1.1 本试验方法涵盖了管道隔热层稳态传热财产的测量。试样类型包括刚性、柔性和松散填充；均质和非均质；各向同性和非各向同性；圆形或非圆形横截面。包括金属反射绝缘和具有金属护套或其他高轴向电导元件的质量绝缘的测量；但是，必须采取额外的预防措施，并且必须遵循特定的特殊程序。 1.2 用于此目的的试验装置为保护端或校准端管道装置。防护端装置是一种主要（或绝对）方法。防护端方法与ISO具有可比性，但不完全相同 ISO方法不使用实践中的计算程序 第1045页 . 1.3 以国际单位制或英寸磅单位表示的数值应单独视为标准。 每个系统中规定的值可能不是精确的等效值；因此，每个系统应独立于其他系统使用。将两个系统的值组合在一起可能会导致不符合标准。 1.4 适当时，或根据规范或其他试验方法的要求，可根据测量数据计算试样的以下热传递财产（参见 3.2 ): 1.4.1 管道绝缘线性热阻和导热系数， 1.4.2 管道保温线性热传递， 1.4.3 表面面积电阻和传热系数， 1.4.4 热阻率和电导率， 1.4.5 面热阻和导热系数，以及 1.4.6 面积热传递。 注1: 在这种测试方法中，优选的电阻、电导和迁移是为单位长度的管道计算的线性值。不得将这些与基于单位面积计算的相应面积财产混淆，后者更适用于平板几何图形。 如果计算这些面积财产，则必须报告计算中使用的面积。 注2: 关于这些财产对特定试样或材料的适用性的讨论，请参见测试方法 1977年 ，测试方法 第518页 ，以及在文献中 ( 1. ) . 2. 1.5 该测试方法允许在较宽的温度范围内进行操作。管道表面温度的上限和下限由试样或用于制造设备的材料的最高和最低使用温度决定。在任何情况下，必须操作该设备，使得暴露表面和环境之间的温差足够大，足以提供所需的测量精度。通常情况下，设备在15-30°C的严格控制的静止空气环境中运行，但其他温度、其他气体和其他速度也是可以接受的。 通过使用加热或冷却的外护套或毯子或通过使用额外的均匀绝缘层来控制外部试样表面温度也是可以接受的。 1.6 允许使用任何尺寸或形状的测试管，前提是它与待测试的试样相匹配。通常情况下，测试方法用于圆形管道；然而，允许将其用于非圆形横截面的管道（正方形、矩形、六角形等）。实验室间比较常用的一种尺寸是直径为88.9mm的圆形横截面管道（标准标称尺寸为80mm[3-in.]的管道尺寸），尽管文献中报道了其他几种尺寸 ( 2- 4. ) . 1.7 该试验方法仅适用于具有水平轴或垂直轴的试验管道。对于横轴，文献包括使用防护端、校准端和校准端盖方法。 对于垂直轴，没有发现任何经验支持使用校准或校准的末端方法。因此，该方法仅限于使用防护端管设备进行垂直轴测量。 1.8 该试验方法涵盖了两种截然不同的管道设备，即防护端和校准或计算端，这两种设备在试验段末端的轴向传热处理上有所不同。 1.8.1 防护端设备在每一端使用单独加热的防护段，这些防护段被控制在与测试段相同的温度下，以限制轴向热传递。这种类型的仪器优选用于本试验方法范围内的所有类型的试样，并且必须用于包含高轴向电导元件的试样。 1.8.2 校准或计算的端部设备在测试段的每一端使用绝缘端盖，以最大限度地减少轴向热传递。 基于试验条件下端盖校准或使用已知材料财产进行计算的修正适用于测量的试验段传热。这些仪器不适用于对具有高轴向电导元件（如反射绝缘或金属护套）的试样进行测试。在使用这些设备进行使用垂直轴的测量方面没有已知的经验。 1.9 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的使用者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。 1.10 本国际标准是根据世界贸易组织技术性贸易壁垒委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认的标准化原则制定的。 ====意义和用途====== 4.1 根据该试验方法确定，管道绝缘线性热阻或导热系数（以及适用时的热阻或导热率）是比较绝缘的方法，包括绝缘及其对管道的配合、圆周和纵向连接以及结构变化的影响，但不包括外表面电阻或传热系数的影响。因此，当绝缘外表面温度和管道温度已知或规定时，它们是合适的。然而，由于本试验方法确定的热财产包括配合和接合的影响，因此它们不是真正的材料财产。因此，本试验方法测定的财产与使用防护热板（试验方法）在平面形状的明显类似材料上获得的性能略有不同 1977年 ，或热流计设备，试验方法 第518页 . 4.2 管道隔热线性热传递既包括隔热效果及其对管道的配合，也包括表面传热系数的影响。当已知或规定环境条件和管道温度，并考虑表面的热效应时，这是合适的。 4.3 由于本试验方法中规定的试验条件要求，认识到获得的热传递财产不一定是所有使用条件下的相关值。例如，本试验方法规定，应通过对干燥或调节过的试样进行试验来获得热财产，而这些条件不一定在使用中实现。所获得的结果仅严格适用于测试条件和测试的产品结构，当材料在其他条件下使用时，如平均温度与测试温度明显不同，在没有适当调整的情况下不得使用。 考虑到这些资格，以下内容适用: 4.3.1 对于在相同环境中运行的相同尺寸和温度的水平或垂直管道，通过该试验方法获得的值可用于几个试样的直接比较，用于与规范值进行比较，以及用于估计与测试样品相同的样品实际应用的热损失的工程数据（包括任何护套或表面处理）。在适当的情况下，纠正端部接头和其他反复出现的不规则现象的影响( 4.4 ). 4.3.2 当将结果应用于不同于测试中使用的绝缘尺寸时，需要进行适当的数学分析。对于均质材料，这包括使用热导率或电阻率值（针对平均温度的任何变化进行校正），以及在考虑环境温度时使用表面传热系数（例如，见实践 C680 ). 对于非均匀和反射隔热材料，需要一个更详细的数学模型，该模型能够正确地考虑各个传热模式（传导、对流、辐射）以及每个模式随管道尺寸、隔热厚度和温度变化的变化。 4.4 由于空气腔的几何形状和方向会影响对流传热，因此很难测量包含空气腔的反射绝缘的热性能。虽然总是希望测试全长管段，但由于现有管道绝缘测试仪的尺寸限制，这并不总是可能的。如果绝缘部分的测试长度小于全长，内部对流传热通常会发生变化，这将影响测量性能。因此，必须认识到，测得的热性能小于满- 长度绝缘部分不一定代表全长部分。 4.5 防护端管装置的设计基于试样、试验管、加热器以及计量段和防护段之间的其他导热路径中可忽略的轴向热流。为了防止轴向热流，通常在防护间隙上方的末端修改一些不均匀的反射隔热层。尽可能避免这些修改，但对于一些不均匀的隔热设计，它们提供了唯一的方法来满足防护间隙中可忽略不计的热流假设。因此，在具有修改端的绝缘试样上测量的热性能不一定代表标准绝缘截面的性能。 4.6 可以使用此试验方法，通过比较两个试样的试验来确定端部接头或其他孤立不规则性的影响，其中一个试样在整个长度上是均匀的，另一个试样包含试验段内的接头或其他不规则性。 这两种测试之间的热损失差异，针对接缝或其他不规则性覆盖的均匀区域进行校正，即引入的额外热损失。必须注意在管道和环境温度相同的条件下进行试验，并且接头或不规则处与试验段端部之间有足够的长度，以防止明显的端部损失。 4.7 为了获得符合本试验方法的满意结果，必须遵循本试验方法中所述仪器的结构和使用原则。如果报告的结果是通过本试验方法获得的，则应满足本试验方法中规定的所有相关要求，或在报告中描述任何例外情况。 4.8 在这种类型的测试方法中，建立结构和程序的细节以涵盖所有可能给没有热流理论、温度测量和一般测试实践技术知识的人带来困难的意外情况是不可行的。 该测试方法的标准化并不能减少对此类技术知识的需求。人们还认识到，由于这种测试方法的标准化，限制研究人员进一步开发改进的或新的方法或程序是不明智的。 图1 防护端设备 注4: 当在低于正常室温的环境温度下进行测试时，理论分析表明，实验热流方向对于完全均匀的材料来说并不重要。然而，如果绝缘材料的财产在径向变化，则实验热流方向将显著影响测量的导热系数。在使用径向热流向外实验的数据进行径向热流向内应用时，要格外小心。

1.1 This test method covers the measurement of the steady-state heat transfer properties of pipe insulations. Specimen types include rigid, flexible, and loose fill; homogeneous and nonhomogeneous; isotropic and nonisotropic; circular or non-circular cross section. Measurement of metallic reflective insulation and mass insulations with metal jackets or other elements of high axial conductance is included; however, additional precautions must be taken and specified special procedures must be followed. 1.2 The test apparatus for this purpose is a guarded-end or calibrated-end pipe apparatus. The guarded-end apparatus is a primary (or absolute) method. The guarded-end method is comparable, but not identical to ISO 8497. The ISO method does not use the calculation procedure in Practice C1045 . 1.3 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. 1.4 When appropriate, or as required by specifications or other test methods, the following thermal transfer properties for the specimen can be calculated from the measured data (see 3.2 ): 1.4.1 The pipe insulation lineal thermal resistance and conductance, 1.4.2 The pipe insulation lineal thermal transference, 1.4.3 The surface areal resistance and heat transfer coefficient, 1.4.4 The thermal resistivity and conductivity, 1.4.5 The areal thermal resistance and conductance, and 1.4.6 The areal thermal transference. Note 1: In this test method the preferred resistance, conductance, and transference are the lineal values computed for a unit length of pipe. These must not be confused with the corresponding areal properties computed on a unit area basis which are more applicable to flat slab geometry. If these areal properties are computed, the area used in their computation must be reported. Note 2: Discussions of the appropriateness of these properties to particular specimens or materials may be found in Test Method C177 , Test Method C518 , and in the literature ( 1 ) . 2 1.5 This test method allows for operation over a wide range of temperatures. The upper and lower limit of the pipe surface temperature is determined by the maximum and minimum service temperature of the specimen or of the materials used in constructing the apparatus. In any case, the apparatus must be operated such that the temperature difference between the exposed surface and the ambient is sufficiently large enough to provide the precision of measurement desired. Normally the apparatus is operated in closely controlled still air ambient from 15 to 30°C, but other temperatures, other gases, and other velocities are acceptable. It is also acceptable to control the outer specimen surface temperature by the use of a heated or cooled outer sheath or blanket or by the use of an additional uniform layer of insulation. 1.6 The use any size or shape of test pipe is allowable provided that it matches the specimens to be tested. Normally the test method is used with circular pipes; however, its use is permitted with pipes or ducts of noncircular cross section (square, rectangular, hexagonal, etc.). One common size used for interlaboratory comparison is a pipe with a circular cross section of 88.9-mm diameter (standard nominal 80-mm [3-in.] pipe size), although several other sizes are reported in the literature ( 2- 4 ) . 1.7 The test method applies only to test pipes with a horizontal or vertical axis. For the horizontal axis, the literature includes using the guarded-end, the calibrated, and the calibrated-end cap methods. For the vertical axis, no experience has been found to support the use of the calibrated or calibrated-end methods. Therefore the method is restricted to using the guarded-end pipe apparatus for vertical axis measurements. 1.8 This test method covers two distinctly different types of pipe apparatus, the guarded-end and the calibrated or calculated-end types, which differ in the treatment of axial heat transfer at the end of the test section. 1.8.1 The guarded-end apparatus utilizes separately heated guard sections at each end, which are controlled at the same temperature as the test section to limit axial heat transfer. This type of apparatus is preferred for all types of specimens within the scope of this test method and must be used for specimens incorporating elements of high axial conductance. 1.8.2 The calibrated or calculated-end apparatus utilizes insulated end caps at each end of the test section to minimize axial heat transfer. Corrections based either on the calibration of the end caps under the conditions of test or on calculations using known material properties, are applied to the measured test section heat transfer. These apparatuses are not applicable for tests on specimens with elements of high axial conductance such as reflective insulations or metallic jackets. There is no known experience on using these apparatuses for measurements using a vertical axis. 1.9 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. 1.10 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 As determined by this test method, the pipe insulation lineal thermal resistance or conductance (and, when applicable, the thermal resistivity or conductivity) are means of comparing insulations which include the effects of the insulation and its fit upon the pipe, circumferential and longitudinal jointing, and variations in construction, but do not include the effects of the outer surface resistance or heat transfer coefficient. They are thus appropriate when the insulation outer-surface temperature and the pipe temperature are known or specified. However, since the thermal properties determined by this test method include the effects of fit and jointing, they are not true material properties. Therefore, properties determined by this test method are somewhat different from those obtained on apparently similar material in flat form using the guarded hot plate, Test Method C177 , or the heat flow meter apparatus, Test Method C518 . 4.2 The pipe insulation lineal thermal transference incorporates both the effect of the insulation and its fit upon the pipe and also the effect of the surface heat-transfer coefficient. It is appropriate when the ambient conditions and the pipe temperature are known or specified and the thermal effects of the surface are to be included. 4.3 Because of the test condition requirements prescribed in this test method, recognize that the thermal transfer properties obtained will not necessarily be the value pertaining under all service conditions. As an example, this test method provides that the thermal properties shall be obtained by tests on dry or conditioned specimens, while such conditions are not necessarily realized in service. The results obtained are strictly applicable only for the conditions of test and for the product construction tested, and must not be applied without proper adjustment when the material is used at other conditions, such as mean temperatures that differ appreciably from those of the test. With these qualifications in mind, the following apply: 4.3.1 For horizontal or vertical pipes of the same size and temperature, operating in the same ambient environment, values obtained by this test method can be used for the direct comparison of several specimens, for comparison to specification values, and for engineering data for estimating heat loss of actual applications of specimens identical to those tested (including any jackets or surface treatments). When appropriate, correct for the effect of end joints and other recurring irregularities ( 4.4 ). 4.3.2 When applying the results to insulation sizes different from those used in the test, an appropriate mathematical analysis is required. For homogeneous materials, this consists of the use of the thermal conductivity or resistivity values (corrected for any changes in mean temperature) plus the use of the surface heat transfer coefficient when the ambient temperature is considered (for example, see Practice C680 ). For nonhomogeneous and reflective insulation materials, a more detailed mathematical model is required which properly accounts for the individual modes of heat transfer (conduction, convection, radiation) and the variation of each mode with changing pipe size, insulation thickness, and temperature. 4.4 It is difficult to measure the thermal performance of reflective insulation that incorporate air cavities, since the geometry and orientation of the air cavities can affect convective heat transfer. While it is always desirable to test full-length pipe sections, this is not always possible due to size limitations of existing pipe insulation testers. If insulation sections are tested less than full length, internal convective heat transfer are usually altered, which would affect the measured performance. Therefore, it must be recognized that the measured thermal performance of less than full-length insulation sections is not necessarily representative of full-length sections. 4.5 The design of the guarded-end pipe apparatus is based upon negligible axial heat flow in the specimen, the test pipe, heaters, and other thermal conductive paths between the metering and guard sections. Some nonhomogeneous and reflective insulation are usually modified at the end over the guard gap in order to prevent axial heat flow. Avoid these modifications where possible, but for some nonhomogeneous insulation designs, they provide the only means to satisfy the negligible heat flow assumption across the guard gaps. Therefore, thermal performance measured on insulation specimens with modified ends are not necessarily representative of the performance of standard insulation sections. 4.6 It is acceptable to use this test method to determine the effect of end joints or other isolated irregularities by comparing tests of two specimens, one of which is uniform throughout its length and the other which contains the joint or other irregularity within the test section. The difference in heat loss between these two tests, corrected for the uniform area covered by the joint or other irregularity, is the extra heat loss introduced. Care must be taken that the tests are performed under the same conditions of pipe and ambient temperature and that sufficient length exists between the joint or irregularity and the test section ends to prevent appreciable end loss. 4.7 For satisfactory results in conformance with this test method, the principles governing construction and use of apparatus described in this test method must be followed. If the results are to be reported as having been obtained by this test method, then all the pertinent requirements prescribed in this test method shall be met or any exceptions shall be described in the report. 4.8 It is not practical in a test method of this type to establish details of construction and procedure to cover all contingencies that might offer difficulties to a person without technical knowledge concerning the theory of heat flow, temperature measurements, and general testing practices. Standardization of this test method does not reduce the need for such technical knowledge. It is recognized also that it would be unwise to restrict the further development of improved or new methods or procedures by research workers because of standardization of this test method. FIG. 1 Guarded-End Apparatus Note 4: When testing at ambient temperatures below normal room temperatures, theoretical analysis shows that the experimental heat flow direction is unimportant for a perfectly homogenous material. However, if the properties of the insulation vary in the radical direction, the experimental heat flow direction will significantly affect the measured thermal conductivity. Exercise great care when using data from a radial heat flow outward experiment for a radial heat flow inward application.