Downtime is without a doubt the least productive time in the lifecycle of an asset. When you're down, you're not making product. And when you're not making product, you're not making money. It's no wonder that for production managers worldwide, unplanned downtime is enemy number one—followed by scheduled downtime, which they'd like to see as short as possible (and would eliminate if they could). Next to eliminate would be process variability, which typically contributes to sub-optimal operation and off-spec production.
Despite the best of intentions and much hand-wringing, the process industries continue to struggle with poor availability, boosting total production costs by as much as 10% annually. Indeed, ARC Advisory Group estimates the average cost for plant downtime at $12,500 per hour; at some plants, of course, it's much higher. Research also indicates that those scheduled maintenance turnarounds may be longer than they need to be; a full 50% of all maintenance work may be unnecessary and 10% is actually harmful, according to the Gartner Group.
To begin to move the needle on asset utilization in a positive direction, plants need a combination of better process reliability, visibility, control and understanding. Across all of these dimensions, measurement instrumentation plays an outsized role. First, the correct choice of properly applied instrumentation can be a direct contributor to overall process efficiency and reliability. Second, instrumentation can help identify and diagnose a growing number of process conditions that, if left unaddressed, could escalate to a production outage. Third, wireless technology allows the cost-effective addition of new measurement points that can help fine-tune performance, as well as liberate stranded diagnostic information needed for a more complete picture of equipment health. Finally, the integration and presentation of diagnostic information in ways that can be quickly and intuitively understood—and acted upon—can help speed turnaround time, in no small part by helping to determine what maintenance activities need not be done at all.
Reliable Measurements Come First
At the North Star BlueScope Steel mini-mill in Delta, Ohio, challenging environmental conditions including high ambient temperatures, high vibration levels and red-hot chunks of slag took their toll on the plant's traditionally wired instruments, knocking out as many as a dozen temperature measurement points each week. As a result, each of the plant's several furnaces was out of commission at least once a week—with downtime ticking away at $500 per minute.
A total of 28 different measurement points, each with ten different wiring junction connections between the sensor and control system were subjected to vibration, moisture and heat, causing connection failures and changes in connection resistance that resulted in large measurement errors. Large chunks of slag could be ejected from the furnace—damaging cable or conduit up to 80 feet from the furnace. In addition, physical damage could occur each time the furnace top was opened to charge the furnace. Each week between 9 and 12 measurements would fail.
Switching to rugged Rosemount wireless temperature sensors that could reliably withstand the extreme temperature conditions—and remove wiring vulnerabilities altogether—eliminated the reliability problems, saving $200,000 in maintenance and repair expenses annually. More importantly, eliminating this source of downtime increased production capacity by nearly another full batch each day—and at $200,000 per batch, represented $50 million in "recaptured" production capacity.
At another extreme of challenging conditions, Perry's Ice Cream in Akron, N.Y., experienced persistent failures of its Coriolis and magmeter flow instrumentation caused by the plant's sanitary washdown procedures. Water repeatedly entered the flowmeter housings, causing the electronics to eventually fail. Since switching four years ago to Emerson's Rosemount Magmeters and Micro Motion Coriolis meters which are designed to withstand extreme operating conditions such as repeated washdowns, "I never have to worry about reliability," says Dave Foley, senior plant engineering technician.
Once your process instrumentation is no longer adding to downtime problems, you can start to enlist its detection and diagnostic capabilities to spot process conditions that may be early indicators of trouble. Indeed, Rosemount instrumentation comes equipped with a broad range of advanced diagnostic capabilities designed to help monitor the integrity of the instruments themselves as well as the health of equipment assets and related infrastructure.
These advanced diagnostics alert operators or other personnel to potential issues before they become disruptive. Dashboards and local displays deliver information in clear, concise language, conveying immediate understanding of the nature of any operational issue for quick resolution. And because the user-friendly interface is used consistently across a wide breadth of Emerson products, personnel can be more productive without having to learn a different interface for each type of instrument.