Diagnostics Increase Maintenance Productivity

Smart, networked field devices simplify maintenance, particularly for operations covering large areas.

By Gary Mintchell, Executive Director

One group of technologies that has been making life better for maintenance, and manufacturing and production in general, involves smart, connected field devices.

The microprocessor revolutions of the past 15 years coupled with improved networking ability and cheaper digital memory led to the development of sensors and instrumentation that communicate a plethora of useful information. It also means that now maintenance technicians can know the status of a device before going out across the plant grounds or facility to check it out, thus saving a trip.

What is FDT?

The FDT Group is a Belgium-based international standards organization composed of 130 companies, universities, and consultants. Its mission is to see the FDT (field device type) networking standard evolve. It develops the standard, certifies products to the standard to assure interoperability, and markets the standard.

“The standard itself solves a couple of tricky things that were in the networking side of industrial and process automation,” says Glenn Schultz, managing director of The FDT Group. “First, many device manufacturers need to integrate into the variety of systems out there. From the end-user perspective, I may want a particular best-in-class device, but I’m not able to integrate it into my PLC or DCS or asset-management system. FDT is a way for a device manufacturer to create a driver for this device. We call the driver a DTM (device type manager). The systems supplier has a similar portion that says if you want to integrate these drivers into my system or asset-management application, you must do this on your host. So now there is complete interoperability.
Any FDT-enabled device can be integrated into an FDT host system.

“The second tricky thing,” says Schultz, “evolves simply because of the sheer number of networks out there—including fieldbuses, Ethernet and wireless. FDT standard is written so it can be used on any network or any combination of networks. The networks may be freely mixed and matched in the host system and freely interoperate among them. FDT can tunnel across the networks.” There are currently more than 5,500 registered devices with a great installed base.

The FDT standard is more than 10 years old, and in that time many technology changes have occurred, especially the development of Microsoft.Net. While The FDT Group has continuously maintained its standard, a complete update was needed two years ago, which resulted in FDT2. “This is completely backwards-compatible with the old standard,” says Schultz. “If you want to upgrade the host, the DTMs from devices still work with the new host with no loss of functionality.”

FDT2 incorporates many new features, including security and speed improvements, as well as easier installation and maintenance of DTMs. It has been adopted as an international standard by ISA, IEC and GBP (China). The FDT Group certifies DTMs and watches the metrics trends on those certifications. 2012 was a record year on certifications—in terms of most manufacturers, most devices, most certificates. The entire certification question is driven by the end-user community, so the user gets a compliant product. “They like independently certified products,” says Schultz. “Many of our large end-users in their bid specs will say you must have DTMs and they must be certified.”

Maintenance benefits

Some overlap in benefits exists for maintenance, operations and engineering. The hot button for everyone beyond interoperable networks is that enhanced remote diagnostics supplied by device manufacturers—the promised holy grail of all intelligent devices—exists. Anyone can sit at a desk and look at the health of the device, dialog through the DTM to immediately access and check things out. So even before things go down, users can see the trends and potential problems, all before having to go out to physically check out a device.

Maintenance gains using diagnostics from the system can be further seen from this example from the Neste Oil refinery in Porvoo, Finland, where the company recently entered the age of proactive condition monitoring. Its Metso automation system was complemented by Neles FieldCare, a management and condition-monitoring software system for field devices that is based on open technology. Neles FieldCare is based on FDT technology in which 63 device manufacturers participate. The Web-based software enables management of devices by using either a manufacturer-specific or a generic DTM. Separate tools for each device are no longer needed. Tools are integrated in areas where this is most needed: maintenance, diagnostics, servicing and the management of process devices.

“This means that for the first time our automation department can anticipate its maintenance needs throughout the entire production line,” says automation engineer Misa Naumanen, who is in charge of the refinery’s automation maintenance. “The system provides us information that wasn’t available in traditional automation operations.” The bigger challenge, however, had less to do with technology than the need for Naumanen to sell the new way of working to his installers. Work routines that evolved over the decades had to be changed toward a more proactive approach to maintenance.

Changing the nature of work 

As the person in charge of the device and system development team in the refinery’s automation department, Jari Manninen knows that the real benefits of the new system are long-term. “Our task is to learn to use the growing amount of information,” says Manninen. “During the adoption stage, we have had to parametrize field devices more accurately than before. In the long run, however, we will reap the rewards. What we seek with FieldCare is good usability. If we can avoid even a single large ramp-down with the system, it will have brought us considerable savings.”

The company also hopes FieldCare will make it possible to reduce the number of devices and equipment that need maintenance in turnarounds. Even the location of the workstation has been carefully considered. “The terminal is next to the coffee machine. The objective is to have people use both of them equally on a daily basis,” says Naumanen.

Benefits gained from software are largely dependent on how well its use can be marketed within the work community. The FieldCare system is used on a daily basis, as condition-monitoring operations must be checked and the facility’s situation charted every morning. During the day, Naumanen will return to the application as he can. “The system is beginning to control our operations,” he says. “In the past, it used to be a case of something going wrong somewhere, and us having to go there and fix it. Now we are increasingly able to start work before problems arise.”

System Expert Tenho Eteläinen confirms that the maintenance experiences have been rewarding. “Our condition monitoring has detected deficient devices,” he says. “In the case of valves, this means that the slightest shift in a process could have caused large problems. Now we have been able to notify the production team of faulty parts or equipment and advise that we would replace them,” pointing out that in a demanding process, even the operator cannot be aware of each measurement result.

Standards assist daily maintenance

Jim Cahill, chief blogger for Emerson Process Management, a technology supplier, writes a long-running blog called Emerson Process Experts. One post on the blog by fellow Emerson Process writer Chris Womack discusses new device diagnostics standards and how they’re changing daily planned maintenance, including turnaround planning.

In an earlier post, Cahill wrote about how the Fieldbus Foundation incorporated the NAMUR end-user association’s new recommendations for device diagnostic functions and status reports, known as NE 107. The result is the Fieldbus Foundation’s FF-912 diagnostics profile specification. According to Womack, Emerson’s networking expert Jonas Berge says FF-912 is “an important part of broader changes that herald a new era in intelligent device management.”

Berge also says plants can make intelligent device-management software part of their asset-management systems, and can be a natural aspect of everyday operations for years to come. The key is to follow a simple process from audit to device-alarm rationalization, work-practice review and training. That’s because NE107 and FF-912 are propagating this alarm rationalization industry-wide.

Device diagnostics can be configured to one of the status categories in the NAMUR NE107 recommendation: Failed, Off Specification, Maintenance Required or the slightly different Function Check. This simplified status signal makes device health easy to overview and is the basis for routing device diagnostic alarms to the right person, regardless of communication protocol used by the device. NE107 also defines standard icons and colors to signal the device status in the dashboard part of the device description file. Such a dashboard can be displayed both in the intelligent device-management software as well as on the operator console.

And with some changes to work processes, “central ‘desktop maintenance’ planning can become a reality,” says Berge. The daily maintenance routine must start with checking the intelligent device-management software alarm summary for a prioritized list of devices in need of maintenance, to know which devices are in most urgent need of service that day, and to schedule the day’s work.

For instance, device self-diagnostics, such as built-in continuous valve-friction monitoring in a valve positioner, reports to the intelligent device-management software when friction is high and valve maintenance should be planned. For a plant turnaround, the planning procedure should be to check the software first, well before the turnaround, to determine which valves and which flow meters really need to be pulled out for maintenance or sent for calibration, and which ones do not. Thanks to valve-signature diagnostics in valve positioners and meter verification in flow transmitters, it is possible to tell which valves have suffered wear-and-tear and which flow meters have drifted. These tests are non-intrusive and can be done while the plant is still running.

Using this methodology, the scope of the turnaround maintenance can be reduced, freeing up resources for other turnaround tasks and also shortening the duration of the outage. The serious cases are prioritized and done first, while the rest are done if there is time left over. Savings from not wasting time and resources on valves and flow meters not in need of service include costs for cranes, hoists, scaffolding, fitters, riggers, instrument technicians, plus insulation and other material. Clearly the technology exists and is readily available to allow maintenance departments to become much more proactive, and save themselves many trips out into the plant. MT