1.1 本规程中包含的数学方法提供了一个计算程序，用于在裸露阀门和法兰上添加隔热材料时估计热损失或热节省。 1.2 对于实际系统的适用性问题，应由熟悉绝缘系统设计和分析的合格人员解决。 1.3 估计精度受到以下限制: 1.3.1 绝缘材料和系统的物理性能数据的范围和质量， 1.3.2 裸阀和绝缘表面面积计算方法的准确性，以及工艺、制造和安装的质量。 1.4 该程序被认为适用于传统型绝缘系统和可拆卸/可重复使用的盖。在这两种情况下，为了传热计算的目的，假设绝缘系统是均质的。 1.5 本规程不打算建立使用隔热的设备设计所需的标准，也不建立或推荐所有表面的隔热适用性。 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和健康实践，并确定监管限制的适用性。 ====意义和用途====== 5.1 阀门隔热制造商通常在显示每个阀门热损失的图表中表示其产品的性能。这些数据针对不同管道尺寸、ANSI等级、绝缘类型、绝缘厚度和工作温度的裸阀和绝缘阀。 正确选择绝缘系统还需要关于风速、导管架发射度、裸阀发射度和环境条件影响的其他信息。由于管道尺寸、ANSI等级、绝缘类型和厚度、工作温度、绝缘盖几何形状、表面发射度值和环境条件的无限组合，不可能发布每种可能情况的数据。 5.2 管道系统隔热的用户面临着设计大型隔热管道系统的问题，为了获得所需的热信息，他们需要付出巨大的工程成本。 通过使用精确的工程数据表，或使用可用的计算机分析工具，或两者兼而有之，可以大幅降低成本。 5.3 阀门和法兰隔热的制造商、承包商和用户使用本规程将提供足够精度和一致性的标准化工程数据，用于预测裸露阀门和法兰隔热所节约的热能。 5.4 现在，大多数隔热生产商和消费者都可以随时使用计算机，以允许使用这种做法。 5.5 实践中的计算机程序 C680型 已开发用于计算裸管和绝缘管的单位长度或单位表面积的热损失。利用裸露阀门或法兰表面面积的值，可以估计热损失。通过根据绝缘制造商或承包商的图纸估算外绝缘表面面积，同样可以通过取每单位面积热损失的乘积（根据符合实践的程序）来计算绝缘表面的热损失 C680型 )以及阀门或法兰的绝缘表面积。还需要考虑未绝缘表面的面积。 5.6 本规程的使用要求阀门或法兰绝缘系统符合任一规范 C1695 用于可移除/可重用或辅助练习 C450 3. 用于由刚性板和管道保温材料制成的保温材料。

1.1 The mathematical methods included in this practice provide a calculational procedure for estimating heat loss or heat savings when thermal insulation is added to bare valves and flanges. 1.2 Questions of applicability to real systems should be resolved by qualified personnel familiar with insulation systems design and analysis. 1.3 Estimated accuracy is limited by the following: 1.3.1 The range and quality of the physical property data for the insulation materials and system, 1.3.2 The accuracy of the methodology used in calculation of the bare valve and insulation surface areas, and the quality of workmanship, fabrication, and installation. 1.4 This procedure is considered applicable both for conventional-type insulation systems and for removable/reuseable covers. In both cases, for purposes of heat transfer calculations, the insulation system is assumed to be homogenous. 1.5 This practice does not intend to establish the criteria required in the design of the equipment over which thermal insulation is used, nor does this practice establish or recommend the applicability of thermal insulation over all surfaces. 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 and health practices and determine the applicability of regulatory limitations prior to use. ====== Significance And Use ====== 5.1 Manufacturers of thermal insulation for valves typically express the performance of their products in charts and tables showing heat loss per valve. These data are presented for both bare and insulated valves of different pipe sizes, ANSI classes, insulation types, insulation thicknesses, and service temperatures. Additional information on effects of wind velocity, jacket emittance, bare valve emittance, and ambient conditions are also required to properly select an insulation system. Due to the infinite combination of pipe sizes, ANSI classes, insulation types and thicknesses, service temperatures, insulation cover geometries, surface emittance values, and ambient conditions, it is not possible to publish data for each possible case. 5.2 Users of thermal insulation for piping systems faced with the problem of designing large systems of insulated piping, encounter substantial engineering costs to obtain the required thermal information. This cost can be substantially reduced by both the use of accurate engineering data tables, or by the use of available computer analysis tools, or both. 5.3 The use of this practice by the manufacturer, contractor, and users of thermal insulation for valves and flanges will provide standardized engineering data of sufficient accuracy and consistency for predicting the savings in heating energy use by insulating bare valves and flanges. 5.4 Computers are now readily available to most producers and consumers of thermal insulation to permit use of this practice. 5.5 The computer program in Practice C680 has been developed to calculate the heat loss per unit length, or per unit surface area, of both bare and insulated pipe. With values for bare valve or flange surface areas, heat loss can be estimated. By estimating the outer insulation surface area from an insulation manufacturer's or contractor's drawings, the heat loss from the insulation surface can likewise be calculated by taking the product of heat loss per unit area (from programs conforming to Practice C680 ) and the valve or flange insulation surface area. The area of the uninsulated surfaces also will need to be considered. 5.6 The use of this practice requires that the valve or flange insulation system meets either Specification C1695 for removeable/reuseable or the Adjunct to Practice C450 3 for insulation fabricated from rigid board and pipe insulation.