pound per inch

Pounds per inch is the steel coil trade's working unit, where it goes by PIW, pounds per inch of width. Divide a coil's weight by its width and you know whether a crane, a slitter or a recoiler mandrel can take it, because coil handling equipment is rated in exactly those terms: 1,000 PIW is a common ceiling, at which a 60 inch wide coil weighs 60,000 pounds. Mills push PIW as high as the customer's equipment tolerates, since heavier coils mean fewer coil changes on the processing line.

The same number shows up in bar and section weight. Steel at 0.284 pounds per cubic inch means a bar with one square inch of cross-section weighs 0.284 pounds per inch of length, so weight per inch is simply cross-sectional area times that constant, and the lb/in³ density entry elsewhere in this catalog is the other half of the calculation. In SI terms one pound per inch is nearly 18 kilograms per metre, well into heavy-cable territory.

Web handling, tape and extrusion use the unit for throughput and tension budgeting, where product is bought by weight and processed by length. The mass converters here move it to kg/m or pounds per foot directly, and the caution on this page about the three unrelated meanings of "lb/in" is worth reading before trusting any datasheet that prints it.