Equipment condition is monitored conventionally to avoid downtime, reduce repair costs and minimize consequential damages, but what happens when you shift the emphasis from reliability to productivity? Instead of predicting and planning maintenance work, condition-monitoring principles and technologies can inform operators directly, so they can make machine, process or operation adjustments, continue to run and maintain quality levels.
The key is to automate data analysis and render condition information in the form of notifications or instructions operators can act on in real time — to the extent possible, taking maintenance out of the loop and closing it directly between the machine and the operator.
“By managing our equipment below the alert level, we are able to be proactive,” says Jayesh Patel, reliability engineer at Valero’s Paulsboro, N.J., refinery. “This allows us to move away from reactive work and its associated process interuptions. The results of this shift to proactive are improved product quality, improved machinery availability and increased profits.”
Use today’s technology to mimic the way a human would perform diagnostics. “We’re headed in that direction,” says Don Rainey, director, Azima DLI. “The whole condition-monitoring industry will be.”
Banish squiggly lines
How equipment is operated has a profound effect on reliability. “We know 40% to 50% of breakdowns are caused by operating practices, pushing the limits to make product,” says Dan Nower, P.E., global manager, online systems, Emerson. One reason operators lean on the plant is they don’t understand the consequences because they don’t speak the same language as maintenance and reliability experts. “Squiggly lines — spectra and waveforms — make their eyes glaze over,” says Nower, “So use the DCS; that’s the operator’s language.”
So, how do we take tried and true methods such as vibration and temperature and make them relevant to the operator so they can use them and normal instrument guys can support them?
“We have to integrate the system and route the information, and that’s where changes are happening,” says Tom Alford, product manager, integrated condition monitoring, Rockwell Automation. “For example, our RS Logix 5000, which manages controller configuration and I/O, now has an add-on profile for condition-monitoring modules.”
That information can be used to drive diagnostics. For example, high vibration levels indicate a problem, and the frequency ranges can be correlated to specific faults. “Put those in the controller table, and now control logic can be used,” says Alford. “Real-time diagnostics use if-then statements to identify specific faults — for example, if vibration is high and Band 1 is high, that means imbalance.”
Smart systems can help fill the need for knowledgeable people. “With the attrition we’re seeing to the skilled workforce, we’re going to need this,” says Gina Hutto, manager, business development, services group, Timken. “Operators are the first line. We’re doing this, for example, on rollers in steel mills. We’re monitoring continuously where we used to have technicians performing rounds, and the system feeds directly into the control rooms, on the operator’s screen.”
A process control system can monitor any of thousands of variables for both prediction and protection. It can monitor machine health and know its exact condition, and it also can protect high-value assets by shutting them down automatically to prevent damage.
“In the past, it was hard to do, so people didn’t do it,” says Nower. “Now, in minutes, we can pull variables into the controls so we’re speaking the operators’ language on their system – a green, yellow or red light.”
Deliver actionable information
Operators also can make use of condition information they collect using simplified devices to measure variables such as overall vibration and temperature. “Operators are getting out there, doing rounds, collecting data with PDAs and getting it into the system,” says Scott Brady, senior manager, operator-driven reliability, SKF. “They can collect data every day, whereas maintenance crews usually only take machine readings every two to six weeks, and sometimes machinery changes more quickly than that.”
The key is electronic data entry. Once the data is on the system, it can be analyzed and acted upon. “In applications involving rounds, a lot of the data — 40% to 80% — is often paper-based,” says Chris Stearns, product manager, reliability solutions, Honeywell. This can be automated. “For example, our Field Advisor lets you identify structured rounds, get the information into our Experion system historian, onto operations desktops and into logs,” says Stearns. “Collect, synchronize and get it into databases.”
Wireless infrastructure enables other applications. “It’s good to have the infrastructure. Then wireless equipment health monitoring (EHM) is cost-effective,” says Stearns. Data comes back into the asset manager application and is presented as health indicators on the control system or in a thin-client application.
OK, you’ve turned a squiggly line into a colored indicator; now what do you do with it? If you can, you tell operators what action to take. They then can alleviate the condition or get the right people involved before the asset fails and consequential damages occur.