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As a service provider, we often field emergency requests to clean systems that were commissioned without flushing activities or cleaning.
Facilities’ quality control programs are often trusting the manufacturer’s description of “verified clean.” However, debris, shavings and other macro and micro contaminants are usually still present. The clearances on bearing film or servo valves are minuscule. Particulate that may be invisible to the naked eye can damage these critical components. Conco is often called after a startup has been attempted due to plugged filters or a failed startup.
What causes these expensive failures? Common culprits include purge paper, ear plugs, sunflower seeds, wire ties, weld slag from new pipe installations, silica from laydown yards and transport, and unfiltered lubricant. Conco was hired to flush a new stainless steel lube oil system at a packaging plant that thought the system came with a high level of QA/QC during the pipe fitting installation. This was to be a “quick flush.” A water bottle and other contaminants would have been pushed through the system at startup had this flush not been performed. A commissioning or maintenance oil flush can prevent the damage and headache of a failed startup and protect equipment life.
Why is “verified clean” not enough? OEM’s standards are based on the minimum requirements set for hitting turbulent flow with no hard particles on the inspection media. In fluid mechanics, a Reynolds number (Re) < 2300 indicates a laminar flow regime, while Re > 4000 indicates turbulent flow. However, there is a transient flow regime between the two values and the transition to turbulent flow doesn’t occur at a specific value. Industry standard for oil flushing has determined that a Re 4000 is the minimum standard for achieving turbulent flow, but at this measurement there is not enough turbulence to pick up and carry out particulate and other foreign material. Accepting the lower flow rate may achieve the required cleanliness level but can’t guarantee that material won’t be dislodged into those components later.
Flushing activities typically occur at 2–3 times normal operating flow or at a minimum of Re 10,000. Small bore pipe and tubing may be an exception due to the pressures that accompany the flow. The flush is about maximizing the flow rate, specifically turbulent flow and should always incorporate a pathway to remove all contamination and restore the system to recommended cleanliness levels.
Cleaning the reservoirs and flushing lubrication oil systems should be included during all major turnaround and pre-commissioning activities. Lube oil reservoirs are made to dissipate heat and allow contaminants to drop out. We have seen contaminants reach levels where they cause pump damage or excessive filter usage due to neglecting reservoir cleaning and flushing activities.
In the reliability and maintenance world, we have seen a move toward utilizing solvency enhancers and improved online filtration in lieu of flushing activities. While these methods can extend the life of the lubricants, reduce bearing temperatures, reduce servo and control valve sticking, and prevent break-down between outages, they will not remove non-hydrocarbon based foreign material that can build up in the system or become introduced during maintenance activities. Therefore, unless varnish is the only contamination, solvency enhancers should not replace all flushing activities, but be used in conjunction with the flush.
Systems that have both varnish contamination and particulate may require a combined service. Varnish mitigation using ion exchange resin filters, Mobil™ System Cleaner/Step 1 detergents, Mobil™ Solvancer®/Fluitec DECON™ solvency enhancers, or in extreme cases water-based chemistry. These systems require review of how the contamination is formed to provide the best path to removing them. One size does not fit all, and many mitigation techniques fail if not applied correctly.
Avoid startup failure by implementing an oil flush
Conco can review and offer comprehensive cleaning plans for your systems. Every plan is customized based on system condition, timeline and budget and can implement cross-service methods when applicable to expedite the system cleaning. This can take place by combining:
1. Chemical cleaning and oil flushing
2. Water jetting, oil flushing and dehydrating
3. Use of a solvency enhancer pre-flush, oil flush and conversion methods
Conco’s engineers and subject matter experts design the right solution for the situation, then provide equipment, parts and experienced personnel to execute approved procedures.
Protect your investment in critical components by truly verifying cleanliness of your systems.
For more information on high velocity oil flushing and other services, email info@conco.net.
