4.1 This classification categorizes the defined types of fused-cast refractory blocks and shapes into distinct classes based on mineralogical composition. Such classes have historically been useful for relating the defined types and classes with specific industrial applications and for developing product or purchasing specifications.

1.1 This classification covers commercial fusion-cast refractory blocks and shapes. Its purpose is to set forth the various types and classes of these materials according to their mineralogical compositions. These compositions are important to determining their suitability for use in specified applications. This standard is not intended to cover commercial fused grains or beads.

1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.

1.3 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.