is a function of the base stock quality and the oil’s ability to remain chemically stable. As the oil degrades over time and becomes contaminated, demulsibility of the oil can be greatly reduced resulting in high levels of emulsified water not easily removed by decanting. As the water level increases, there can be significant lubricant viscosity losses yielding thin oil film damage, increased oxidation, bearing damage from poor lubrication (~$30,000 each) and premature fluid replacement. These conditions are accepted in many steel mills as normal.
Using vacuum dehydration, instead of the traditional centrifuge and decanting techniques, you can address the entire dissolved, emulsified and free water problem. The vacuum dehydration oil purification system will remove water and particles, which will improve demulsibility and fluid cleanliness of the oil. Once the oil is properly conditioned, the useful life of bearings is extended as is the life of the oil (changing the Morgoil in your lube system can cost up to $150,000).
Other benefits of vacuum dehydrators include: eliminating roll-stand leakage, seeing a decrease in oil consumption, eliminating the need for decanting and minimizing the environmental impact of the mill. Protect your bearings, fluid, budget and uptime by properly conditioning your oil.