【国外标准】 Standard Practice for Determining the Maintenance Factor (m) and Yield Factor (y) Loading Constants Applicable to Gasket Materials and Designs

4.1 The gasket factors are a function of leak rate; therefore, this practice generates curves. Constants for use in the ASME Boiler and Pressure Vessel Code, Section VIII, Appendix 2 code calculations are selected from these data. Specific m and y values can be selected based on a maximum desired leak rate or derived from these data as described in this procedure. This practice addresses the influence of leak rate and gasket thickness on a gasket’s ability to provide a seal initially and in operation. This practice is performed at room temperature; therefore, this practice does not account for all conditions, such as high temperature or thermal cycling or both, that bolted flange connections may be subject to in field application.4.2 This practice determines two general characteristics that are specific to the ASME design criteria. Caution should be exercised when comparing yield and maintenance factors between gasket materials, and it is recommended that the m and y curves be compared. Selecting a gasket material for use in an application should not be based exclusively on these two general characteristics. Gasket material selection for a given application should consider additional information not described in this practice, which includes, but is not limited to, chemical resistance, thermal resistance, creep relaxation, compressibility, and accommodation of thermal cycling.4.3 This practice builds upon work conducted in the Fluid Sealing Association (FSA G 605:11). The associated round robin data is provided for reference in Tables 1-4.(A) BDL = below detection limit.(A) BDL = below detection limit.1.1 This practice will establish criteria for determining loading constants that are referenced in the American Society of Mechanical Engineers (ASME) pressure vessel design (Boiler and Pressure Vessel Code, Section VIII, Divs. 1 and 2). These constants are specific to this design criterion for metallic, semi-metallic, and nonmetallic gaskets.1.2 Units—The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.4 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.