The L-1 system also provides information about one furnace operation to the other two furnaces. Operators formerly predicted exit temperatures based on experiential knowledge. Because of the models, slab temperatures are more consistent as slabs enter the hot-strip mill, WCI managers say. A temperature gage just before the finishing train checks slab temperatures. The pusher-type furnaces have received only minor upgrades in the past few years.
New controls allow operators to change heating temperatures faster.
The units are better maintained than in the past. Reheated slabs per turn have increased from 5,400 tons three years ago to 6,400 tons today, says Frank Zedalis, a reheat engineer at Gary Works. Three years ago, maintenance crews began a 60-day recalibration schedule for each furnace. They check every burner-flow meter and pressure control to make sure they're reading gas input properly. Pulpit operators use the meters to make adjustments to reheat temperatures.