United States Steel is a steel producer of flat-rolled and tubular products with production operations in the United States and Europe. The company is also engaged in railroad services and real estate operations. The company's segments are: North American Flat-Rolled, which produces slabs, strip mill plates, sheets and tin mill products; U. S. Steel Europe, which produces and sells slabs, strip mill plate, sheet, tin mill products and spiral welded pipe, as well as heating radiators and refractory ceramic materials; and Tubular Products, which produces and sells electric resistance welded steel casing and tubing (known as oil country tubular goods), and standard and line pipe and mechanical tubing.