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Forget preventive maintenance. Today's uptime requirements call for an entirely different approach
MTS and National Instruments put together a joint solution that combines MTS' noise and vibration I-Deas software with NI's I/O cards and LabView software. It can sample, process, and analyze up to 5,000 channels of vibration data.
Much of what a maintenance department needs is already contained within a system's real-time database or its process historian. Temperatures, pressures, control signals, and a host of other process data can be used by software to analyze loop performance and detect problems.
You can get the rest of the data you need by installing condition-based monitoring systems on certain assets, or dig diagnostic data out of your HART and fieldbus instrumentation. If you can find it, that is.
"Last year, every major DCS player introduced HART I/O, either their own or as a reference," says Louis Szabo, vice president of Meriam Instrument (www.meriam.com). "There are HART multiplexers to bring HART diagnostic information into existing systems." The problem is, HART device descriptions (DDs) supplied to the HART Communication Foundation can't handle all the capabilities of the devices. "So vendors are coming up with different schemes. The HART Communication Foundation, Fieldbus Foundation, and Profibus International are promoting enhanced or extended device descriptions (eDDs) while Invensys and European-based vendors are supporting FDT/DTM alternatives."
In other words, the information is out there, buried inside HART and fieldbus instrumentation, and all you have to do is extract it. It's not always easy, especially in mixed legacy systems.
"I'm using Foundation fieldbus [FF] in our process plant, and I have problems with the instruments due to the architecture," laments Jorge Cano, process control engineer at MetMex Penoles, in TorreÂ³n, Coah, Mexico. "We have a Rockwell ControlLogix PLC, but all interface to FF is with National Instruments FF Configurator software." Cano is using Rosemount instrumentation and Rockwell RSView 32 software. "The results are bad. The maintenance costs are very high, process improvements are difficult to implement, and failures in our process and equipment occur many times. I have plans to migrate to Plant Web with our platform."
With all due respect to the equipment named, such problems are not rare and are not caused by the equipment. We hear from many engineers that bringing up a fieldbus system of any kind can be a bear. But there has been progress. Perhaps in a year or so there may be better software available that will let you obtain the necessary maintenance information from HART and fieldbus more easily.
Once you obtain the necessary field data, a host of software packages is available to help you interpret data, analyze conditions, predict problems, and recommend solutions. These range from CMMS packages that help schedule maintenance procedures to performance monitoring software that analyzes plant data and looks for loops that are not performing up to snuff.
RCM is such a major change from the old, easily understandable preventive maintenance techniques, it's no wonder that engineers are reporting mixed results.
"We use Emerson's AMS on control system equipment," says Joe Pittman, principal safety systems specialist at Lyondell/Equistar Chemical, Channelview Texas. "Other than an automated documentation system, I have seen little benefit on the sensor side. It has provided benefit on the valve side, with the ability to do valve scanning and define which valves need to be pulled and repaired during turnarounds."
Such systems also require a major change in attitude. "Syncrude has an AMS server from Emerson in parallel with its Honeywell TDC 3000 system," says Ian Verhappen, instrument engineer at Syncrude in Fort McMurray, Alberta. "It has not been integrated with the remainder of the maintenance software system for two reasons: first, bureaucracy; second, buy-in from the maintenance team and their supervisors, who do not understand these systems require work to get results. As with many engineering projects, the biggest hurdle is not introducing the technology, but rather the culture change required after the fact to use it effectively."
In other words, the tools to implement an RCM system are available. You just have to conquer a few minor obstacles--such as fieldbus idiosyncracies, bureaucracies, old equipment failure theories, politics, and maintenance department mindsets--to make it work.
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