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 –,183 to 104°,C [–,297 to 220°,F], Grade 2 covers material used on industrial systems with operating temperatures from –,183 to 150°,C [–,297 to 300°,F], and Grade 3 covers material used on industrial systems with operating temperatures from –,183 to 120°,C [–,297 to 250°,F] where halogens are not permitted.