1.1 本指南涵盖了选择隔热护套材料的标准，并不打算用作性能或产品规范。 1.2 本指南适用于管道、导管和设备隔热层上的护套材料。 1.3 本指南包括隔热层上使用的护套材料，无论隔热层是以管道、板或毯子的形式，还是自支撑的现场应用材料，包括隔热水泥。 1.4 本指南不包括包含松散填料、其他非支撑绝缘材料或埋地绝缘系统导管或容器的盖子或其他挡土墙。 1.5 本指南不包括胶粘剂和涂料及其增强材料。 1.6 以英寸-磅为单位的数值应视为标准值。括号中给出的值是到国际单位制的数学转换，仅供参考，不被视为标准值。 1.7 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.8 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 4.1 本标准旨在为工程师和设计师提供指导，帮助他们选择合适的隔热护套材料。作为指南，它可用于确定特定绝缘护套系统可能需要的性能特征。 本指南不是规范，因此不应作为规范使用。然而，它在编写规范时可能有用。规格 C921 也可用于确定隔热护套材料的性能。

1.1 This guide covers criteria for selecting thermal insulation jacketing materials and is not intended for use as a performance or product specification. 1.2 This guide applies to jacketing materials applied over thermal insulation for piping, ducts, and equipment. 1.3 This guide includes jacketing materials used over thermal insulation whether the insulation is in the form of pipe, board, or blanket, or field applied materials that are self-supporting, including insulating cements. 1.4 This guide does not include covers or other retaining walls that contain loose fill, other nonsupporting insulation materials, or conduits or containers for buried insulation systems. 1.5 This guide does not include mastics and coatings and their reinforcements. 1.6 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. 1.7 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. 1.8 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. ====== Significance And Use ====== 4.1 This standard is intended to be used by engineers and designers as a guide to assist them in selecting appropriate thermal insulation jacketing materials. As a guide, it can be used to identify performance characteristics that might be necessary for a particular insulation jacketing system. This guide is not a specification and therefore should not be used as such. It might, however, be useful in writing a specification. Specification C921 can also be used to determine properties of jacketing materials for thermal insulation.