Reliability issues: Focus on reducing lubrication failures
Joe TerrettGeneral Machinery and Equipment Maintenance Manufacturing condition monitoring lubrication maintenance manufacturing reliability STLE
Highlights from a STLE Toronto workshop help with lube management.
Tribological losses that lead to damaged equipment, energy loss, and premature disposal of components, equipment, machinery and lubricants leach away the value of assets, leading to downtime and added costs. What’s needed is a little planning and to follow proper maintenance procedures.
The not-for-profit Toronto Section of the Society of Tribologists and Lubrication Engineers (STLE) offered some assistance in this regard with a workshop and panel discussion.
Held at the nuclear Ontario Power Generation (OPG) facility in Pickering, Ont., the session covered how to reduce equipment failures due to lubrication problems, waste, improper maintenance and disposal issues. How should maintenance pros maximize productivity and component life? The following highlights gleaned from the workshop offer some direction.
Cleanliness. Don’t assume new oil is clean enough. As a rule of thumb, oil should have a cleanliness level that protects the tightest machine clearance on the equipment. Terry Pitcher, indirect business consultant for Chevron Canada Ltd. who is based on Guelph, Ont., observed oil cleanliness requirements are often based on a component’s sensitivity to contamination. That’s because 82% of wear is induced by particles.
It’s often assumed new oil meets the performance and cleanliness requirements set by the equipment manufacturer. But Pritcher warned new oil could contain up to 32 times more contaminant particles than what’s acceptable. The reason? New oil can be transferred multiple times before it reaches the equipment. Oil picks up more contaminants each time it’s transferred. Filters will remove some of them, but not before they’ve caused damaging wear. Some companies choose to pre-filter new oil onsite to ensure it’s clean enough.
Additives. Gavin Duckworth, vice-president of national accounts for Functional Products, an additive supplier in Macedonia, Ohio, said identifying viscosity index (VI) improvers in today’s modern formulations, combining polymer chemistries to reduce costs and improve performance, and detecting sources of haze are possible solutions to lubrication issues.
The higher the VI, the lower the change in viscosity with temperature, and the wider the operating temperature window for equipment.
He identified advantages of polymer viscosity modifiers over blending oils: cheaper high VI (Gr. I and naphthenic with VI 140+); higher viscosity grades (Gr. III, synthetic ester); better low temperature (polymer + light oil vs. heavy oil + light oil); and low viscosity, high VI formulations are possible (low viscosity base oils tend to be lower VI).
Oil analysis. Andrew Sit, a components engineer at OPG’s Pickering nuclear facility, recommended oil analysis to detect early signs of contamination and degradation. At OPG, maintenance and operations conduct routine testing on site, at a maintenance and oil testing facility or at an offsite lab.
The crew testing the sample report any abnormalities. Test data is verified and recorded into a database that automatically generates notifications of out-of-spec conditions. Results are received and troubleshooting is conducted by the station lube engineer, systems engineer and chemistry technical section.
Filtration. Wendy Walker, general sales manager of Pall Canada Ltd., a provider of filtration, purification and separation products in Mississauga, Ont., said effective filtration is a critical aspect of any reliability program. Fluid cleanliness can be controlled to allow components and systems to operate at peak efficiencies.
Her presentation offered some need-to-know fundamentals.
Fibre size and density govern a filter’s pore size and porosity. Benefits of smaller diameter filters include higher dirt capacity, lower pressure drop and longer service life. Inert organic fibres offer wide chemical compatibility; there’s no swelling; and there are no limitations to shelf life.
Fixed pore fibres are bonded with specially formulated resin to resist deterioration from pressure, flow fluctuations temperature and age.
Non-fixed pore are inconsistently or poorly bonded. This allows movement of the fibres under pressure and flow surges, resulting in channelling, unloading and media migration.
She also compared a uniform and tapered pore construction. Tapered has a coarser upstream surface to capture larger particles. This allows finer downstream pores to capture critical clearance-sized particles. More particles captured means longer service life. Uniform pore design limits the use of effective void volume to capture particles. It increases costs by reducing the number of particles captured, and reduces filter life.
Ultrasound technology. Robert Dent, the national sales and service manager of SDT Ultrasound Solutions in Cobourg, Ont., extolled the benefits of ultrasound as an extremely versatile condition monitoring technology that is applied to lubrication, leak detection, and steam system inspection. Applying the right amount of grease, at the right location and at the right time interval is crucial. Ultrasound provides the data to optimize lubrication programs and facilitates a shift from calendar-based to condition-based scheduling.
Compressed air is one of the top three most expensive utilities used in manufacturing. Air leaks are often ignored and they’re costly. Dent’s presentation noted cost of ownership is split at 15% capital, 15% maintenance and repair and 70% electricity.
With no compressed air leak program, 40% of the electricity cost is wasted on leaks and wrong applications such as using compressed air when there is a lower cost energy source available; blow offs without energy efficient nozzles; and filters that aren’t clean.
The high frequency component of a leak is directional, making locating its source with ultrasound fast and easy. A compressed air survey once every three months will improve efficiency and reduce costs.
Ultrasound surveys of an entire steam system will reveal system leaks, blockages, stuck valves and failed traps. Dent said increasing steam efficiency means huge dollar savings and increased product quality.
Monitoring devices. Chris Henn, a territory account manager for Omron Automation Canada in Toronto, spoke about predictive maintenance for motors by applying current analysis, vibration and temperature control, and employing insulation resistance monitoring devices. He said motor monitoring devices bring practical Internet of Things to the component level. Knowing an asset’s current status and when a replacement is needed prevents reactive downtime.
This synopsis was provided by Steve Gahbauer, an engineer, a Toronto-based business writer and a regular contributing editor. He passed away in May. This is his final article.