【国外标准】 Standard Test Method for Heat Aging of Asbestos Textiles (Withdrawn 2022)

4.1 This test method covers the evaluation of asbestos textiles with regard to (1) quality and (2) elevated temperature serviceability characteristics. Since asbestos textiles are usually composed of blends of asbestos with cotton or other organic carrier fibers, the latter being present in amounts up to 25 %, temperatures above 150°C [300°F] will promote the degradation of the cotton content and will reduce the structural reinforcement derived therefrom. In the higher grade asbestos textiles, wherein little or no carrier fibers are used and in which the longer asbestos fibers are necessary if a satisfactory yarn is to be produced, the degradation in strength resulting from heat-aging up to 540°C [1000°F] is low. In the case of the lower grade asbestos textiles, however, wherein amounts from 15 to 25 % carrier fibers are incorporated, asbestos fibers having shorter lengths may be utilized. Under the relatively low service temperatures to which such materials may be subjected, neither the cotton nor the cloth properties are greatly affected. However, the strength-imparting influence of the carrier fibers is reduced at elevated temperatures and the entwining properties of the shorter asbestos fibers primarily serve to establish the resultant tensile strength and other physical properties of the textile. In view of this, elevated temperature tests may serve to indicate the asbestos fiber grade or quality that may be used in a textile construction.4.2 Another use and perhaps more practical application for the information to be derived from elevated temperature studies is the revelation of the ability of a subject textile to withstand known elevated temperature service conditions. It will be appreciated that temperature alone may not be the only degratory influence in the destruction of such materials; however, under normal operating conditions, high temperatures are usually the dominating factors in such degradation. The results obtained through such investigations therefore may be interpreted in terms of elevated temperature serviceability.1.1 This test method covers the heat aging of asbestos textiles. It may be used to determine the resistance to the deterioration of tensile strength at temperatures up to 450°C [800°F].1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.1.3 Warning—Breathing of asbestos dust is hazardous. Asbestos and asbestos products present demonstrated health risks for users and for those with whom they come into contact. In addition to other precautions, when working with asbestos-cement products, minimize the dust that results. For information on the safe use of chrysoltile asbestos, refer to “Safe Use of Chrysotile Asbestos: A Manual on Preventive and Control Measures.”21.4 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. For specific safety hazard, see 1.3.1.5 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.