When you have to hop on a helicopter to investigate instrument failures and make repairs, remote diagnostics becomes more than just a matter of convenience. It’s also a matter of money. Without diagnostics, your bottom line can take huge hits when equipment fails without warning and your maintenance technicians have to fly out to one of your natural gas platforms in the English Channel or North Sea.

Because reducing these expenses was important to GDF Suez A.B., the Paris-based energy company invested in digital fieldbus technology. Intelligent sensors on the network now warn the operations staff early about developing problems, so technicians can take corrective action before they have a chance to degenerate into outright failures. Even better, the inherent diagnostics can often provide technicians with enough warning to make the repairs during a scheduled stop to the platform.

GDF Suez opened this window into its operations when it upgraded its old network of pneumatic controls and discrete wiring to a new one based on Foundation Fieldbus from Phoenix-based Honeywell Process Solutions. “The Foundation Fieldbus system integrates with Honeywell transmitters, as well as other, third-party transmitters,” says Hans Katers, GDF’s head of mining installation.

The resulting digital network established serial, two-way communications with the company’s offshore platforms, thereby allowing both remote control and monitoring. Now, the operations staff has access to more information that can tell it whether feedback devices are operating correctly and whether the process information that they are transmitting is good or bad. Not only are technicians spending less time verifying whether the devices are working, but they no longer need to perform many of the routine checks that they did before.

The ability to track trends also gives them prognostics. “The ability to predict [performance] also helps increase platform uptime and performance by detecting or predicting deteriorating performance and failure conditions before they cause any problems,” notes Hans Kwee, one of GDF’s instrumentation engineers.

This combination of diagnostics for assessing the health of an asset and the prognostics for maintaining it proactively constitute the true benefit of fieldbuses and intelligent transmitters, according to John Yingst, Honeywell’s product manager for asset management. “The value of fieldbuses is not in the wiring savings and other promises that were touted early on in their life cycle,” he says.

Easing the burden

Another advantage of fieldbus-based diagnostics is that it can supplement the Ethernet-based embedded signal processing that many in the oil-and-gas industry are putting into their machinery that requires high-speed data acquisition and feedback. Although an intelligent sensor might be adequate for some control loops in the process industry, an additional level of data acquisition and signal processing is often necessary for compressors, pumps and other high-speed, heavy machinery that are driving those processes.

“You can imagine how fast streaming raw data back to the control room would fill up the hard drives,” says Preston Johnson, segment manager for sound and vibration sales and marketing at National Instruments Corp. (NI) an Austin, Texas, automation supplier. “Processing that information to reduce it to a smaller set of much more meaningful information makes the application a lot easier.” His company does this with the latest analog-to-digital converters, field-programmable gate arrays, and microprocessors that can perform fast Fourier transform analyses on the data.

Because of the processing speed, Supreme Electrical Services Inc., a Houston-based supplier of controls and instrumentation for the oil patch, has been using NI’s CompactRIO Ethernet-based products in its high-pressure fracturing pumps. “Other hardware we considered was not able to provide the high-speed I/O (input/output) and analysis to catch the momentary pressure spikes and vibration indications of these oil-well service pumps,” says Robert Stewart, senior vice president at Supreme Electrical.

Both the high-power diesel engine and the transmission on these triplex or quintaplex pumps have an electronic interface that monitors discharge pressure, rotational speed and other operating parameters. The interface provides diagnostics while the pump is running and transmits the data to the main control console via the SAE J1939 controller area network (CAN) communications protocol. “With this real-time information, operators can determine whether they should continue or discontinue operations based on real performance indications from the pump,” says Stewart. For more on Fieldbus Technology, see "Fewer Fieldbus Programming Headaches" .

Perhaps the biggest challenge confronting companies such as Supreme Electric for integrating diagnostics into their machinery is not so much collecting data in real-time, but rather developing the software for interpreting their significance. “A facility can use OPC (an open connectivity standard) to bring together process data from ...