If moisture is >300ppm, BAD things are happening in Your lube system.
If you worry about moisture levels in lubrication oil, your concerns are valid. Water contamination, even in small amounts, harms your plant and machinery. Moisture shortens both the machinery’s service life and the lubrication oil’s effectiveness.
Left Unchecked, Moisture Will Affect Your System.
The Dangers of Unchecked Moisture
Catastrophic Failure
Compressors handling ‘sour’ natural gas with high hydrogen sulfide levels face serious issues when moisture is present. The interaction between oil and moisture can cause sulfide stress cracking, a type of hydrogen embrittlement. In extreme cases, this may split compressor casings.
Hydrogen embrittlement also affects other equipment. Electrolysis or corrosion releases hydrogen atoms from water molecules, creating a damaging cycle.
Corrosion
Rust impairs bearing surfaces and prevents the formation of the critical elastohydrodynamic (EHD) film needed for effective lubrication.
Impaired Film Strength
Similar to corrosion, the oil is denied the opportunity to lubricate and separate the surfaces. This occurs when dissolved water affects the viscosity of the oil and allows the load zone to force the lubricant aside and ‘bump’.
Did You Know?
Water in the bearing load zone can create superheated steam, leading to mini-explosions within the oil. This phenomenon damages the oil and can harden, fatigue, or crack bearing surfaces.
Foaming
Water, especially chemically treated water, hinders the lube oil’s ability to dissipate foam. Excessive foaming causes sluggish hydraulic control systems and can lead to cavitation in pumps and bearings.
Lube Oil Additive Depletion
Additives are designed to be a sacrificial product. They are consumed as the additive pack anti-oxidant neutralises unwanted chemical contaminants. However, if additives such as demulsifiers (which help shed water) are exposed to large amounts of water contamination, the demulsifiers can be stripped from the oil very quickly leaving the oil at risk.
Other additives like Extreme Pressure (EP) and Anti-wear (AW) can be hydrolyzed (broken down into acids) by water and deny your Equipment the protection those additives are designed for. If left unchecked the by-product is sludge and varnish.
Sludge Formation
Water’s polar nature attracts contaminants, leading to sludge formation. Sludge can overwhelm strainers and filtration systems, restricting oil flow.
Microbial Contamination
Moisture promotes microbial growth in lubrication oil and diesel. This biomass can plug lube circuits and filtration systems. Microbial contamination poses corrosive effects and health risks.
Dry Oil Equals Extended Life of Oil & Machinery
A trial of machines by the BHRA compared equipment life to moisture contamination. They found the correlation between dry oil and oil with high moisture content. Oil with a moisture level of 5,000 ppm was dehydrated and trialled to measure equipment life. The results show that equipment with oil drier than 100ppm has three times the life of a machine with oil of 450ppm moisture.
Resolving the Problem of Moisture
Many solutions exist to mitigate moisture and particulate contamination. BioKem offers various units, including vacuum dehydrator VDOPS units. These units effectively remove dissolved, free, and emulsified water and particulates from different oil types. They feature microglass filtration media that can remove particles as small as 2 μm.
If you need advice on specifying or sizing a suitable unit for your plant, feel free to reach out.
Conclusion
Keeping lube oil moisture levels below 300 ppm is crucial for increasing equipment life and prolonging oil effectiveness. Proactive moisture management leads to significant cost savings and improved operational efficiency.
If you would like further information on this article or others, please feel free to contact us.
Reference
- Sulphide Stress Cracking – http://en.wikipedia.org/wiki/Sulfide_stress_cracking
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Vacuum Dehydration Oil Purification Systems (VDOPS) – https://www.oilfiltrationsystems.com/vacuum-dehydration-oil-purification-systems-vdops