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Getting Back on Track with Oil Analysis

July 1, 2020
Many manufacturers were not analyzing machine oil and lubricated components during the COVID-19 shutdown. A careful consideration of these factors will promote reliable and safe recommissioning.

Maintaining the oil in industrial equipment is the simplest and most cost-effective way to promote continuous uptime and long service life for manufacturing machinery. Any manufacturer that has, until recently, been testing fluids regularly will have an advantage when preparing to resume operation after a shut-down.

However, even if the operators have been diligently caring for equipment, once it’s been idled or powered down for an extended period of time there are some considerations for returning that machinery to full production.

Many organizations were not prepared for the dramatic effect that COVID-19 would have on the global business climate. Even those operations that took action early were caught off-guard by the length and duration of the shutdown. And many business had no plan in place for the wholesale and relatively sudden decommissioning of equipment. Given all this, it is understandable that many businesses also have no a plan for recommissioning their manufacturing systems.  That’s what this article is about.

Variables that affect equipment restart — As preparations are underway to restart operations, there are many variables that affect the current condition of idled equipment.

1. Type of equipment.  If some equipment, for example rotating machinery, sits idle in one position for an unusually long period of time several issues can develop (e.g., noise and vibration) may be apparent at start-up. False brinelling of bearings can occur in the areas that experience vibration and shafts can bow if they are left in one position for an extended period.

2. Proper/improper shutdown. At the outset of the COVID-19 pandemic, many manufacturers' equipment was not shut down properly, which is entirely understandable. Many operations were not prepared for the severity and length of the situation as it unfolded, ad if they were they may have had various other details to contend with, such as caring for employees and paying bills. Proper machinery shutdown just was not a top priority in March and April 2020.

3. Condition of equipment before shutdown.  The age and the number of operating hours on a piece of machinery will influence how well it may have fared during its inactivity. If it was placed in service fairly recently, it should bounce back with few issues (the OEM will be an excellent source of recommissioning advice.)

On the other hand, if a machine is out-of-warranty or close to end-of-life, now may be a good time to think about replacing it, or at least securing a backup machine—depending on how critical the machine is to the overall operation.

4. Operating environment.  Further complicating the situation, in most parts of the U.S. the onset of the COVID-19 shutdown occurred together with a period of seasonal change. As facilities shut down, most of them will have either increased or decreased the interior plant temperature to save energy costs. Once the plants reopened, they reverted back to normal operating temperatures. Temperature fluctuations and associated condensation may affect the state of machinery when it is restarted.

In one example, a TestOil customer had machines installed in a basement where temperatures were frequently very high during normal working conditions, in the range of 110-120° F. When the plant had been idle for only a week, the temperature in that space dropped to 70° F,  degrees. Then, during the extended shutdown the temperature slipped down to 50° F. That temperature variable may make a difference in the machines' performance, especially as it affects oil viscosity upon cold start-up.

5. Length of shutdown. On one hand, a cold start is a cold start, but restarting a machine that has been idle for several months (as in the current situation) can mean unexpected results. The longer that a machine sits idle, the more susceptible it is to contamination, corrosion, the ingress/egress of fluids, and in extreme cases to insect and rodent damage.  This is particularly true for equipment that operates or has been stored outdoors. The bottom line is that failing to follow the required inspections and testing processes prior to restarting equipment may imperil the machine condition and create a hazard for workers.

Logistics of restarting — To some manufacturers it will be tempting to "flip the switch" and return to standard operating procedures, but some careful attention to details will help to promote a successful restart. A good first step will be a visual inspection to check for rust, leaking gaskets, seals, cracks, proper oil levels, and oil color.  If the manufacturer took care to prepare the equipment prior to idling it, those steps should be reversed now. If no steps were taken to control moisture contamination, the equipment should be inspected for rust and corrosion.

Surfaces will be dry and should be lubricated thoroughly prior to start up. If there is water contamination, the system should be flushed if possible. Inspect the equipment first — especially any hydraulic and lubrication systems — and drain away any water, saving a representative sample of the oil to test it for degradation. Note that, ideally, a representative oil sample should be collected as it is moving through the machine.

Recommended tests include Karl Fischer (for water), acid number, and additive levels. In most cases, the operators will not need to change the oil completely before restarting a machine.

For motors, the most frequent causes of failures at startup are bearing-related, including worn bearings, bear housings, or shafts. You cannot expect to hit ‘go’ and put a motor into service right away after a shutdown of any length. First, start the motor to see if it is operating properly.  Many problems can be detected by test-running the equipment and performing vibration analysis and/or ultrasound and infrared thermography.

There are warning signs that will indicate if the equipment needs to be shut down again, including unusual noise and/or vibration, and these should be evident right away.

Once you notice vibration or noise it's possible that the damage has already been done, so shut down the machine again, right away.

If the machine has been thoroughly inspected and evaluated, started in isolation, and operates well, you may be confident that it will perform well once it’s returned to full-production again. 

Oil analysis just after restart — Detailed oil analysis is critical to managing machine reliability, and sometimes it is complemented with technologies like vibration analysis, ultrasound, and thermography, to maximize equipment life.

While the oil can be tested prior to re-start if there are obvious issues, it’s usually better to pull a sample when the equipment is operating. For idled equipment, the first analysis should be conducted as soon as possible after the restart.

Before sending a sample to the lab, be sure that the lab understands that the equipment has been idled and for how long. At TestOil, we receive samples without background information, and customers don’t always let us know if the equipment has been down for a while.

For those plants that have been taking advantage of trending oil analysis, once the lab analyzes the first post-shutdown sample it should be possible to determine where to restart trending analysis. If that sample is more or less where the trending left off, the plant may continue trending without missing a beat.  Otherwise the oil may have to be replaced and the trending analysis reset. 

Trending analysis usually will not be a problem, as long as the operators have not changed the oil. But, if the oil has been changed the analysts must be made aware of this, and the machine operators should try to get back on schedule ASAP, sending the sample for testing a.s.a.p.

During the COVID-19 shutdown, many businesses were not analyzing turbine oil.  Getting back on track with an annual turbine analysis (ATA) is one of the keys to avoiding extensive repairs of that type of valuable equipment. An ATA will provide a window into the health of the turbine and the lubricated components.

Although most organizations are pressed for time and eager to return their operations to full production, a careful consideration of these factors will promote reliable and safe recommissioning.

Frank Rex and Matt McMahon are data analysts with TestOil, which offers oil analysis for machine condition evaluation and preventive maintenance, as well as related services and training programs. Learn more at www.testoil.com