1、Designation: C692 081Standard 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 oforig
2、inal 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.1NOTEFig. 4 was editorially corrected in December 2010.1. Scope1.1 This tes
3、t method covers two procedures for the labora-tory evaluation of thermal insulation materials to determinewhether they contribute to external stress corrosion cracking(ESCC) of austenitic stainless steel due to soluble chlorideswithin the insulation. This laboratory procedure is not intendedto cover
4、 all of the possible field conditions that contribute toESCC.1.2 While the 1977 edition of this test method (Dana test) isapplicable only to wicking-type insulations, the procedures inthis edition are intended to be applicable to all insulatingmaterials, including cements, some of which disintegrate
5、 whentested in accordance with the 1977 edition. Wicking insulationsare materials that wet through and through when partially (50to 75 %) immersed in water for a short period of time (10 minor less).1.3 These procedures are intended primarily as a preproduc-tion test for qualification of the basic c
6、hemical composition ofa particular manufacturers product and are not intended to beroutine tests for ongoing quality assurance or production lotcompliance. Test Methods C871, on the other hand, is used forconfirmation of acceptable chemical properties of subsequentlots of insulation previously found
7、 acceptable by this testmethod.1.4 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.5 This standard does not purport to address all of t
8、hesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2A240/A240M Specification f
9、or Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for PressureVessels and for General ApplicationsA370 Test Methods and Definitions for Mechanical Testingof Steel ProductsC168 Terminology Relating to Thermal InsulationC795 Specification for Thermal Insulation for Use in Con-tac
10、t with Austenitic Stainless SteelC871 Test Methods for Chemical Analysis of ThermalInsulation Materials for Leachable Chloride, Fluoride,Silicate, and Sodium IonsG30 Practice for Making and Using U-Bend Stress-Corrosion Test Specimens3. Terminology3.1 Definitions:Refer to Terminology C168 for defini
11、tions relating to insu-lation.4. Summary of Test Method4.1 The procedures in this test method consist of using aspecimen of insulation to conduct distilled (or deionized) waterby wicking or dripping to an outside surface, through theinsulation, to a hot inner surface of stressed Type 304 stainlessst
12、eel for a period of 28 days. If leachable chlorides are present,they are carried along with the water and concentrated at thehot surface by evaporation in much the same way as has beenexperienced in actual industrial process situations.1This test method is under the jurisdiction ofASTM Committee C16
13、 on ThermalInsulation and is the direct responsibility of Subcommittee C16.31 on Chemical andPhysical Properties.Current edition approved Oct. 1, 2008. Published October 2008. Originallyapproved in 1971. Last previous edition approved 2006 as C692 06. DOI:10.1520/C0692-08.2For referenced ASTM standa
14、rds, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA
15、 19428-2959, United States.4.2 Exposed stainless steel coupons are examined visually,and under 10 to 303 magnification, if necessary, to detectESCC after the prescribed period of exposure.5. Significance and Use5.1 An inherent characteristic of some alloys of austeniticstainless steel is their tende
16、ncy to crack at stress points whenexposed to certain corrosive environments. The mechanisms ofESCC are complex and not completely understood but areapparently related to certain metallurgical properties. Chlorideions concentrated at a stress point will catalyze crack forma-tion. It has been reported
17、 that other halide ions do not promoteESCC to the same degree as does chloride using the testtechnology of Test Method C692 (drip test).35.2 Chlorides are common to many environments, so greatcare shall be taken to protect austenitic stainless steel fromchloride contamination.5.3 Most thermal insula
18、tions will not, of themselves, causestress corrosion cracking as shown by qualification tests. Whenexposed to elevated-temperature (boiling point range), envi-ronments containing chlorides, moisture, and oxygen, how-ever, some insulation systems act as collecting media, trans-migrating and concentra
19、ting chlorides on heated stainless steelsurfaces. If moisture is not present, the chloride salts cannotmigrate, and stress corrosion cracking because of chloride-contaminated insulation cannot take place.5.4 Insulation materials are available that are speciallyformulated to inhibit stress corrosion
20、cracking in the presenceof chlorides through modifications in basic composition orincorporation of certain chemical additives.5.5 The ability of the 28-day test to measure the corrosionpotential of insulation materials is documented by Karnes,4whose data appear to have been used for construction of
21、theacceptability curve used in Specification C795 and otherspecifications.5.6 The metal for all of the coupons used in this test method(C692) shall be qualified (see Section 14) to ascertain thatunder conditions of the test, chloride ions will cause the metalto crack, and deionized water alone will
22、not cause cracks.6. Applicability (see also 11.2)6.1 While the original test procedure for the 1977 edition ofthis test method (Dana Test) was limited to “wicking-typeinsulations,” the “drip test procedure” given in this edition isapplicable to all insulations when cut or formed into therequired tes
23、t specimen.6.2 Heat treatment at some temperature (as recommendedby the manufacturer) up to the maximum use temperature issometimes necessary to make the insulating material “wick,”and thus testable by either insulation test procedure (seeSections 12 and 13).6.3 If the test insulation cannot be made
24、 to wick in any way(such as in the case of organic or inorganic closed-cell foams),or when heat treatment of a component of the insulation (suchas an attached exterior jacket material) exceeds the manufac-turers recommended maximum temperature for the exteriorcomponent, then the 112-in. (38-mm) wide
25、 test specimen issliced into two34-in. (19-mm) thick segments. The two halvesare held together with wire, pins, or a rubber band, and aretested by dripping into the crack between the two halves, thussimulating the situation where water penetrates the junctionbetween two sections of insulation. Wetti
26、ng the mating faceson the two half sections facilitates water wicking down to thecoupon surface.6.4 Adhesives are tested by gluing together a test block ofthe insulation material to be used with the adhesive. Theadhesive joint must come into contact with the stainless steeltest coupon.6.5 Cements wi
27、th a clay binder are tested by casting a112-in. (38-mm) thick slab, drying, and using the drip proce-dure. Such a sample will disintegrate in the Dana test proce-dure.6.6 The drip procedure has the potential to be used for thetesting of coatings applied to the coupon prior to test. Thecorrosive liqu
28、ids dripped into such a system are limited only bythe imagination of the researcher.7. Apparatus for Dana Test Procedure7.1 EnclosureIn dusty environments, it is permissible forthe test apparatus to be located in a cabinet or other closedstructure provided with a blower to maintain a positive intern
29、alpressure, and equipped with a filter for intake air to minimizedust or other contamination. The test apparatus is normallyhoused in any suitable clean environment not subject tochloride contamination. The enclosure shall not be so tight asto exclude oxygen from the system, since oxygen is necessar
30、yfor ESCC to occur.7.2 Pyrex Glass Wool.7.3 “Cookie Cutter,” made from 114 in. (32 mm) thin wallelectrical conduit (inside diameter 1.38 in. (35 mm) to cut a138-in. (35-mm) diameter plug from 2-in. (51-mm) PyrexGlass Wool.7.4 Specimen Holder, as shown in Fig. 1, or equivalent.7.5 Precision Bender, s
31、ee Practice G30.7.6 Wet-Grinding Belt Grinder, 80-grit.7.7 Copper Lugs, commercial 2/04/0 solderless, or 2 by12by18 in. (51 by 13 by 3.2 mm) copper tabs.7.8 Silver Solder, and chloride-free flux for use with stain-less steel.3Private communication from authors of paper presented at Bal Harbour ASTMC
32、16 Symposium on December 9, 1987. Whitaker, T. E., Whorlow, K. M., and Hutto,F. B., Jr., “New Developments in Test Technology for ASTM C692.”4Karnes, H. F., “The Corrosion Potential ofWettedThermal Insulation,”AICHE,57th National Meeting, Minneapolis, MN, September 26 through 29, 1965. FIG. 1 Suctio
33、n Cup Coupon HolderC692 08127.9 Torch, acetylene or propane.7.10 Bolt, stainless steel,316 in. (5 mm) in diameter and212-in. (65-mm) long with insulating washer and nut forelectrically insulating the bolt from the U-bend specimen.7.11 Hand-Held Magnifier,103 or 303 binocular micro-scope, or both.7.1
34、2 Band Saw.7.13 Hole Saw, 2-in. (51-mm) outside diameter (optional).7.14 Crystallizing Dish, of borosilicate glass, 712 in. (190mm) in diameter by 4 in. (100 mm) in depth, or stainless steelpan 912 by 512 by 4 in. (41 by 140 by 102 mm) deep.7.15 Electrical Transformer, isolation-type. (approximately
35、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 weld-ing supply houses.8. Apparatus for Drip Test Procedure8.1 Steam Heated PipeA 5-ft (1.5-m) section
36、of 112 in.IPS pipe (inconel or other corrosion-resistant material), isheated either by a small self-contained steam boiler or byregulated house steam.8.2 Peristaltic PumpA multichannel peristaltic pump isused to supply 250 (625) mL/day to each specimen.8.3 I.V. Bottles, 1 L or equivalent, to individ
37、ually supplyeach 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 ofPractice G30.8.6 Wet-Sanding Belt Sander, with 80-grit belt.8.7 Bolt, stainless steel,316 in. (5 mm) in diameter by212-in. (65-mm) long with nut.8.8 Ho
38、le 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,5chloride free.9. Reagents and Materials9.1 Distilled or Deionized Water, containing less than 0.1ppm chloride ions.9.2 Distilled or Deionized Water,
39、 containing 1500 ppmchloride ion (2.473 g NaCl/L).9.3 Type 304 Stainless Steel Sheet16 gage, meeting thecomposition requirements of Specification A240/A240M. Cer-tificates of chemical composition and mechanical properties,including ultimate tensile strength and yield strength by the0.2 % offset meth
40、od are required. Type 304 stainless steelmeeting Specification A240/A240M shall have a carbon con-tent in the range of 0.050.06 % and shall be solution-annealed.10. Test Coupons10.1 Shear 2 by 7-in. (51 by 178-mm) coupons from16-gage Type 304 stainless sheet, as specified in 9.3, with thelong dimens
41、ion 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 waterto remove any grease or other contamination.10.3 Sensitize all coupons before bending by heating at1200F (649C) in an argon (inert) or air (
42、oxidizing) atmo-sphere for three hours. Let cool in the furnace after thesensitizing period.6Temperature of the coupons must bemeasured in the stack of coupons, not in the furnace itself, asthe coupon temperatures “lag” the furnace temperature by atleast 50 to 100F (28 to 56C).10.4 Asuggestion for s
43、ensitizing in an inert atmosphere is touse 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)orother means to facilitate wet grinding on an 80-grit belt grinder.Grind parallel to the long
44、dimension of the coupon using an80-grit wet belt with just enough pressure to remove the dullfinish and leave the metal bright. Do not overgrind. Thebeltground face is the test surface to be exposed to the thermalinsulation. The test area is the bent coupon surface that actuallycomes into contact wi
45、th the insulation.10.6 Smooth and round sheared edges to prevent accidentalcutting of fingers.10.7 Bend each ground coupon to a 1.00 6 0.01-in. (25.4 60.25-mm) outside radius using a roll bender as shown in Fig. 5of the 1979 edition of Practice G30 to produce a U-shape inwhich the “legs” are paralle
46、l to within116 in. (1.6 mm).10.8 Drill or punch a932-in. (7-mm) hole in each end usingthe special jig shown in Fig. 3. Cobalt steel drill bits are usedon 304 stainless steel as other bits dull quickly.10.9 For the Dana test only, silver-solder a 2/04/0 solder-less copper electrical connector to each
47、 leg with the hole in theconnector centered on the drilled hole. While it has been5Kimwipe is a trademarked product of Kimberly-Clark Corp., Roswell, GA.6For a discussion of the effect of sensitizing stainless steel and its susceptibilityto stress corrosion, refer to “Stress-Corrosion Cracking of Se
48、nsitized Stainless Steelin Oxygenated High Temperature Water,” Batelle Columbus Laboratories, ReportNo. BMI 1927, June 1972.FIG. 2 Typical External Stress Corrosion Cracks (53Magnification)C692 0813conventional to solder one lug to an inside surface and thesecond to an outside surface, it is accepta
49、ble to solder both tooutside surfaces for greater convenience. The body of thecoupon is shielded from high soldering temperatures byplacing a soaking-wet chloride-free cellulose pad on thecoupon next to the weld area to act as a heat sink. Carefullyremove all flux from the finished coupon by washing with hotwater. The contact surfaces of the copper connector is cleanedby sanding, wire brush, or other means to avoid electricalcontact problems.10.9.1 As an alternate to the 2/04/0 solderless lug, 2 by12by18-in. (50.8 by 13 by 3.2-mm) copper lug
