Asset management is the most difficult thing many companies do—far more difficult than actually making the products their processes are set up to make. The reason, of course, is that asset management for predictive and preventive maintenance is an add-on function in most plants. When these plants were built, there were enough people available to walk around inspecting assets for potential problems, and forty years ago the cost of simply replacing all the critical valves or motors every time there was a shutdown was relatively small, and shutdowns were relatively frequent.
But that is no longer the case. Staff reductions have limited the number of people able to walk around the plants. Running the plant at over 100% of capacity and lengthening the times between planned shutdowns has made preventive repair or replacement of assets, such as valves and motors, problematic and expensive. And with longer times between shutdowns, unplanned shutdowns due to deferred maintenance have become both more frequent and more expensive.
"We bought the very first version of AMS 1.0 from Emerson in 1999," says Gàbor Bereznai, head of the automation and electrical department for MOL, the Hungarian refining corporation, whose Danube Refinery was the 2012 HART Plant of the Year. "We have AMS, PRM from Yokogawa and Honeywell's asset management software as well."
Bereznai says that the Danube refinery site has 40,000 instruments, 30,000 of which are HART devices. In addition, the refinery has somewhere between 3000 and 4000 HART valve positioners.
First, MOL connected all its HART devices through hardwired HART multiplexers to its various DCSs. Then the plant began to transition toward predictive maintenance and away from replacing all the valves when a shutdown occurred.
"You can see what has happened since we standardized on HART and Foundation fieldbus transmitters and began to enable HART valve positioners," Bereznai says. "We gather information before the turnaround using the HART diagnostic data and by doing this, we save between $20,000 and $70,000 per turnaround. So we are more predictive and proactive and less reactive." (Figure 1)
Bereznai continues, "If you look at Figure 2, you can see the breakdown of costed activities relating to valves. The costs are significantly higher without diagnostics than with HART diagnostics."
He adds, "We're replacing our analog positioners with HART, and we're experimenting with WirelessHART. We're in the early stages of using Emerson Process Management's THUM WirelessHART adapters to get diagnostic information out of HART devices without wiring them to multiplexers. We have 20 units in a test application."
He says his team also worried about EMI and other types of interference. So they conducted some nearly destructive testing. With the instrument live and broadcasting, they arc welded directly to the instrument housing, and found no detectable interference from the welding.
See Also: HART to the future!