- Slides: 38
Useful Predictive Maintenance Technologies for Manufacturing Facilities
• Predictive Maintenance or Pd. M is defined as efforts that are designed to detect the onset of a means of degradation with the goal of correcting the degradation prior to significant deterioration of the equipment or component. • Simplified, Pd. M is an effort to find problems and correct them before something catastrophically fails, and removes a facility, machine or production line from effective operation.
• The diagnostic capabilities of Predictive Maintenance Technologies have increased in recent years, largely due to new sensor advancements. I have been in the Predictive/Preventive maintenance business for almost 30 years. The innovation and enhancement of Pd. M/Reliability practices has truly been a continual improvement process.
• Any truly effective Pd. M effort utilizes Vibration Analysis as the cornerstone of the program. Vibration Analysis is paramount to such an effort. • However, the challenges of implementing a successful facility-wide Vibration Analysis program are numerous.
• Cost vs. perceived benefit • Lack of understanding of the technology • It is not a go/no go technology, and requires a well trained analyst to be effective • Lack of management buy-in • Lack of training if attempted in-house • Maintenance resists being proactive and remains in a comfort zone of fighting fires
• And the list continues. But let’s move beyond Vibration Analysis and discuss some of the other Pd. M technologies, and diagnostic tools that could be of immediate, if not extreme value to your facility.
The Predictive Maintenance Technologies for discussion today are: • Infrared Thermography • Ultrasonic Scans • Oil Analysis
Infrared Thermography • Infrared (IR) Thermography is the process of generating visual images that represent variations in IR radiance of the surfaces of objects. This IR radiance of the object is proportional to its existing temperature. This is accomplished with an Infrared Imager (camera).
• The principal value of this type of inspection deals with In-Plant Electrical Systems and components. Electrical problems are known to be a fire hazard and many Facility Insurance providers demand proof of IR electrical testing scans or give a discount for providing such evidence. • IR scans are successful in identifying problems with electrical, mechanical, process, roof, insulation, and sometimes moisture issues.
Infrared Thermography Case Studies • The following picture shows a fuse block with three 100 amp 600 volt fuses. • To the naked eye all seems fine.
• The Infared Thermography Scan tells a completely different story. The top clamp on the third fuse was very loose with a temperature of almost 300 degrees! Fire hazard? Failure waiting to happen? Probably both. • This is a disconnect for an industrial fan. The fan was temporarily idled, locked out and a qualified Electrician repaired the clip. Afterwards this same scan had temperature readings that were no greater than 98 degrees.
• This is a photo of a motor and pump combination in a manufacturing facility. Again to the naked eye there does not seem to be a problem. It is very doubtful that a Mechanic or an Electrician walking by on a PM would suspect a problem.
• However the IR scan shows that the motor was running at an elevated temperature of over 200 degrees. This temperature is detrimental to the insulation, the iron, the windings and the grease in the bearings. • The motor was shutdown and a redundant pump that was put into service. During the motor rebuild the motor repair shop said that the motor had been “pumped full of grease”. The added value here was that the plants lubrication program was amended to assure that this did not happen again.
Ultrasonic Inspections • Ultrasonic or ultrasounds are sound waves that have a frequency of greater than 20 k. Hz. These frequencies are not perceived by the human ear. Non-contact Ultrasonic Detectors are utilized in Pd. M to detect airborne ultrasound. Contact probes are used for diagnostics with bearings, steam traps, etc.
Ultrasonic detectors are useful in identifying problems in: • • • Compressed gas (air) leaks Compressed fluid leaks Vacuum leaks Steam trap failures Bearing condition monitoring Electrical arcing/tracking or corona testing
• Let’s focus on Compressed Air leaks, as this is the proverbial low-hanging fruit in most facilities. • Compressors that generate compressed air for a facility’s demand are inherently expensive to own and expensive to operate. They are a major source of the Electricity costs associated with operating most facilities. If there are leaks in the compressed air system, the compressor is operating, degrading, and utilizing electricity while providing no value to the facility. The leaking air is simply a source of cost to the facility, both immediately and in the future.
• I have never heard of a single compressed air leak survey that resulted in finding zero air leaks. On the contrary a typical survey will identify dozens of sources of leaks and at times that number is greater than one hundred. Some facilities are acutely aware of this and have their compressed air system surveyed several times a year. Due to the inherent cost/benefit ratio, it is my opinion that an annual survey should be a minimum.
Compressed Air Leak Case Studies • A manufacturing Plant in the southeast had two compressors at the plant site. Both compressors were continually operating. Plant management had assumed that there was then a need for a third compressor and had budgeted capital dollars to install a third unit. Before the purchase and installation of the third compressor, a Compressed Air Leak Survey was performed in the plant. This survey identified 107 air leaks that were tagged for repair.
• Subsequent to the repair of the tagged leaks the two existing compressors were capable of handling the needs of the plant with capacity to spare, and only one compressor was operating for much of the day. Calculated at $. 05/kilowatt/hour to operate the compressors, and the fact that the plant operated 24 hours a day it is estimated that the Energy savings were over $70, 000. 00 per year. That savings is in addition to the fact that they did not have to spend the capital dollars to buy, install, and operate another compressor.
• This is a real example, folks. It may be an extreme example, but true. Let’s look at an example from another senario. • Let’s assume that all the air leaks in your facility combined equate to an opening of 1/4”. That’s all of the cracked tubing, all of the loose fittings, all of the threaded connections that are leaking-by, etc. • Let’s also say for this example that the facility only operates 8 hours a day, 5 days a week.
• That 1/4” total air loss would result in $2, 000. 00 in Energy savings per year @ 8/5 operation. • If the plant is operating 24/7 the estimated savings would be $ 8, 000. 00 annually. • So, is this “Low Hanging Fruit”? No machinery to replace, no energized components to work on, no hot work permit, just some fittings, sealing, tubing replacement, etc. Rudimentary maintenance, if they know what to fix.
Oil Analysis • Oil Analysis or Tribology is one of the oldest Pd. M technologies that is still used today. It dates back to just after World War II and was first utilized by the railroad industry to monitor the health of diesel engines in locomotives. • Oil Analysis is used to determine three basic machine conditions relating to the machine’s lubrication or it’s lubrication system.
• The first condition is that of the oil. That is, will its current condition lubricate as per design? This is determined by the viscosity of the oil. • The second is the condition of the machine itself. By analyzing wear particles present in the lubricant, machine wear can be evaluated and quantified.
• The third is assessing the lubrication mechanism itself. Have the physical boundaries of the lubricant been compromised or contaminated? Water is the main culprit, but other contaminates could be intrusive depending on the operating environment.
• Oil analysis is most often an outsourced function. Oil Analysis Labs typically provide oil sample bottles and labels with mailing instructions that the plant utilizes to gather and ship the oil samples. • Oil analysis is performed on machines and components such as:
• • Oil lubricated motor/pump/fan bearings Antifriction (sleeve) bearings Oil lubricated Ball Bearings Oil Lubricated Roller Bearings Gearboxes Hydraulics Any system where the condition of the oil is directly related to decreased equipment wear, longer lubricant life, or improved equipment reliability
• Oil analysis is another potential for a good return on the investment. Oil samples are typically analyzed for $30 to $100 per sample depending on the level of analysis required. Most facilities are effectively supported with the lower end of this analysis range. • The costs are high when machinery and components fail. Equipment replacement cost, labor cost, the lead time in acquiring replacements and downtime/loss of production associated with a bearing or gearbox failure can be tremendous.
Oil Analysis Case Histories • Oil Analysis was performed on a large electric motor with antifriction or sleeve bearings. The oil analysis showed that wear particles as large as 30 microns were suspended in the oil sample. The bearings were flushed and new oil was added. • Also, a new set of bearings were acquired due to the oil sample analysis and report.
• Several weeks later the motor was scheduled for downtime. The existing bearings were rolled out. There was visible damage in the babbitt of each of the plain bearings. • The new bearings in-hand were installed and the plant averted a shutdown due to a bearing failure.
Oil Analysis Case Histories • An oil lubricated Cooling Tower gearbox was found to have a breakdown in the lubricating properties of the oil as well as being contaminated with water. • Due to the Oil Analysis report, further inspection of the gearbox was performed. This effort revealed a damaged seal that was allowing the intrusion of water.
• The seal was replaced and the gearbox was spared an untimely death as the water would have continued to invade if the oil analysis had not lead to the mechanical inspection of the gearbox.
In Conclusion • I began this discussion with “useful”. Maybe cost-effective or of-value would be better descriptions for this discussion, but the fact remains that some Predictive Maintenance applications may be difficult to quantify in regards to the return on your investment.
• Vibration Analysis, being the foundation of Equipment Reliability Based Technology is certainly useful and of extreme value if managed properly. • However, it is but one of several tools to help keep plants from unscheduled downtime as well as in capturing cost savings. And maybe the costs savings from some of the other Pd. M Technologies discussed today could help justify a Vibration Analysis Program! ?
J. Scott Glover, President The ADVANCED Team, Inc. 126 Periwinkle Lane Mooresville, NC 28117 800 -732 -2890 toll-free 704 -528 -3628 fax [email protected] ADVANCEDteam. com