At U.S. Steel, New Computers Revive Old PlantBy John McCormick | Posted 2002-06-15 Email Print
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Starting in 1998, U.S. Steel undertook a massive overhaul of the systems at its Mon Valley Works. How did the 126-year-old facility weather the changes?
Finding people at U.S. Steel's Mon Valley Works can be a challenge. At times, a manager can look from one end of the half-mile long plant to the other without seeing a single soul.
The floors on which 9,300 steelworkers once tended to blast furnaces and presses now stand virtually empty. Only 2,100 workers now man the plant, which casts 2.8 million tons of steel a year.
By and large, the throngs of steelworkers have been retired by computers and automated controls that now watch over every aspect of the steel-making process.
But computer systems age, too. In 1998, U.S. Steel's management decided to refurbish the Mon Valley Works. The $36 million modernization saw the replacement of computer, controls and mechanical equipment, in slightly more than a year. However, introducing new computers without massive disruption of production is no small task in a 126-year old steel factory.
Mon Valley is one of U.S. Steel's four mills—the others are the Fairfield Works in Birmingham, Ala.; the Fairness Works, in Fairness Hill, Pa.; and the Gary Works in Gary, Ind., the largest in North America.
Mon Valley is comprised of two, highly automated facilities, both located about 10 miles south of Pittsburgh in the Monongahela River valley.
The Edgar Thompson plant, built in 1875, is the mill's "hot end," where iron is melted at 3,300 degrees Fahrenheit and cast into steel slabs.
The slabs are carried to the Irvin plant (a finishing mill built in 1938), where they are reheated to more than 2,300 degrees Fahrenheit. They are then shot at 2,000 feet per second through a series of machines that first squeeze the steel with rollers into long, thin strips and then winds them into coils called hot bands. In both facilities, the din of metal hitting metal makes conversation nearly impossible. And the heat causes personal problems, as well.
"Deodorant is something you really need around here," says U.S. Steel's CIO Gene Trudell.
But the sweat can pay off. Last year, the Mon Valley factory was named "Plant of the Year" by the U.S. Department of Energy's Office of Industrial Technologies.
U.S. Steel brought in Alstom Power Conversion to help upgrade Mon Valley's Irvin plant, after Alstom helped with similar upgrades at Fairfield and Gary.
At Mon Valley, Alstom and U.S. Steel left much of the walls, floors and other physical plant, but replaced a number of mechanical devices—including the electromechanical screws that adjusted the rollers used to press steel, which were replaced by faster hydraulic devices—and enhanced the computer and control system.
Plant production is measured by how many tons per hour it processes. The upgrades boosted Irvin's production from 270 tons per hour to 335 tons an hour.
Before the upgrade, the mill's master controls resided on a Honeywell process control computer with General Electric analog and digital controls handling mill setup movements, including the speed at which steel was sent through the finishing line, as well as the line's tension and gauging. X-ray gauges monitored the thickness of the steel by passing a beam of radiation through a strip of steel and then measuring the amount of radiation that's absorbed.
But the Honeywell machine was an aging unit that ran mill setup programs—and hadn't been significantly enhanced in almost 20 years.
It was time for a change.
Alstom replaced the Honeywell and GE equipment with Compaq Alpha computers, which now run the modeling software and an Alstom programmable logic controller, which tracks the steel as it's processed. The aim: To run the mill faster and produce more product from the same amount of raw materials.
In addition, new gauges with laser sensors were installed to monitor the process and feed information back to the Compaq equipment. The lasers scan steel more quickly than x-rays to determine the thickness of a strip.
The upgrade came up cleanly. But there was nothing the systems people could do about the dirt and grime of the mill—which presented a problem for the laser equipment.
The lasers watch what's called mass flow control and slip compensation. Mass flow is a measure of the amount of material being processed. As the rollers reduce thickness, the mill needs to make sure squeezing the material is increasing the length of the slab, not the width. "Slip'' refers to the tension lost if the slab, for some reason, is pulled away from rollers.
The laser sensors were installed at critical points in the production process, such as when steel flows in and out of the stands that hold up the rollers.
Unfortunately, according to Frank Voelker, president and CEO of Alstom Power Conversion, the amount of dirt and vapor floating around the mill wasn't properly accounted for and the sensors, to date, have been blinded by the dirt. The companies are trying to find laser equipment that can see through the distractions.
But figuring out when to replace the software and hardware (computerized and non-computerized) presented the biggest challenge. Normally, during a plant upgrade this extensive, mills are shut down. The trick is to avoid a prolonged outage that would take the plant off line for a month or two.
Alstom and U.S. Steel came up with a plan. They would thoroughly test the computer and controls offline. They would test drive the equipment during regularly scheduled one-day maintenance outages. And they would let the new computer equipment "shadow" the Honeywell equipment, before the Honeywell equipment was turned off.
During this procedure, the Honeywell computer kept control of the operation, but as it processed commands it sent signals to the new equipment to perform the same tasks in a mock-up production environment. This allowed the team to assess how well the equipment would perform once it was online and to correct or fine-tune any deficiencies
Overall, the upgraded equipment let the mill better control output. Feedback from sensors throughout the plant let systems quickly and accurately figure out when to stop the mill to shear, or cut, strips to the desired coil size or weight. This alone improved the mill speed by 25 tons an hour.
Mill production, before the upgrade of information systems, averaged 270 tons an hour. A week after the work was complete, the average was up to 294 tons and by February 2001 it hit 335 tons an hour, a pace it's managed to maintain.
Major disruptions never came. Switching over computer and control switches mean taking the plant down for a total of 36 days. But no part of that switchover meant more than seven consecutive days of downtime.
And at no time during any phase of the installation was the complex shut down for more than 10 days in a row.