1、Designation: C335/C335M 101C335/C335M 17Standard Test Method forSteady-State Heat Transfer Properties of Pipe Insulation1This standard is issued under the fixed designation C335/C335M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision
2、, the year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1 NOTEThe designation was edit
3、orially corrected from C335/C355M to C335/C335M in January 2011.1. Scope1.1 This test method covers the measurement of the steady-state heat transfer properties of pipe insulations. Specimen typesinclude rigid, flexible, and loose fill; homogeneous and nonhomogeneous; isotropic and nonisotropic; cir
4、cular or non-circular crosssection. Measurement of metallic reflective insulation and mass insulations with metal jackets or other elements of high axialconductance is included; however, additional precautions must be taken and specified special procedures must be followed.1.2 The test apparatus for
5、 this purpose is a guarded-end or calibrated-end pipe apparatus. The guarded-end apparatus is aprimary (or absolute) method. The guarded-end method is comparable, but not identical to ISO 8497.1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The
6、 values stated in eachsystem may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from thetwo systems may result in non-conformance with the standard.1.4 When appropriate, or as required by specifications or other test methods, the following
7、 thermal transfer properties for thespecimen 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
8、 resistivity and conductivity,1.4.5 The areal thermal resistance and conductance, and1.4.6 The areal thermal transference.NOTE 1In this test method the preferred resistance, conductance, and transference are the lineal values computed for a unit length of pipe. These mustnot be confused with the cor
9、responding areal properties computed on a unit area basis which are more applicable to flat slab geometry. If these arealproperties are computed, the area used in their computation must be reported.NOTE 2Discussions of the appropriateness of these properties to particular specimens or materials may
10、be found in Test Method C177, Test MethodC518, and in the literature (1).21.5 This test method allows for operation over a wide range of temperatures. The upper and lower limit of the pipe surfacetemperature is determined by the maximum and minimum service temperature of the specimen or of the mater
11、ials used inconstructing the apparatus. In any case, the apparatus must be operated such that the temperature difference between the exposedsurface and the ambient is sufficiently large enough to provide the precision of measurement desired. Normally the apparatus isoperated in closely controlled st
12、ill air ambient from 15 to 30C, but other temperatures, other gases, and other velocities areacceptable. It is also acceptable to control the outer specimen surface temperature by the use of a heated or cooled outer sheathor blanket or by the use of an additional uniform layer of insulation.1.6 The
13、use any size or shape of test pipe is allowable provided that it matches the specimens to be tested. Normally the testmethod 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 int
14、erlaboratory comparison is a pipe with a circular cross section of88.9-mm diameter (standard nominal 80-mm 3-in. pipe size), although several other sizes are reported in the literature (2-4).1 This test method is under the jurisdiction of ASTM Committee C16 on Thermal Insulation and is the direct re
15、sponsibility of Subcommittee C16.30 on ThermalMeasurement.Current edition approved June 1, 2005May 1, 2017. Published October 2010October 2017. Originally approved in 1954. Last previous edition approved in 20052010 asC335 05aC335/C335M 101. DOI: 10.1520/C0335_C0335M-10E01.10.1520/C0335_C0335M-17.2
16、The boldface numbers in parentheses refer to the references at the end of this test method.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possibl
17、e to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West
18、Conshohocken, PA 19428-2959. United States11.7 The test method applies only to test pipes with a horizontal or vertical axis. For the horizontal axis, the literature includesusing the guarded-end, the calibrated, and the calibrated-end cap methods. For the vertical axis, no experience has been found
19、 tosupport the use of the calibrated or calibrated-end methods. Therefore the method is restricted to using the guarded-end pipeapparatus 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-endt
20、ypes, 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 sametemperature as the test section to limit axial heat transfer. This type of apparatus is pre
21、ferred for all types of specimens within thescope 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 heattransfer. Correctio
22、ns based either on the calibration of the end caps under the conditions of test or on calculations using knownmaterial properties, are applied to the measured test section heat transfer. These apparatuses are not applicable for tests onspecimens with elements of high axial conductance such as reflec
23、tive insulations or metallic jackets. There is no known experienceon 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 responsibilityof the user of this standard to estab
24、lish appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use.1.10 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Pri
25、nciples for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:3C168 Terminology Relating to Thermal InsulationC177 Test Method for Steady-State Heat Flux M
26、easurements and Thermal Transmission Properties by Means of theGuarded-Hot-Plate ApparatusC302 Test Method for Density and Dimensions of Preformed Pipe-Covering-Type Thermal InsulationC518 Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus3 For ref
27、erencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.TABLE 1 Conversion Factors (International Table)NOTE 1For thermal cond
28、uctance per unit length or thermal transference per unit length, use the inverse of the table for thermal resistance per unitlength. For thermal resistivity, use the inverse of the table for thermal conductivity. For thermal conductance (per unit area) or thermal transference (perunit area), use the
29、 inverse of the table for thermal resistance (per unit area).Thermal Resistance per Unit LengthAKmW1(B) KcmW1 Kcmscal1 Kmhkg-cal1 FfthBtu 11 KmW1 = 1.000 100.0 418.7 1.163 1.7311 KcmW1 = 1.000 10 2 1.000 4.187 1.163 10 2 1.731 1021 Kcmscal1 = 2.388 10 3 0.2388 1.000 2.778 10 3 4.134 1031 Kmhkg-cal 1
30、 = 0.8598 85.98 360.0 1.000 1.4881FfthBtu 1 = 0.5778 57.78 241.9 0.6720 1.000Thermal ConductivityAWm1K1(B) Wcm1K1 cals1cm1K1 kg-calh1m1K1 Btuh1ft 1F1 Btuin.h1ft2F11 Wm1K 1 = 1.000 1.000 102 2.388 103 0.8598 0.5778 6.9331 Wcm1K 1 = 100.0 1.000 0.2388 85.98 57.78 693.31 cals1cm 1K1 = 418.7 4.187 1.000
31、 360.0 241.9 2903.1 kg-calh1m 1K1 = 1.163 1.163 102 2.778 103 1.000 0.6720 8.0641 Btuh1ft 1F1 = 1.731 1.731 102 4.134 103 1.488 1.000 12.001 Btuin.h1ft2F1 = 0.1442 1.442 103 3.445 104 0.1240 8.333 102 1.000Thermal Resistance per Unit AreaAKm2W1( B) Kcm2W1 Kcm2scal 1 Km2hkg-cal 1 Fft2hBtu11 Km2W1 = 1
32、.000 1.000 104 4.187 104 1.163 5.6781 Kcm2W1 = 1.000 104 1.000 4.187 1.163 104 5.678 1041 Kcm2scal 1 = 2.388 105 0.2388 1.000 2.778 105 1.356 1041 Km2hkg-cal 1 = 0.8598 8.594 103 3.600 104 1.000 4.8821Fft2hBtu 1 = 0.1761 1.761 103 7.373 103 0.2048 1.000A Units are given in terms of (1) the absolute
33、joule per second or watt, (2) the calorie (International Table) = 4.1868 J, or the British thermal unit (InternationalTable) = 1055.06 J.B This is the SI (International System of Units) unit.C335/C335M 172C680 Practice for Estimate of the Heat Gain or Loss and the Surface Temperatures of Insulated F
34、lat, Cylindrical, and SphericalSystems by Use of Computer ProgramsC870 Practice for Conditioning of Thermal Insulating MaterialsC1045 Practice for Calculating Thermal Transmission Properties Under Steady-State ConditionsC1058 Practice for Selecting Temperatures for Evaluating and Reporting Thermal P
35、roperties of Thermal InsulationE230 Specification and Temperature-Electromotive Force (EMF) Tables for Standardized Thermocouples2.2 ISO Standards:ISO 8497 Thermal Insulation-Dermination of Steady State Thermal Transmission Properties of Thermal Insulation for CircularPipes2.3 ASTM Adjuncts:4Guarded
36、-end ApparatusCalibrated-end Apparatus3. Terminology3.1 DefinitionsFor definitions of terms used in this test method, refer to Terminology C168.3.2 Definitions of Terms Specific to This Standard:3.2.1 areal thermal conductance, Cthe steady-state time rate of heat flow per unit area of a specified su
37、rface (Note 3) dividedby the difference between the average pipe surface temperature and the average insulation outer surface temperature. It is thereciprocal of the areal thermal resistance, R.C 5 QAto 2t 2!5 1R (1)where the surface of the area, A, must be specified (usually the pipe surface or som
38、etimes the insulation outer surface).NOTE 3The value of C, the areal thermal conductance, is arbitrary since it depends upon an arbitrary choice of the area, A. For a homogeneousmaterial for which the thermal conductivity is defined as in 3.2.7 (Eq 8), the areal conductance, C, is given as follows:C
39、 5 2piLpAlnr2/ro!(2)If the area is specially chosen to be the “log mean area,” equal to 2piL (r2 ro)/l n(r2/ro), then C = p/(r2 ro). Since(r2 ro) is equal to the insulation thickness measured from the pipe surface, this is analogous to the relation between conduc-tance and conductivity for flat slab
40、 geometry. Similar relations exist for the areal thermal resistance defined in 3.2.2. Sincethese areal coefficients are arbitrary, and since the area used is often not stated, thus leading to possible confusion, it is recom-mended that these areal coefficients not be used unless specifically request
41、ed.3.2.2 areal thermal resistance, Rthe average temperature difference between the pipe surface and the insulation outer surfacerequired to produce a steady-state unit rate of heat flow per unit area of a specified surface (Note 3). It is the reciprocal of the arealthermal conductance, C.R 5Ato 2t 2
42、!Q 51C (3)where the surface of the area, A, must be specified (usually the pipe surface or sometimes the insulation outer surface).3.2.3 areal thermal transference, Trthe time rate of heat flow per unit surface area of the insulation divided by the differencebetween the average pipe surface temperat
43、ure and the average air ambient temperature.T r 5 Q2pir2L to 2ta!(4)3.2.4 pipe insulation lineal thermal conductance, CLthe steady-state time rate of heat flow per unit pipe insulation lengthdivided by the difference between the average pipe surface temperature and the average insulation outer surfa
44、ce temperature. Itis the reciprocal of the pipe insulation lineal thermal resistance, RL.CL 5 QLto 2t2!5 1RL(5)3.2.5 pipe insulation lineal thermal resistance, RLthe average temperature difference between the pipe surface and theinsulation outer surface required to produce a steady-state unit time r
45、ate of heat flow per unit of pipe insulation length. It is thereciprocal of the pipe insulation lineal thermal conductance, CL.4 Documents showing details of both guarded-end and calibrated-end apparatus complying with the requirements of this method are available from ASTM for a nominalfee. Order A
46、djunct: ADJC033501 for the Guarded-End Apparatus and Adjunct: ADJC033502 for the Calibrated-End Cap Apparatus.C335/C335M 173RL 5Lto 2t 2!Q 51CL (6)3.2.6 pipe insulation lineal thermal transference, Trpthe steady-state time rate of heat flow per unit pipe insulation lengthdivided by the difference be
47、tween the average pipe surface temperature and the average air ambient temperature. It is a measureof the heat transferred through the insulation to the ambient environment.Trp 5 QLto 2ta!(7)3.2.7 pipe insulation thermal conductivity, pof homogeneous material, the ratio of the steady-state time rate
48、 of heat flow perunit area to the average temperature gradient (temperature difference per unit distance of heat flow path). It includes the effect ofthe fit upon the test pipe and is the reciprocal of the pipe insulation thermal resistivity, rL. For pipe insulation of circular crosssection, the pip
49、e insulation thermal conductivity is: p 5Q 1n r2/r o!L2pito 2t2! 51rL (8)3.2.8 pipe insulation thermal resistivity, rLof homogeneous material, the ratio of the average temperature gradient(temperature difference per unit distance of heat flow path) to the steady-state time rate of heat flow per unit area. It includes theef
