by Jeff Walkup
Mother Nature can be unpredictable and unforgiving. And because she is, mining or heavy construction work sites can experience disastrous natural events that are completely out of the control of site operations such as flooding. In the event of flooding, the safety of your people should always be your number one priority. Additionally, one of the elements of returning to normal operations quickly and safely is getting your equipment back in working order.
Effects of Water Contamination
The effects of water are dramatic and need to be addressed immediately. Equipment failure due to water contamination can be catastrophic even though the effects may take time to show. Oils and greases should be kept as dry and free of contamination as possible, but massive ingression of water and dirt due to flooding can multiply these effects.
- Rust and Corrosion – when metals are exposed to water and oxygen for prolonged periods, metal oxides are formed which can flake off from the metal surface and contribute to abrasive wear in the system.
- Vaporous Cavitation – water etching on bearing surfaces and raceways is primarily caused by the generation of hydrogen sulfide and sulfuric acid from water-induced lubricant degradation with vaporous cavitation. When the vapor pressure of water is reached in the low-pressure regions of a machine (e.g., suction line of a pump or the pre-load region of a journal bearing), vapor bubbles expand. If the vapor bubbles are subsequently exposed to sudden high pressure (e.g., in a pump or the load zone of a journal bearing), the water vapor bubbles implode and simultaneously condense back to the liquid phase. These water droplets impact a small area of the machine’s surface with significant force in the form of a needle-like micro-jet, causing localized surface fatigue and erosion.
- Hydrogen Embrittlement – occurs when water invades microscopic cracks in metal surfaces. Under extreme pressure, water decomposes and releases hydrogen. This explosive force causes cracks to become wider and deeper, leading to spalling, blistering and cracking.
- Reduced Lubricating Characteristics – oil viscosity increases as pressure increases. As the viscosity of a lubricant rises significantly, it generates an oil film which separates the contact surfaces. Water, however, does not increase in viscosity as pressure increases. Instead, it will increase contact between metal surfaces and cause fatigue wear.
- Hydrolysis – water causes degradation of oil and its additives through hydrolysis, a chemical process in which a molecule of water is added to a substance. For example, ester-based lubricants can be attacked by water and turn into acids and alcohols. This process can be further accelerated by the presence of heat, acid or metal particles.
- Reduced Effectiveness of Protective Additives – water can promote oxidation in the presence of heat, oxygen and metal and lead to the formation of oxidants and free radical compounds. These reactive compounds are then neutralized by the oxidation inhibitors in the oil. The presence of water contamination in lubricants can quickly deplete the levels of oxidation inhibitors.
- Foaming in Oil – water contamination is one of the causes of foaming and air entrainment that can lead to problems like oxidation, reduced lubricating properties and cavitation as described above.
Get the Whitepaper: The Impact of Water Contamination on Lubricants
Steps for Equipment Recovery
Following are some practical, yet often overlooked, steps for equipment recovery following a flood.
- Fully or partially submerged equipment may require extensive rehabilitation (such as a major flush of all systems). Complete a mission criticality priority assessment of the equipment, assets, and components to be addressed first. Each asset and component should be documented, and conditions tracked for any possible warranty or insurance claims and to monitor conditions going forward.
- Complete a thorough examination of your current bulk oil supply storage facilities to monitor for contamination. Bulk oil samples can be sent to the lab to determine the current state. Contaminated oils should be removed, tanks flushed, and corrective actions taken to address source of entry and the damage. Ensure that new bulk oils which are arriving meet requirements as flooding may have also affected vendor bulk fuel/oils as well. New oils should never be placed in an already contaminated source.
- Monitor fuel storage tanks for water contamination which can cause the growth of algae and microbes leading to plugged filters in both delivery and in-service applications. As water is heavier than fuel, it settles to the bottom of storage tanks and becomes a breeding ground for microbial growth. Fuel sampling and analysis can determine if bacteria, fungi, mold, and other contamination has occurred due to the flooding. Review our diesel fuel troubleshooting guide containing workflows to investigate fuel issues.
- Set up a post-flood oil condition monitoring program. Take oil samples immediately following oil drain/filter replacement. Closely monitor results of oil sampling over the next few months as residual contamination and lingering effects of flood waters may begin to show.
- Follow a rigorous oil/filter change program depending on asset mission criticality. For example, consider reduced oil change intervals upfront with a return to normal frequency based on trended oil sampling.
In the event of flooding, the safety of your people is always priority number one. In this regard, safely getting your equipment up and running again is an important part of keeping your people safe. We take our role of watching over and helping to protect your equipment – and people – very seriously. Should you have any additional questions, reach out to Fluid Life and let our 40 years of industry experience assist you.