Open main menu
An example of a heat number on a plate.

A heat number is an identification coupon number that is stamped on a material plate after it is removed from the ladle and rolled at a steel mill.

Industry quality standards require materials to be tested at the manufacturer and the results of these tests be submitted through a report, also called a Mill Sheet, Mill Certificate or Mill Test Certificate (MTC). The only way to trace a steel plate back to its Mill Sheet is the Heat Number. A heat number is similar to a lot number, which is used to identify production runs of any other product for quality control purposes.

Numerical significanceEdit

Usually, but not universally, the numbers indicate:

  • the first digit corresponds to the furnace number
  • the second digit indicates the year in which the material was melted
  • the last three (and sometimes four) indicate the melt number.