A chemical plant installed an online monitoring system on its cogeneration plants gas turbines to analyze vibrations and warn about imbalances, wear or other dangerous conditions. Soon the monitors began to sense problems. The maintenance crew could not determine the source, even after spending an entire planned outage trying to isolate the problem.
Finally, the plant called in Richard Pratt, a regional services supervisor for Emerson Process Managements Machinery Health Business, Austin, Texas. From the start, Pratt sensed it was not really a vibration problem. I saw a 60-hertz signal on all eight proximity probes and the four accelerometers, he recalls. Those signals were everywhere, even areas where I didnt expect to see vibration.
Pratt attached his portable vibration-analysis system to the turbine to check the accuracy of the online monitors. They showed only normal readings. After that, I knew it had to be electrical, he says. He quickly traced the problem to a ground loop in the sensors.
Pratts recollection underscores why a growing number of chemical plants outsource diagnostic maintenance. Pratt or someone like him is available when they have a problem. He has the right technical training. He brings specialized tools. Most importantly, though, hes experienced. In the case of the turbine, he quickly zeroed in on the unusual 60-hertz signal.
One of the biggest problems in vibration analysis is that many companies dont have the resources to retain a full-time analyst, Pratt explains. That means somebody is doing the job in their spare time. Like any other skill, you have to have a lot of training and use it constantly to get good at it.
Experience is critical in diagnostics in general, notes Ricky Smith of reliability-improvement-specialist Ivara Corp., Burlington, Ont. You almost always have to outsource large, complex problems. You need somebody with experience, and you cant get it unless you deal with major problems all the time. You can hire smart people, but cant keep them in practice.
That ties in with a wider problem at plants. After decades of winnowing down maintenance staffs, chemical producers have fewer trained workers. As members of this aging workforce leave, their skills become harder to replace.
Diagnostics is not the most difficult thing to learn, says Emerson product marketing manager Todd Reeves, but every plant has turnover. People are promoted, recruited or they get good enough at data collection and analysis to start their own company. So you have to retrain people from scratch.
In contrast, outsourced experts have both training and experience. Most of the big, reputable firms meet all ASNT [American Society of Nondestructive Testing] certification requirements, says Jim Humphries, vice president of performance technology for Fluor Global Services, Greenville, S.C.
The ability to respond rapidly to emergencies is also important. Thats why gamma-scanner Quest TruTec, La Porte, Texas, operates seven offices in the U.S. Mostly, we respond to emergencies, says Dave Ferguson, director of tracer applications. At least 50% of the time, they want service this week. About 25% want it tomorrow and about 10% want it today.
These factors certainly have not been lost on chemical producers and are key reasons why diagnostic maintenance has long been outsourced. In the past, the work largely went to individuals or small consulting firms with narrow areas of expertise <em dash> one might monitor for vibration, while another provides eddy-current inspection.
Plants still use these small specialists. Now, however, larger firms like Emerson, Fluor and SKF are playing a bigger role.
Larger vendors typically have a lot to offer. They have the heft to sign multi-plant contracts. They conscientiously train and certify service personnel. Most can draw on deep analytical capabilities. Increasingly, they can deliver online products that monitor critical equipment in real time.
These bigger companies often provide maintenance diagnostics as part of a broader package. Emerson, for example, sees machinery health monitoring as one component of its PlantWeb services, which help companies optimize assets and implement predictive (as opposed to time-based) maintenance.
Not only can we do their outsourced condition-based operations and maintenance management, but we also rewrite their work practices to take advantage of todays advanced diagnostic technologies, notes Reeves.
At Fluor Global Services, which will earn about $1.5 billion in revenues this year, outsourced diagnostics supplement the companys broader plant maintenance and operational services, says Humphries.
We help our customers figure out the right things to monitor and whether to monitor them full-time or periodically, Humphries states. We determine the right techniques to apply and what plant services they need to outsource. We help build their business cases, train people we do it all, from soup to nuts.
SKF, a company best known for bearings rather than the rotating equipment they go into, also is actively involved. In the mid-1990s, we started going into factories to do predictive maintenance as opposed to waiting until equipment came back for repair, explains Scott Brady, director of product marketing for SKF Condition Monitoring Inc., San Diego. Like everybody else, were selling equipment and services. We do an audit, look at all the equipment and provide vibration analysis, temperature, process data inspection all the things you need to achieve operator-driven reliability.
New technologies have made the migration to outsourced diagnostics easier. Nowhere is this more apparent than in data loggers now available. Many of todays experts cut their teeth copying readings from portable instruments and re-entering them into spreadsheets to make calculations. Now, portable equipment not only captures information, but processes, graphs, analyzes and transmits it on the spot. It was almost a black art when I began, says Humphries. In some ways, it still is, but the tools provide a lot of analytical help.