1、Designation: C692 081C692 13Standard Test Method forEvaluating the Influence of Thermal Insulations on ExternalStress Corrosion Cracking Tendency of Austenitic StainlessSteel1This standard is issued under the fixed designation C692; the number immediately following the designation indicates the year
2、 oforiginal adoption or, in the case 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.1 NOTEFig. 4 was editorially corrected in December 2010.1. Scope1.1
3、This test method covers two procedures for the laboratory evaluation of thermal insulation materials to determine whetherthey contribute to external stress corrosion cracking (ESCC) of austenitic stainless steel due to soluble chlorides within theinsulation. This laboratory procedure is not intended
4、 to cover all of the possible field conditions that contribute to ESCC.1.2 While the 1977 edition of this test method (Dana test) is applicable only to wicking-type insulations, the procedures in thisedition are intended to be applicable to all insulating materials, including cements, some of which
5、disintegrate when tested inaccordance with the 1977 edition. Wicking insulations are materials that wet through and through when partially (50 to 75 %)immersed in water for a short period of time (10 min or less).1.3 These procedures are intended primarily as a preproduction test for qualification o
6、f the basic chemical composition of aparticular manufacturers product and are not intended to be routine tests for ongoing quality assurance or production lotcompliance. Test Methods C871, on the other hand, is used for confirmation of acceptable chemical properties of subsequent lotsof insulation p
7、reviously found acceptable by this test method.1.4 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 considered standard.1.5 This standard does not purport t
8、o 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 use.2. Referenced Documents2.1 ASTM Standards:2A240/A240M
9、 Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels andfor General ApplicationsA370 Test Methods and Definitions for Mechanical Testing of Steel ProductsC168 Terminology Relating to Thermal InsulationC795 Specification for Thermal Insulation f
10、or Use in Contact with Austenitic Stainless SteelC871 Test Methods for Chemical Analysis of Thermal Insulation Materials for Leachable Chloride, Fluoride, Silicate, andSodium IonsG30 Practice for Making and Using U-Bend Stress-Corrosion Test Specimens3. Terminology3.1 Definitions: Refer to Terminolo
11、gy C168 for definitions relating to insulation.1 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 Oct. 1, 2008May 1, 2013. Published October 2008M
12、ay 2013. Originally approved in 1971. Last previous edition approved 20062008 asC692 06.C692 081. DOI: 10.1520/C0692-08.10.1520/C0692-13.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume in
13、formation, refer to the standards Document 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
14、 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 Conshohocken, P
15、A 19428-2959. United States14. Summary of Test Method4.1 The procedures in this test method consist of using a specimen of insulation to conduct distilled (or deionized) water bywicking or dripping to an outside surface, through the insulation, to a hot inner surface of stressed Type 304 stainless s
16、teel for aperiod of 28 days. If leachable chlorides are present, they are carried along with the water and concentrated at the hot surface byevaporation in much the same way as has been experienced in actual industrial process situations.4.2 Exposed stainless steel coupons are examined visually, and
17、 under 10 to 30 magnification, if necessary, to detect ESCC afterthe prescribed period of exposure.5. Significance and Use5.1 An inherent characteristic of some alloys of austenitic stainless steel is their tendency to crack at stress points when exposedto certain corrosive environments.The mechanis
18、ms of ESCC are complex and not completely understood but are apparently relatedto certain metallurgical properties. Chloride ions concentrated at a stress point will catalyze crack formation. It has been reportedthat other halide ions do not promote ESCC to the same degree as does chloride using the
19、 test technology of Test Method andfluoride ions have the potential to induce stress corrosion cracking in the absence of inhibiting ions.C692 (drip test).35.2 Chlorides are common to many environments, so great care shall be taken to protect austenitic stainless steel from chloridecontamination.5.3
20、 Most thermal insulations will not, of themselves, cause stress corrosion cracking as shown by qualification tests. Whenexposed to elevated-temperature (boiling point range), environments containing chlorides, moisture, and oxygen, however, someinsulation systems cracking. Preproduction qualificatio
21、n tests are used to evaluate that under the conditions of the laboratory testthat specific thermal insulation materials do not cause cracking of sensitized austenitic stainless steel. Insulation systems have thepotential to act as collecting media, transmigrating and concentrating chlorides media by
22、 means of transmigration andconcentration of corrosive ions on heated stainless steel surfaces. If moisture is not present, the chloride salts cannot migrate, andstress corrosion cracking because of chloride-contaminated insulation cannot take place.Exposure to elevated temperature resultsin evapora
23、tion of water and increased chemical reaction rates. Environments containing corrosive ions, moisture, and oxygen willincrease the chance for stress corrosion cracking.5.4 Insulation materials are available that are specially formulated to inhibit stress corrosion cracking in the presence ofchloride
24、s through modifications in basic composition or incorporation of certain chemical additives.5.5 The ability of the 28-day test to measure the corrosion potential of insulation materials is documented by Karnes,4 whosedata appear to have been used for construction of the acceptability curve used in S
25、pecification C795 and other specifications.5.6 The metal for all of the coupons used in this test method (C692) shall be qualified (see Section 14) to ascertain that underconditions of the test, chloride ions will cause the metal to crack, and deionized water alone will not cause cracks.6. Applicabi
26、lity (see also 11.2)6.1 While the original test procedure for the 1977 edition of this test method (Dana Test) was limited to “wicking-typeinsulations,” the “drip test procedure” given in this edition is applicable to all insulations when cut or formed into the required testspecimen.6.2 Heat treatme
27、nt at some temperature (as recommended by the manufacturer) up to the maximum use temperature issometimes necessary to make the insulating material “wick,” and thus testable by either insulation test procedure (see Sections 12and 13).6.3 If the test insulation cannot be made to wick in any way (such
28、 as in the case of organic or inorganic closed-cell foams), orwhen heat treatment of a component of the insulation (such as an attached exterior jacket material) exceeds the manufacturersrecommended maximum temperature for the exterior component, then the 112-in. (38-mm) wide test specimen is sliced
29、 into two34-in. (19-mm) thick segments. The two halves are held together with wire, pins, or a rubber band, and are tested by dripping intothe crack between the two halves, thus simulating the situation where water penetrates the junction between two sections ofinsulation. Wetting the mating faces o
30、n the two half sections facilitates water wicking down to the coupon surface.6.4 Adhesives are tested by gluing together a test block of the insulation material to be used with the adhesive. The adhesivejoint must come into contact with the stainless steel test coupon.6.5 Cements with a clay binder
31、are tested by casting a 112-in. (38-mm) thick slab, drying, and using the drip procedure. Sucha sample will disintegrate in the Dana test procedure.3 Private communication from authors of paper presented at Bal Harbour ASTM C16 Symposium on December 9, 1987. Whitaker, T. E., Whorlow, K. M., and Hutt
32、o, F.B., Jr., “New Developments in Test Technology for ASTM C692.” Whorlow, Kenneth M., Woolridge, Edward and Hutto, Francis B., Jr., “Effect of Halogens and Inhibitorson the External Stress Corrosion Cracking of Type 304Austenitic Stainless Steel”; STP 1320 Insulation Materials: Testing and Applica
33、tions, Third Volume, Ronald S. Gravesand Robert R. Zarr, editors , ASTM West Conshohocken, PA, 1997 page 4854 Karnes, H. F., “The Corrosion Potential of Wetted Thermal Insulation,” AICHE, 57th National Meeting, Minneapolis, MN, September 26 through 29, 1965.C692 1326.6 The drip procedure has the pot
34、ential to be used for the testing of coatings applied to the coupon prior to test. The corrosiveliquids dripped into such a system are limited only by the imagination of the researcher.7. Apparatus for Dana Test Procedure7.1 EnclosureIn dusty environments, it is permissible for the test apparatus to
35、 be located in a cabinet or other closed structureprovided with a blower to maintain a positive internal pressure, and equipped with a filter for intake air to minimize dust or othercontamination. The test apparatus is normally housed in any suitable clean environment not subject to chloride contami
36、nation. Theenclosure shall not be so tight as to exclude oxygen from the system, since oxygen is necessary for ESCC to occur.7.2 Pyrex Glass Wool.7.3 “Cookie Cutter,” made from 114 in. (32 mm) thin wall electrical conduit (inside diameter 1.38 in. (35 mm) to cut a 138-in.(35-mm) diameter plug from 2
37、-in. (51-mm) Pyrex Glass Wool.7.4 Specimen Holder, as shown in Fig. 1, or equivalent.7.5 Precision Bender, see Practice G30.7.6 Wet-Grinding Belt Grinder, 80-grit.7.7 Copper Lugs, commercial 2/04/0 solderless, or 2 by 12 by 18 in. (51 by 13 by 3.2 mm) copper tabs.7.8 Silver Solder, and chloride-free
38、 flux for use with stainless steel.7.9 Torch, acetylene or propane.7.10 Bolt, stainless steel, 316 in. (5 mm) in diameter and 212-in. (65-mm) long with insulating washer and nut for electricallyinsulating the bolt from the U-bend specimen.7.11 Hand-Held Magnifier, 10 or 30 binocular microscope, or b
39、oth.7.12 Band Saw.7.13 Hole Saw, 2-in. (51-mm) outside diameter (optional).7.14 Crystallizing Dish, of borosilicate glass, 712 in. (190 mm) in diameter by 4 in. (100 mm) in depth, or stainless steel pan912 by 512 by 4 in. (41 by 140 by 102 mm) deep.7.15 Electrical Transformer, isolation-type. (appro
40、ximately 150 mV/150 AMP).7.16 Thermocouple, 28 gage or smaller.7.17 Epoxy Adhesive, aluminum filled.7.18 Drill Bit, 932-in. (7-mm), cobalt steel preferred.7.19 Dye Penetrant and Developer, available at most welding supply houses.8. Apparatus for Drip Test Procedure8.1 Steam Heated PipeA5-ft (1.5-m)
41、section of 112 in. IPS pipe (inconel or other corrosion-resistant material), is heated eitherby a small self-contained steam boiler or by regulated house steam.8.2 Peristaltic PumpA multichannel peristaltic pump is used to supply 250 (625) mL/day to each specimen.8.3 I.V. Bottles, 1 L or equivalent,
42、 to individually supply each test specimen with test liquid.8.4 Specimen Holder, for grinding. See Fig. 1.8.5 Precision Bender, see Fig. 2 in the 1979 edition of Practice G30.8.6 Wet-Sanding Belt Sander, with 80-grit belt.FIG. 1 Suction Cup Coupon HolderC692 1338.7 Bolt, stainless steel, 316 in. (5
43、mm) in diameter by 212-in. (65-mm) long with nut.8.8 Hole Saw, 2-in. (51-mm) outside diameter.8.9 Band Saw.8.10 Thermocouple, 28 gage or smaller.8.11 Heat Transfer Grease, chloride free.8.12 Kimwipe Tissue,5 chloride free.9. Reagents and Materials9.1 Distilled or Deionized Water, containing less tha
44、n 0.1 ppm chloride ions.9.2 Distilled or Deionized Water, containing 1500 ppm chloride ion (2.473 g NaCl/L).9.3 Type 304 Stainless Steel Sheet16 gage, meeting the composition requirements of Specification A240/A240M. Certificatesof chemical composition and mechanical properties, including ultimate t
45、ensile strength and yield strength by the 0.2 % offsetmethod are required. Type 304 stainless steel meeting Specification A240/A240M shall have a carbon content in the range of0.050.06 % and shall be solution-annealed.10. Test Coupons10.1 Shear 2 by 7-in. (51 by 178-mm) coupons from 16-gage Type 304
46、 stainless sheet, as specified in 9.3, with the longdimension parallel to the long dimension of the sheet. (Long dimension parallel to sheet-rolling direction.)10.2 Clean coupons with chloride-free liquid soap and water to remove any grease or other contamination.10.3 Sensitize all coupons before be
47、nding by heating at 1200F (649C) in an argon (inert) or air (oxidizing) atmosphere forthree hours. Let cool in the furnace after the sensitizing period.6 Temperature of the coupons must be measured in the stack ofcoupons, not in the furnace itself, as the coupon temperatures “lag” the furnace temper
48、ature by at least 50 to 100F (28 to 56C).10.4 A suggestion for sensitizing in an inert atmosphere is to use a stainless steel box with a tight-fitting cover to contain theargon around the coupons during sensitization.10.5 Grip coupon with suction cup holder (see Fig. 1) or other means to facilitate
49、wet grinding on an 80-grit belt grinder. Grindparallel to the long dimension of the coupon using an 80-grit wet belt with just enough pressure to remove the dull finish and leavethe metal bright. Do not overgrind. The beltground face is the test surface to be exposed to the thermal insulation. The test areais the bent coupon surface that actually comes into contact with the insulation.10.6 Smooth and round sheared edges to prevent accidental cutting of fingers.10.7 Bend each ground coupon to a 1.00 6 0.01-in. (25.4 6 0.25-mm) outside radius
