1.1 This practice covers the minimum requirements for installing clay flue lining as a lining for residential masonry chimneys not exceeding 40 ft (12.2 m) in height. 1.2 In developing the metric conversions used in the standards under the jurisdiction of Committee C-4, recognition has been made of the variable nature of clays, so that neither "soft" nor "hard" conversions, as they are defined in Practice E380, have been made. For example, the inch is considered to be 25 mm instead of 25.4 mm. 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.