1、Designation: D 807 05Standard Practice forAssessing the Tendency of Industrial Boiler Waters toCause Embrittlement (USBM1Embrittlement DetectorMethod)2This standard is issued under the fixed designation D 807; the number immediately following the designation indicates the year oforiginal adoption or
2、, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice,3known as the embrittlement-detectormethod, covers the apparatus
3、 and procedure for determiningthe embrittling or nonembrittling characteristics of the water inan operating boiler. The interpretation of the results shall berestricted to the limits set forth in Section 8.6.NOTE 1The embrittlement detector was designed to reproduce closelythe conditions existing in
4、 an actual boiler seam. It is considered probablethat the individual conditions of leakage, concentration, and stress in theboiler seam can equal those in the detector. The essential differencebetween the detector and the boiler is that the former is so constructed andoperated that these three major
5、 factors act simultaneously, continuously,and under the most favorable circumstances to produce cracking; whereas,in the boiler the three factors are brought together only under uniquecircumstances. Furthermore, in the detector any cracking is produced in asmall test surface that can be inspected th
6、oroughly, while the susceptibleareas in a boiler are large and can be inspected only with difficulty. Inthese respects the embrittlement detector provides an accelerated test ofthe fourth condition necessary for embrittlement, the embrittling nature ofthe boiler water.NOTE 2Cracks in a specimen afte
7、r being subjected to this test indicatethat the boiler water can cause embrittlement cracking, but not that theboiler in question necessarily has cracked or will crack.1.2 The effectiveness of treatment to prevent cracking, aswell as an indication of whether an unsafe condition exists, areshown by t
8、his practice. Such treatments are evaluated in termsof method specimen resistance to failure.1.3 The practice may be applied to embrittlement resistancetesting of steels other than boiler plate, provided that aduplicate, unexposed specimen does not crack when bent 90on a 2-in. (51-mm) radius.1.4 Thi
9、s standard does not purport to address all of thesafety 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 Document
10、s2.1 ASTM Standards:4A 108 Specification for Steel Bars, Carbon, Cold-FinishedA 515/A 515M Specification for Pressure Vessel Plates,Carbon Steel, for Intermediate- and Higher-TemperatureServiceD 1129 Terminology Relating to WaterD 1193 Specification for Reagent WaterE3 Practice for Preparation of Me
11、tallographic SpecimensE 883 Guide for Reflected-Light PhotomicrographyE 1351 Practice for Production and Evaluation of FieldMetallographic Replicas3. Terminology3.1 Definitions:3.1.1 The term embrittlement cracking in this test method isdefined in accordance with Terminology D 1129 as follows:3.1.1.
12、1 embrittlement crackinga form of metal failure thatoccurs in steam boilers at riveted joints and at tube ends, thecracking being predominantly intercrystalline.NOTE 3This form of cracking, which has been known as “causticembrittlement,” is believed to result from the action of certain constituentso
13、f concentrated boiler water upon steel under stress.1United States Bureau of Mines.2This test method is under the jurisdiction of ASTM Committee D19 on Waterand is the direct responsibility of Subcommittee D19.03 on Sampling of Water andWater-Formed Deposits, Analysis of Water for Power Generation a
14、nd Process Use,On-Line Water Analysis, and Surveillance of Water.Current edition approved Nov. 1, 2005. Published November 2005. Originallyapproved in 1944. Last previous edition approved in 2000 as D 807 00.3This test method was developed during an investigation conducted under acooperative agreeme
15、nt between the Joint Research Committee on Boiler FeedwaterStudies and the United States Bureau of Mines.For information on the development of this test method reference may be madeto the following:Schroeder, W. C. and Berk, A. A. “Intercrystalline Cracking of Boiler Steel andIts Prevention,” Bullet
16、in 443, U.S. Bureau of Mines, 1941.Schroeder, W. C., Berk, A. A. and Stoddard, C. K. “Embrittlement DetectorTesting on Boilers,” Power Plant Engineering, Vol 45, August, 1941, pp. 6976.“Embrittlement Symposium,” Transactions of the Am. Soc. Mech. Engrs., Vol64, 1942, pp. 393444.Whirl, S. F. and Purc
17、ell, T. E. “Protection Against Caustic Embrittlement byCoordinated Phosphate-pH Control,” Proceedings, Third Annual Water Conference,Engrs. Soc. of Western Penna., 1942, pp. 4560.Berk, A. A. and Schroeder, W. C. “A Practical Way to Prevent EmbrittlementCracking,” Transactions, Am. Soc. Mech. Engr.,
18、Vol 65, 1943, pp. 701711.4For referenced ASTM standards, 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 B
19、arr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.NOTE 4For a detailed discussion as to what cracking should beconsidered significant for the purpose of this practice, see Section 8.6.3.1.2 For definitions of other terms used in this practice,refer to Terminology D 1129.
20、4. Summary of Practice4.1 For embrittlement cracking of the boiler metal to bepossible, the boiler water must concentrate a thousand times ormore in contact with the metal under high residual or appliedtensile stress. In a boiler such concentration may take place inriveted seams or in annular spaces
21、 at tube ends, and the steel atsuch locations may be highly stressed when the boiler isconstructed or may become highly stressed when it is operated.If the chemicals in the boiler water concentrate in the seams todevelop an embrittling solution, cracking may occur.4.2 In the embrittlement detector (
22、Fig. 1), the conditions ofconcentration and stress are provided by the design of the unit.Boiler water is permitted to seep slowly from the small holethrough the restricted space between the contact surfaces of thetest specimen and the groove in the block. As this extremelyslow flow takes place towa
23、rd atmospheric pressure, the heat inthe metal and in the liquid causes progressive evaporation toproduce an increasingly concentrated solution. When thedetector is properly adjusted, concentrated boiler water is incontact with the stressed test surface of the specimen, thusproviding the necessary fa
24、ctor to determine whether the boilerwater can cause embrittlement cracking.5. Significance and Use5.1 Embrittlement is a form of intercrystalline cracking thatis associated with the exposure of boiler steel to a combinationof physical and chemical factors. For embrittlement of boilermetal to occur,
25、the metal must be under stress, it must be at thesite of a leak, and it must be exposed to the concentrated boilerwater. In addition, the boiler water must be embrittling innature. The precise chemical causes of the embrittling nature ofsome waters is not well understood. Experience has shown thatce
26、rtain waters exhibit an embrittling characteristic while othersdo not.5.2 Because embrittlement is a form of cracking, it is nearlyimpossible to detect in an operating boiler until a failure hasoccured. In general, cracking failures tend to be sudden, andoften with serious consequences. This practic
27、e offers a way todetermine whether a particular water is embrittling or not. Italso makes it possible to determine if specific treatment actionshave rendered the water nonembrittling.6. Apparatus6.1 Embrittlement DetectorThe embrittlement detectorshall consist of the unit, complete with steel specim
28、en, asshown assembled in cross section in Fig. 1 and as the installedunit in Fig. 2. The principal parts consist of a rectangular blockbase through which the water circulates and in which a groovehas been machined to receive the test specimen, a testspecimen, and a clamping plate which fits over fou
29、r stud boltsin the block. When the nuts on the stud bolts are tightened, thepressure of the clamping plate molds the test specimen to thecontour of the groove, thus stressing in tension the surface ofthe specimen. Working drawings (Note 4) showing the dimen-sions of all the machined parts are shown
30、in Figs. 3-5.Accuratemachining of the groove with respect to the small hole throughwhich the boiler water is brought to the test surface of thespecimen is especially important.6.2 WrenchesAn extra-heavy box-type wrench of 27-mm(1116-in.) opening is recommended for assembling and adjust-ing the unit.
31、 A lighter box-type wrench of 19-mm (34-in.)opening is recommended for the hexagonal head of theadjusting screw in the end of the specimen.6.3 Jig for Bending SpecimenA jig as shown in Fig. 6,orits equivalent, is recommended for bending the specimen witha hydraulic press at the end of the test to re
32、veal cracks that mayhave been formed but are too fine to be visible withoutadditional stressing of the steel surface. Other devices may besubstituted to effect the same purpose of bending the specimenuniformly in the proper place without injuring the surface to bestudied (Note 5). A vise and sledge
33、hammer shall not be used.FIG. 1 Cross-Section of Embrittlement DetectorFIG. 2 Embrittlement Detector InstalledD807052NOTE 5The surface to be studied is the stressed area, which starts 6mm (14 in.) above the spot corresponding to the opening in the test blockand extends about 25 mm (1 in.) toward the
34、 adjusting screw.7. Reagents7.1 Purity of ReagentsUnless otherwise indicated, refer-ences to water shall be understood to mean reagent waterconforming to Type IV of Specification D 1193.in. mm in. mm in. mm in. mm164 0.391116 17.46 1316 30 214 5718 3.172332 18.25 114 31.7 238 60316 4.7634 19 11116 4
35、2.8 212 63.5516 7.931316 20.63 134 44.4 2916 6538 9.5278 22.22 11316 46 318 792764 10.71 1 25.4 178 47.6 312 8912 12.7 118 28.6 2 50.8 5 12758 15.87FIG. 3 Dimensional Details of Base Block of Embrittlement Detectorin. mm in. mm18 3.1738 22.22516 7.93 1 25.458 15.87 138 3534 19 178 47.61316 20.63 312
36、 89FIG. 4 Dimensional Details of Clamping Plate of EmbrittlementDetectorin. mm in. mm0.010364120.251.1912.734519127FIG. 5 Dimensional Details of Test SpecimenD8070538. Procedure8.1 Test Specimens8.1.1 Cut test specimens 13 by 19 by 127 mm (12 by34 by5 in.) from 13 by 19-mm (12 by34-in.) cold-finishe
37、d bar stock(Note 6 and Note 7) conforming to Grade 1020 of SpecificationA 108.NOTE 6Where specimens of cold-rolled steel have been cracked,similar specimens machined from boiler plate conforming to SpecificationA 515/A 515M, or hot-rolled steel of comparable composition may betested to determine the
38、 severity of the embrittling condition. Hot-rolledsteel has proved less susceptible to cracking than cold-rolled steel.NOTE 7Alloy steels are often more susceptible for cracking than thestandard cold-rolled steel specified for test specimens. Where the watertested is used in alloy-steel boilers, it
39、is desirable that the test specimen beprepared from the same material or from bars of similar composition andphysical properties.8.1.2 Finish the test surface of the specimen by eithergrinding with a surface grinder to a finish comparable to thatproduced by No. 2 metallographic polishing paper, or m
40、illingto remove surface imperfections and smoothing with No. 2metallographic paper to remove the cutter marks. Grind andpolish along the length of the specimen. If the specimensurface still shows visible flaws, such as holes, oxide, or rollingmarks, after 0.2 mm (0.01 in.) has been removed, discard
41、thespecimen and prepare another one.8.1.3 Bevel the edges of the test surface 5, as shown in Fig.5.8.1.4 Center the threaded hole in the specimen for theadjusting screw and tap as specified in Fig. 5 so that the capscrew is perpendicular to the surface. The adjusting screw shallbe sufficiently free
42、so that it can be turned easily with thefingers.NOTE 8Specimens that have been prepared in accordance with thedirections given in Section 8 may be obtained from the major water-treating companies.8.2 Assembly of Specimen and Detector8.2.1 When a new specimen is to be installed in the detector(Note 9
43、), clean the block, especially the surface of the groove,with hot water to dissolve soluble solids, and scrape lightly toremove less soluble incrustations. Polish the groove with fineemery cloth. Finally open the inlet valve for an instant to makesure that the small leakage hole is cleaned out, then
44、 wipe thegroove clean. Treat the stud threads with graphite suspended inoil (Note 10).NOTE 9When received from the manufacturer the detector is alreadyassembled with the specimen in position and should be steam tight. It isrecommended that the specimen not be removed from the detector untilafter the
45、 first test is completed.NOTE 10Alittle graphite suspended in oil applied to the threads of thestuds and the adjusting screw will minimize seizing. Use kerosine insteadof oil if the pressure is greater than 3.5 MPa (500 psi).8.2.2 To assemble the specimen and the detector, center thespecimen with th
46、e smoothed surface facing the groove of theblock so that the end with the adjusting screw hole is flush withthe end of the block not grooved. Place the clamping plate overthe studs, with the beveled edge inward and toward the end ofthe specimen containing the adjusting screw. Place the washersand nu
47、ts on the studs. Tighten alternately and evenly first thenuts on the top pairs of studs (Note 10) in the center of thedetector block, thus forcing the surface of the test specimen toconform to the curvature of the groove. Then tighten the nutson the bottom pair of studs. Finally tighten the nuts on
48、the toppair of studs to bring the surfaces close enough together so thatthe small hole in the detector block groove is sealed.NOTE 11There shall be no leakage from the detector when the valvesare opened and water at full boiler pressure flows through the block.8.2.3 Insert the adjusting screw in the
49、 specimen and turn itdown with the fingers until it just touches the block.8.3 Installation of Detector8.3.1 Connect the assembled detector to the operating boilerso that boiler water will circulate through the block (Note 12).Flush clean the inlet line to the detector before the detector isattached.NOTE 12The detector may be installed in a bypass to a continuousblow-down line or in a recirculating line if one is available. The effluentfrom the detector may be returned to the boiler or discharged to waste.8.3.2 Maint
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