1.1 This classification categorizes machine-made refractory brick defined as chrome, chrome-magnesia, magnesia-chrome, and magnesia brick (see 3.1). It does not cover products made from electrically fused magnesium oxide or to products made by fusion casting. Its purpose is to describe classes distinguished by obvious differences in magnesium oxide (MgO) content except for chrome brick.

1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.