1.1 This specification covers preformed flexible elastomeric cellular thermal insulation in sheet and tubular form. Grade 1 covers materials to be used on commercial or industrial systems with operating temperatures from -57 to 104°C (-70 to 220 °F), Grade 2 covers material used on industrial systems with operating temperatures from -40 to 175°C (-40 to 350°F), and Grade 3 covers material used on industrial systems with operating temperatures from -40 to 120°C (-40 to 250°F) where halogens are not permitted. 1.2 The values stated in SI units are to be regarded as the standard. The inch-pound equivalents of SI units, given in parentheses, are approximate. 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 and health practices and determine the applicability of regulatory limitations prior to use.