Improving Predictive Maintenance through Infrared Thermography

By Roy Huff | August 27, 2007
Many quotations reflect change. "People will accept change when the fear of the present is greater than the fear of change itself," said Buck O'Neil, the first African American coach in Major League Baseball. It's time the ethanol industry changed from reactive to condition-based maintenance, and infrared thermography is a great place to start.

Thermography is becoming one of the hottest (pun intended) maintenance technologies available. An infrared camera, in the hands of a skilled thermographer, can provide huge returns for companies by increasing uptime, improving reliability of manufacturing assets and processes, reducing the risk of fire and improving personnel safety.

Production equipment and processes exhibit their own unique thermal patterns, which consist of hot and cold invisible thermal radiation, or energy, that can be viewed and imaged with an infrared camera. Infrared imaging systems allow us to "see" these thermal signatures. This is a non-contact test method and can be conducted while the equipment is in operation, thus limiting disruption to production. Real-time images can be recorded and analyzed to determine the condition of the equipment or product. Thermal information can help reduce downtime by identifying potential problems long before they become catastrophic failures.

For instance, on a recent thermographic survey, a thermographer noticed abnormal temperatures emanating from a large electrical transformer (Figure 1), which when visually inspected hadn't indicated a serious problem. The thermographer's report was given to the facility's electrical department for further investigation. Two days later the transformer was removed from service and according to the electrical department, found to be very close to a total meltdown. If the piece of equipment had catastrophically failed, it could have caused a severe disruption to the plant operations and resulted in fire and personnel safety issues.

Infrared thermography is incredibly versatile. It can be used on all accessible electrical equipment when looking for high-resistance connections and loading issues.

An often overlooked application includes mechanical equipment. Rotating assets can be inspected to identify lubrication issues, misalignment, motor wear, and failures in couplings, gearboxes, conveyors, pumps, belts, sheaves and blowers (Figure 2). Other applications include viewing storage tank liquid/sludge levels, refractory and steam traps. As equipment fails, there is often added heat or varying thermal patterns. Several thermograms or infrared images are included in this article to illustrate the versatility of this reliable tool.

Technology Supplier Options
After understanding the opportunities provided by thermal thermography, the next step is deciding who will complete the inspection work. Several variables must be examined to make a correct choice. Three options include: developing and internalizing the program, hiring an outside contractor, or developing a hybrid program utilizing both options.

With recent improvements in the infrared camera market, this technology is more affordable than ever. More facility operators are considering internalizing their infrared programs, but equipment cost is just one of the variables in the decision-making process. The facility size, manpower, applications, training budget, implementation timeline, employee know-how and management commitment should be discussed before internalizing a program.

Subcontracting continues to appeal to many operators. If the goal of the inspection is meeting insurance or company mandates, a subcontracted annual inspection will suffice and in many cases be the most economical approach. Subcontracted services also ensure the use of a qualified, trained and experienced thermographer using modern equipment. This route also offsets the expense of purchasing equipment. Make sure the subcontractor can support the development of a solid, condition-based monitoring infrared program that meets the facility's needs.

Another approach gaining popularity is having a high-end contractor develop an infrared program. This includes the selection of equipment and personnel, establishment of inspection procedures, development of inspection routes and frequencies, and the creation of baselines and databases. Site personnel attend training and receive mentoring from contractor personnel during the establishment of this style of program. The end result is a solid, well-designed infrared condition-based monitoring program, which when effectively implemented can eventually be sustained by in-house personnel. In addition, the company may wish to keep a contractor expert on retainer to perform audits or assessments of the in-house program to support its continuous improvement.

Selecting a Contractor
Should a facility operator decide to contract predictive maintenance services, several things should be required and requested from the supplier. The contractor should have someone on staff responsible for the quality of the predictive maintenance technologies offered, as well as personnel qualification. These responsibilities can be met by someone having the appropriate experience and training, or by obtaining the services of an outside agency to act as their American Society for Nondestructive Testing (ASNT) Level III certificate holder. This individual or company is responsible for developing inspection procedures, providing certification training and testing for infrared staff and participating on-site personnel, and providing overall project management for predictive maintenance programs. The contractor should provide industrial references and have general liability insurance in effect for the entire contract period.

The contractor should also provide a thermographer that fulfills the requirements needed to meet ASNT Level I or Level II certification. The thermographer is responsible for conducting the inspection, analyzing images and creating a report. Therefore, he or she must be thoroughly familiar with performing a wide range of thermographic inspections and understand the parameters needed to acquire accurate temperature measurements and how to analyze the data. Many insurance companies require that inspection work be completed by a Level II thermographer for the insured to receive any discounts or credits.

The development of "inexpensive" infrared cameras has created an influx of under-qualified thermographers. Many contractors are purchasing infrared equipment and offering services without sending technicians through training and obtaining proper experience. The most effective use of thermography-mechanical applications combines a strong mechanical background and a thorough understanding of heat transfer and the physics behind radiation. If a proposal seems too good to be true, it probably is.

Return on Investment
A few statistics may help to justify or explain the benefits of a robust reliability program. The time associated with repairs can be reduced by as much as 50 percent because they can be more accurately planned and scheduled. Maintenance, repair and operations (MRO) inventory can be decreased by as much as 50 percent. Instead, facility maintenance personnel can rely on the results of predictive maintenance technologies to order parts for repairs. In fact, one of the Big Three U.S. automakers estimates that $500 of the purchase price of every vehicle sold can be attributed to MRO inventory.

Unexpected failures and maintenance costs can also be reduced by as much as 50 percent by developing a program exercising maintenance and best reliability practices. Our clients are reporting a positive effect on their company's profits as a result of their reliability efforts.

There are a few key items to consider to best implement an infrared thermography program. Testing procedures must be developed and include acceptable alarm limits and defined safety protocol. Personnel must be trained and written practices, clearly defining required levels of certification/qualification for predictive maintenance technicians, must be established. Reporting inspection results to all departments in a facility is extremely important. This includes developing clear and concise reports identifying anomalies and providing repair recommendations after a successful repair. Correlation of the results of all applicable inspection technologies for an asset is valuable so management can make informed decisions about the timing of a repair. The results of each technology should be combined to provide an accurate picture of the facility's health.

In summary, one must identify what predictive maintenance technologies will be applied to which assets or equipment. The next step is to decide who is going to conduct these inspections: in-house personnel, contract personnel or a hybrid program. Next, apply the appropriate technologies to the right assets at the correct frequency. Integrate the results of all applicable technologies to support repair recommendations. Use this information to generate prioritized work orders that are planned and scheduled. Complete these repairs and re-qualify or validate the repairs. Use root cause techniques when appropriate to eliminate future defects, and measure the success of the reliability program using multiple metrics.

The ethanol industry continues to change rapidly. Predictive maintenance programs need to change just as quickly. Infrared thermography can provide ethanol plant operators with the tools they need to more efficiently maintain operation and reduce downtime.

Roy Huff is an electrical engineer and manager for The Snell Group, which provides infrared and motor circuit analysis training, service, mentoring and program development. Reach him at [email protected] or (816) 623-9233. More information is available at www.snellinfrared.com.

The claims and statements made in this article belong exclusively to the author(s) and do not necessarily reflect the views of Ethanol Producer Magazine or its advertisers. All questions pertaining to this article should be directed to the author(s).