1、Designation: C356 10C356 17Standard Test Method forLinear Shrinkage of Preformed High-Temperature ThermalInsulation Subjected to Soaking Heat1This standard is issued under the fixed designation C356; the number immediately following the designation indicates the year oforiginal adoption or, in the c
2、ase of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript 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. Scope1.1 Thi
3、s test method covers the determination of the amount of linear shrinkage and other changes that occur when a preformedthermal insulating material is exposed to soaking heat. This test method is limited to preformed high-temperature insulation thatis applicable to hot-side temperatures in excess of 2
4、00F (93C),150F (66C), with the exception of insulating fire brick whichis covered by Test Method C210.1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information only and are not c
5、onsidered standard.1.3 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 establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to us
6、e.1.4 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to
7、Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2C168 Terminology Relating to Thermal InsulationC210 Test Method for Reheat Change of Insulating FirebrickC411 Test Method for Hot-Surface Performance of High-Temperature Thermal Insulation3. Terminology3.1 DefinitionsTerminology C168 s
8、hall apply to the terms used in this test method.4. Significance and Use4.1 Linear shrinkage, as used in this test method, refers to the change in linear dimensions that has occurred in test specimensafter they have been subjected to soaking heat for a period of 24 h and then cooled to room temperat
9、ure.4.2 Most insulating materials will begin to shrink at some definite temperature. Usually the amount of shrinkage increases asthe temperature of exposure becomes higher. Eventually a temperature will be reached at which the shrinkage becomes excessive.With excessive shrinkage, the insulating mate
10、rial has definitely exceeded its useful temperature limit. When an insulating materialis applied to a hot surface, the shrinkage will be greatest on the hot face. The differential shrinkage which results between the hotterand the cooler surfaces often introduces strains and may cause the insulation
11、to warp. High shrinkage may cause excessive warpageand thereby may induce cracking, both of which are undesirable. High shrinkage may also open gaps at the insulation joints toan excessive extent rendering the application less efficient and more hazardous. In order to predict the limit of permissibl
12、e1 This test method is under the jurisdiction of ASTM Committee C16 on Thermal Insulation and is the direct responsibility of Subcommittee C16.31 on Chemical andPhysical Properties.Current edition approved Sept. 1, 2010May 1, 2017. Published September 2010June 2017. Originally approved in 1960. Last
13、 previous edition approved in 20032010 asC356C356 10. 03. DOI: 10.1520/C0356-10.10.1520/C0356-17.2 For referencedASTM 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 Docume
14、nt Summary page on the ASTM website.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 possible to adequately depict all changes accurately, ASTM rec
15、ommends 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 Conshohocken, PA 19428-2959. United States1shrinkage in
16、 service, the degree of linear shrinkage to be tolerated by specimens of an insulating material when subjected tosoaking heat must be determined from experience.4.3 It is recognized that a fixed relation between linear shrinkage under soaking heat and actual shrinkage in service cannot beestablished
17、 for different types of insulating materials. Generally the amount of shrinkage increases with time of exposure. Theamount and rate of increase varies from one material to another. In addition, the various types of materials may have differentamounts of maximum permissible shrinkage. Therefore, each
18、 product must define its own specific limits of linear shrinkage undersoaking heat.5. Apparatus5.1 FurnaceA gas-fired or electrically heated muffle furnace, having a size sufficient to accommodate at least four testspecimens and two dummy specimens, 6 by 212 by 112 in. (152.4 by 63.5 by 38.1 mm) (No
19、te 1), spaced so as to allow a clearanceof at least 12 in. (12.7 mm) on all surfaces of every test specimen. The temperature of the furnace shall be controlled throughoutthe volume occupied by the specimens to within 6 1 % of the desired temperature. A furnace-temperature indicator or recorderis req
20、uired.NOTE 1If the structure is not homogeneous throughout its thickness, or if thinner materials are under test, then test the specimen should be testedwithout altering at the original thickness. For smaller ovens, unable to accommodate the required number of specimens, it will be necessary to make
21、several test batches in order to secure the minimum number of specimens required.5.2 OvenA controlled-temperature conditioning oven with range up to at least 250F (121C).5.3 Specimen-Measuring ApparatusAn instrument suitable for measuring a gauge length up to 6 in. (152.4 mm), and havingan accuracy
22、of measurement of 0.002 in. (0.05 mm) or better. Care must be taken, by the use of proper measuring techniques, toensure reproduction of any measurement to within 0.01 in. (0.2 mm). It is particularly important to avoid crushing the ends of thespecimens during measurement, especially in the case of
23、soft materials.NOTE 2Reference points, such as pins, inserted near the ends of the specimen, serve to improve reproducibility without specimen damage; or it isacceptable to insert metal strips may be inserted between the specimen ends and the jaws of the caliper. Suggested instruments are dilatomete
24、rs, verniercaliper, or comparators. One suitable type of comparator is equipped with a fine adjustment. It has a long-range, continuous dial indicator. The dial isattached to a wide-face (12-in. (12.7-mm) diameter flat) button point which is held against the specimen by internal spring pressure. Whe
25、n the point islifted 12 in. (12.7 mm), the pressure is about 50 g, corresponding to a bearing force of 0.6 psi (4.8 kPa), and suitable for very soft materials. For hardermaterials, an additional weight of 0.25 lb (0.114 kg) may be applied, making the load of the specimen, at 12 in. (12.7 mm) compres
26、sion of the spring,about 1.9 psi (13.1 kPa). Directly beneath the button point is another wide-face button point tapped to the base of the comparator. The comparator isadjustable and requires a set of steel shaftings, 12 in. (12.7 mm) in diameter, having lengths at 1-in. (25.4-mm) intervals from 1 t
27、o 6 in. (25.4 to 152.4mm), to zero the comparator accurately.5.4 BalanceA balance, having an accuracy of 0.01 g, for weighing the specimen before and after heating.6. Sampling and Preparation of Test Specimens6.1 All samples that will be required to complete the tests shall be selected at one time a
28、nd in such a manner as to berepresentative of the average of the material.6.2 Specimens for any one test condition shall be selected from the original sample lot so as to be as representative as possible.The specimens shall be cut or sawed from full-size pieces in such a manner that they will be ful
29、ly representative of the entire,full-size piece as well as of the material generally. These specimens shall be cut to size 6 by 212 by 112 in. (152.4 by 63.5 by 38.1mm), in such a mannnermanner that the length and width are cut parallel to the length and width, respectively, of the original,full-siz
30、e piece. If it is impossible to faithfully represent the material by cutting to a 112-in. (38.1-mm) thick specimen, or for thinnerpieces, then the original thickness of the material shouldshall be tested. Rectangular specimens cut from pipe covering mayshallbe used if the material is homogeneous and
31、 if the sections are large enough. If the material is not homogeneous or the sectionsare not sufficiently large, then curved or partly curved segments of a cylinder mayshall be used. In this case, the specimens shallpreferably be cut to an over-all width of 212 in. (63.5 mm), with the sides cut para
32、llel rather than on a radius.7. Procedure7.1 Select and prepare a minimum of four test specimens as prescribed in Section 6. Weigh the specimens in the as-receivedcondition and dry them to constant weight following applicable specifications for the material unless it has been shown that thedimension
33、al stability is not significantly affected by moisture content. In the absence of such specifications, dry the specimen inan oven or desiccator at a temperature of 215 to 250F (102 to 121C) or at a suitable lower temperature if these temperatureswould be destructive. If specimens are dried, alloweal
34、low specimens to cool to room temperature and if necessary held in adesiccator before testing. Other conditioning procedures are acceptable only where agreed upon between manufacturer andpurchaser. After conditioning and before any changes in dimensions occur, determine the linear dimensions. Make a
35、t least onemeasurement of length and two each of width and thickness at points marked so that remeasurements can be made at the samepoints after soaking heat.7.2 Place the measured and weighed specimens in the furnace, the temperature of which shall not exceed 250F (121C). Thespecimens shall rest on
36、 their 6 by 112-in. (152.4 by 38.1-mm) edges, supported by at least three supports (such as small ceramicC356 172triangular bars, or cylindrical rods), which in turn shall be supported on a protective plate. The supporting bars or rods shall belarge enough so that the specimens have a clearance of a
37、t least 12 in. (12.7 mm) above the protecting plate.Arrange the specimensface to face in a group, but separated at least 12 in. (12.7 mm) from each other. Place dummy blocks or other protective meansalong the sides of the two specimens at each end of the group, so as to protect the faces of these tw
38、o specimens from radiationlosses or gains from the inner surfaces of the furnace. This arrangement of the specimens will allow free access of the heat to allof their surfaces.7.3 Apply the source of heat after the specimens have been arranged in the furnace. The rate of heat supply shall be controll
39、edso that the average rise to the temperature of test shall not exceed 300F (167C)/h (Notes 3 and 4). During the heating-up period,especially in the initial stages, make frequent observations to note any signs of combustibility, by opening the furnace doormomentarily or, if possible, through observa
40、tion ports. After the furnace has reached the desired test temperature, maintainsoaking-heat conditions for a period of 24 h, and then cut off the supply of heat. When the furnace has cooled to 200 to 250F(93 to 121C), remove the specimens and place them directly into a desiccator.NOTE 3It is realiz
41、ed that the actual rate of increase in temperature will not be uniform. The temperature will rise rapidly at first, and then will continueto rise progressively slower as the final temperature is approached. By the statement, “the average rise in temperature shall not exceed 300F (167C)/h,”it is mean
42、t, for example, that a final temperature of 600F (316C) needs to be reached in not less than 2 h, or in not less than 6 h if the test temperatureis to be 1800F (982C).NOTE 4 If it is desired to determine the ability of an insulation to withstand sudden, drastic changes in temperature, or thermal sho
43、ck, a separate testfor this condition shall be specified.7.4 When the specimens have cooled to within 10F (5.5C) of room temperature, remove them from the desiccator andremeasure before any changes can occur. Weigh the specimens and measure their dimensions at the exact points which were usedfor det
44、ermining the original lengths (see 7.1). If any warpage occurred during the soaking heat, determine the amount of warpageto the nearest 0.01 in. (0.2 mm) in accordance with Test Method C411. If the warpage exceeds 0.04 in. (1.0 mm), the actual lengthof the specimen as such shall not be determined. I
45、nstead, determine the apparent length of the specimen by measuring the chordconnecting the two edges of the concave surface of the warped specimen, or by measuring the chord connecting the two pointsof original measurement.7.5 Examine the specimens, and note any visible changes that have occurred du
46、ring the heating.8. Calculations8.1 Linear ShrinkageCalculate the percentage linear dimensional change after soaking heat as follows:S 5L12L2!/L1#3100 (1)where:S = percentage linear dimensional change upon soaking heat,L1 = average length, width, or thickness of specimen before soaking heat, in. (or
47、 mm), andL2 = average length, width, or thickness of specimen after soaking heat, in. (or mm).8.2 Apparent Linear ShrinkageCalculate the percentage apparent dimensional change after soaking heat when a specimen haswarped excessively (more than 0.04 in. (1.0 mm) by the same formula as for linear shri
48、nkage, except that L2 shall represent theapparent length of the specimen after soaking heat.8.3 Change in WeightCalculate the percent change in weight after soaking heat as follows:C 5W12W2!/W1#3100 (2)where:C = percentage change in weight after soaking heat,W1 = weight of specimen before soaking he
49、at, g, andW2 = weight of specimen after soaking heat, g.9. Report9.1 Report the following information:9.1.1 Conditioning procedure followed,9.1.2 Temperature of test, the time to reach temperature, the time at temperature, and the time for the temperature to drop 100F(55.5C) after the heat is turned off,9.1.3 Linear shrinkage,shrinkage in length, width, and thickness,9.1.4 Warpage, if any,9.1.5 Apparent linear shrinkage, if the warpage is in excess of 0.04 in. (1 mm),9.1.6 Change in weight,9.1.7 Any visible changes in the mat
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