Ultrasound: Aural Intelligence
Rick Carter | August 6, 2015
A recent three-day conference that connected ultrasound experts with maintenance professionals delivered some key points about this predictive technology.
The ranks of those who use ultrasound for predictive-maintenance purposes are growing. The trend is evident on factory floors and at conferences devoted to the technology, such as UE Systems’ (uesystems.com) recent 11th annual Ultrasound World/Reliable Asset World event. Held in June 2015, in Clearwater Beach, FL, a record number of attendees was treated to presentations that blended detailed information about ultrasound usage with practical perspectives on how ultrasound fits with efforts to build and maintain reliability-based cultures.
Two standout presentations—“Using Ultrasound for Effective Slow-Speed Bearing Monitoring” by Ron Tangen, maintenance engineering specialist, Dakota Gasification Co., Beulah, ND; and “Utilizing Ultrasound as a Foundational Technology When Embarking on a Reliability Transformation” by Mike Casey, reliability engineer, Mueller Co., Chattanooga, TN—were excellent examples of the experienced-based information Ultrasound World promised and provided.
Ultrasound for slow-speed applications
Ron Tangen’s presentation focused on how his efforts to predict bearing failures at Dakota Gasification Co.—owner and operator of the Great Plains Synfuels Plant in Beulah, the only commercial-scale facility in the U.S. that manufactures natural gas from coal—led him to ultrasound for slow-speed applications. Though his team now uses ultrasound for many applications in the plant, before its widespread use, ongoing failure issues with the plant’s many slow-speed bearings on coal-handling conveyors had been a problem.
“Operators would walk around on a weekly basis and listen and look at these bearings,” said Tangen. “If they felt there was a problem they would also touch them and maybe use a hand-held, infrared pyrometer to check temperature. But this predictive-maintenance strategy is at the bottom of the PF curve [a designator of the interval between “P—potential failure” and “F—failure”]. And, while they did find problems and got some bearings out of the system before they catastrophically failed, being so close to the end of the PF curve, they would often get done with a route and a few days later have a catastrophic failure.”
Tangen discussed the issue with the plant’s rotating-equipment engineers. “They have a robust vibration program,” he said, which worked well on high-speed bearings, but not on slow-speed. With infrared nearly as ineffective, Tangen turned to ultrasound and tested his idea. When the results proved positive, he established routes that took ultrasound-equipped operations team members to the conveyors’ many slow-speed bearings—bearings whose problems had been previously undetectable prior to failure with infrared or vibration due to their slow speeds. “Now that we’ve been doing this for five years, and after listening to a few thousand bearings,” he said, “you start to see the patterns.”
The results of routine ultrasound testing include hard-to-refute sound files of bearing disintegration. “I first thought I could give a two-week or two-month heads-up on catastrophic failures,” said Tangen, “but the ultrasound technology is sensitive enough that you can track a bearing fault through its lifetime.” By plotting the decibel readings for each given bearing and, as they accumulate, drawing a straight line through the points, he can “normalize” the data to provide an overall direction for the readings. “This enables me to project where I can potentially expect that bearing to be over time,” he said. “Right now I’m beginning to look at bearings we’ll need to pull in 2016.”
Tangen has reluctantly accepted that he’s viewed by some colleagues as having crystal-ball talents. “If you tell a lot of people that you’re predicting slow-speed bearing failures a year in advance, they might think you’re a little crazy,” he said. But they clearly like his information. In a recent meeting with operations and maintenance leaders, Tangen said “the only thing they wanted more of was my predictive report.” They asked if his standard 12-month view of predicted bearing failures could be shortened to quarterly to allow for better planning. “I’m not quite at that point yet,” said Tangen, “but I thought it was a positive note that they have seen enough value in the program to where they want more data more often.”
Ultrasound and reliability
For presenter Mike Casey, who came to Mueller Co. in 2012 from Allied Reliability Group, Charleston, SC, ultrasound was a key part of his task to establish a reliability-based culture at his new company, a maker of water-distribution products. “It was difficult knowing where to start,” he said. “When I got here we had an ultrasound gun that was used, maybe not correctly, and it needed to be upgraded. So I had two elements to work with: I had to get the funds for an upgraded model and I needed to have the people ready to use it and want to use it. I had to have more than a work order that said ‘listen.’ I needed them to go find things.”
His plan involved getting multiple members of his maintenance crew trained to use the company’s existing ultrasound gun. “Any win we could get with that would be beneficial in my request for a new unit,” he said.
Casey built on an earlier approach undertaken at the plant that had used an outside service to identify and tag compressed-air-system leaks. He trained his team to detect those types of leaks, and distinguish them from other sounds in the plant, particularly those of intentional “leaks” where compressed air is used to blow off or move material.
“I felt comfortable training them,” said Casey, who is also a Level 3 vibration analyst, “but it’s worth every penny to send that person to the OEM [for training]. It also depends on finding the right person. You can put an ultrasound gun in anyone’s hands and they can use it, but you really need that person who is interested and wants to do it. This is not necessarily the most senior guy,” he added. “The process can be grueling. It’s hot, walking, climbing. You need someone who is willing to do all of that. I would caution against randomly picking somebody and hoping for the best. You have to roll it out correctly and get the training. There will be missed calls—these aren’t crystal balls—but if you can minimize those, the technology and the program has a chance.”
It also helps that ultrasound (like infrared) comes with a powerful sensory impact. While vibration plots can “make some people’s eyes glaze over,” said Casey, “if I can show someone a colored picture that shows a temperature differential or have them listen to a sound file and actually take them to the equipment and have them put on the headphones and listen to this and demonstrate what’s going on, that’s where these technologies allow for faster buy-in. It’s more tangible, and I can make the point a lot quicker.”
Casey’s efforts to convince his management of the need to upgrade its ultrasound equipment were successful and not as difficult to achieve as he had expected them to be. “I did go with my guns loaded—I had those findings in my back pocket—but I probably could have sold it without them because the company knew they had to spend some money to get a program going. Like most companies, though, I think they didn’t know how much they had to spend or what they had to do. There was a corporate openness to getting these tools in the house, but you had to maybe put someone like me in there to make it work.”
Casey offered other suggestions for those looking to start or expand an ultrasound program. “Don’t be afraid to experiment,” he said. “Get the training and let that person go. That’s how I found some of the unique applications I did, just going out there and asking, ‘What is this supposed to sound like?’ It’s about identifying issues. The whole idea behind ultrasound is to identify problems ahead of time and come up with ways to eliminate them forever. You need to capture that data, learn how that failure was caused, and eliminate it.”
Casey’s ultrasound program has improved his company’s uptime and maintenance success. “But we still have to make product, which still produces emergency work, so it’s a juggling act,” he said. “That’s why these programs take time to mature. But when management sticks by them, and they give it time, we get our wins and we brag about them. And that’s another important piece of programs like this. You have to brag. You have to advertise those gains. You have to let them know.”
The 2016 UE Systems Ultrasound World/Reliable Asset World event is scheduled for May 10 to 13 in Clearwater Beach, FL.
If ultrasound is new to you, visit the Resource section of the UE Systems Inc. website at uesystems.com to learn the basics. Pay particular attention to the Sound Recording Library in which you can hear the sounds made by various devices in good and/or failing condition.
Ultrasound: A Multi-Use Industrial Technology
Ultrasound—literally “beyond sound”—refers to acoustic (sound) energy in the form of waves with frequencies above 20,000 Hz, the highest frequency to which the human ear can respond. In addition to its use for predictive-maintenance purposes, ultrasound has many other industrial uses, especially in processing applications. These include:
• Cleaning of equipment and process material
• De-scaling of plant equipment, evaporators, or pipework
• High-shear mixing
• Liquid/solid separation and dispersion
• Particle de-agglomeration
• Spraying/spray drying/atomization
• Waste/sludge effluent treatment