Thin sheets of iron or steel are rolled hot from bars about 8 inches wide known as sheet-bars. The sheet bars for this industry are rolled in the sheet-bar mill, not unlike the billet mill in Fig. 45, and the method of rolling them from the ingot or from the wrought-iron "pile" is similar to that mentioned for rolling rails. The ingot is rolled out into a long strip 8 inches wide and varying from 3/8 to 1 1/8 inches thick. This strip is cut into lengths of 30 feet for convenience in handling, and is shipped to the sheet mill, the work of which is described in the next chapter.

The skelp mill is a special sheet-bar mill for rolling steel or wrought iron bars or "skelp" for the manufacture of iron pipe.

Plates of steel of 1/4-inch or less in thickness are designated as sheets.