This reduces the need to look at the strip visually on a re-inspection unit. Other mills have installed this system on coating lines, but not on temper mills. The system has helped the plant reduce holes by 20 percent in the past year. The hole-detection information is stored in a computer. Looking at patterns, operators can superimpose holes from several coils on top of each other.
Holes have a lot of sources.
Just about every point from the caster to the cold mill can be a source of holes. The finishing facility of North Star Steel's Houston, Tex. The mill heat-treats and finishes the end couplings for up to 300,000 annual tons of pipe manufactured at North Star's Youngstown, Ohio, mill. All the steel from Houston is used in oil and natural-gas exploration. Previously, the UT and EM inspections were conducted independently of each other in separate buildings.