1、Designation: D807 14Standard Practice forAssessing the Tendency of Industrial Boiler Waters toCause Embrittlement (USBM1Embrittlement DetectorMethod)2This standard is issued under the fixed designation D807; 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 () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice,3known as the embrittlement-detectormethod, covers the apparatus an
3、d 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 8.6.NOTE 1The embrittlement detector was designed to reproduce closelythe conditions existing in an actual
4、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 factors ac
5、t 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 thoroughly, w
6、hile 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 after being sub
7、jected 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 this practic
8、e. 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 The values sta
9、ted 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 thesafety concerns, if any, associated with its us
10、e. 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:5A108 Specification for Steel Bar, Carbon and Alloy, Cold-FinishedA515/A515M
11、 Specification for Pressure Vessel Plates, Car-bon Steel, for Intermediate- and Higher-Temperature Ser-viceD1129 Terminology Relating to WaterD1193 Specification for Reagent WaterE3 Guide for Preparation of Metallographic SpecimensE883 Guide for ReflectedLight PhotomicrographyE1351 Practice for Prod
12、uction and Evaluation of FieldMetallographic Replicas3. Terminology3.1 DefinitionsFor definitions of other terms used in thispractice, refer to Terminology D1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 embrittlement cracking, na form of metal failurethat occurs in steam boilers at r
13、iveted joints and at tube ends,the cracking being predominantly intercrystalline.3.2.1.1 DiscussionThis form of cracking, which has beenknown as “caustic embrittlement,” is believed to result fromthe action of certain constituents of concentrated boiler water1United States Bureau of Mines.2This test
14、 method is under the jurisdiction of ASTM Committee D19 on Waterand is the direct responsibility of Subcommittee D19.03 on Sampling Water andWater-Formed Deposits, Analysis of Water for Power Generation and Process Use,On-Line Water Analysis, and Surveillance of Water.Current edition approved Jan. 1
15、, 2014. Published January 2014. Originallyapproved in 1944. Last previous edition approved in 2009 as D807 05 (2009).DOI: 10.1520/D0807-14.3This test method was developed during an investigation conducted under acooperative agreement between the Joint Research Committee on Boiler FeedwaterStudies an
16、d the United States Bureau of Mines. For information on the developmentof this test method reference may be made to the following: Schroeder and Berk,1941 (1);4Schroeder, Berk, and Stoddard, 1941 (2); Transactions of the AmericanSociety of Mechanical Engineers, 1942 (3); Whirl and Purcell, 1942 (4);
17、 and Berkand Schroeder, 1943 (5).5For 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.Copyright ASTM International
18、, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1upon steel under stress. For a detailed discussion as to whatcracking should be considered significant for the purpose ofthis practice, see 8.6.4. Summary of Practice4.1 For embrittlement cracking of the boiler met
19、al 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 at tube ends, and the steel atsuch locations may be highly stressed w
20、hen 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 (Fig. 1), the conditions ofconcentration and stress are provided by the
21、 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 toward atmospheric pressure, the heat inthe metal and in the liquid causes
22、 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 factor to determine whether the boilerwater can cause embrittlement crac
23、king.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, the metal must be under stress, it must be at thesite of a leak, and i
24、t 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 are not well understood. Experience has shownthat certain waters exhibit an embrittling characteristic whileothers do not
25、.5.2 Because embrittlement is a form of cracking, it is nearlyimpossible to detect in an operating boiler until a failure hasoccurred. In general, cracking failures tend to be sudden, andoften with serious consequences. This practice offers a way todetermine whether a particular water is embrittling
26、 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 specimen, asshown assembled in cross section in Fig. 1 and as the installe
27、dunit 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 four stud boltsin the block. When the nuts on the stud bolts are tighte
28、ned, thepressure of the clamping plate molds the test specimen to thecontour of the groove, thus stressing in tension the surface ofthe specimen. Working drawings showing the dimensions of allthe machined parts are shown in Figs. 3-5.Accurate machiningof the groove with respect to the small hole thr
29、ough which theboiler water is brought to the test surface of the specimen isespecially important.6.2 WrenchesAn extra-heavy box-type wrench of 1116-in.(27-mm) opening is recommended for assembling and adjust-ing the unit. A lighter box-type wrench of34-in. (19-mm)opening is recommended for the hexag
30、onal 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 reveal cracks that mayhave been formed but are too fine to be visible withoutaddit
31、ional stressing of the steel surface. Other devices may besubstituted to affect the same purpose of bending the specimenFIG. 1 Cross-Section of Embrittlement Detector FIG. 2 Embrittlement Detector InstalledD807 142uniformly in the proper place without injuring the surface to bestudied (Note 3). A vi
32、se and sledge hammer shall not be used.NOTE 3The surface to be studied is the stressed area, which starts14in. (6 mm) above the spot corresponding to the opening in the test blockand extends about 1 in. (25 mm) toward the adjusting screw.in. mm in. mm in. mm in. mm164 0.391116 17.46 1316 30 214 5718
33、 3.172332 18.25 114 31.7 238 60316 4.7634 19 11116 42.8 212 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.
34、93 1 25.458 15.87 138 3534 19 178 47.61316 20.63 312 89FIG. 4 Dimensional Details of Clamping Plate of EmbrittlementDetectorin. mm in. mm0.010364120.251.1912.734519127FIG. 5 Dimensional Details of Test SpecimenD807 1437. Reagents7.1 Purity of ReagentsUnless otherwise indicated, refer-ences to water
35、shall be understood to mean reagent waterconforming to Type IV of Specification D1193.8. Procedure8.1 Test Specimens:8.1.1 Cut test specimens12 by34 by 5 in. (13 by 19 by 127mm) from12 by34-in. (13 by 19-mm) cold-finished bar stock(Note 4 and Note 5) conforming to Grade 1020 of SpecificationA108.NOT
36、E 4Where specimens of cold-rolled steel have been cracked,similar specimens machined from boiler plate conforming to SpecificationA515/A515M, or hot-rolled steel of comparable composition may betested to determine the severity of the embrittling condition. Hot-rolledsteel has proved less susceptible
37、 to cracking than cold-rolled steel.NOTE 5Alloy 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 is desirable that the test specimen beprepared from the same material or from bars
38、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 millingto remove surface imperfections and smoothing with No. 2metallographic paper
39、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 0.01 in. (0.2 mm) has been removed, discard thespecimen and prepare another one.8.1.3 Bevel the edges of the test surface 5, as
40、 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 so that it can be turned easily with thefingers.NOTE 6Specimens that have been prep
41、ared in accordance with thedirections given in Section 8 may be obtained from the major water-treating companies.8.2 Assembly of Specimen and Detector:8.2.1 When a new specimen is to be installed in the detector(Note 7), clean the block, especially the surface of the groove,with hot water to dissolv
42、e 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 wipe thegroove clean. Treat the stud threads with graphite suspended inoil (Note
43、8).NOTE 7When 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 first test is completed.NOTE 8A little graphite suspended in oil applied to the th
44、reads of thestuds and the adjusting screw will minimize seizing. Use kerosene insteadof oil if the pressure is greater than 500 psi (3.5 MPa).8.2.2 To assemble the specimen and the detector, center thespecimen with the smoothed surface facing the groove of theblock so that the end with the adjusting
45、 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 nuts on the studs. Tighten alternately and evenly first thenuts on the top pairs of s
46、tuds (Note 8) 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 the toppair of studs to bring the surfaces close enough together so thatthe small ho
47、le in the detector block groove is sealed.NOTE 9There 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 specimen and turn itdown with the fingers until it just touches the block.8.3 Instal
48、lation of Detector:8.3.1 Connect the assembled detector to the operating boilerso that boiler water will circulate through the block (Note 10).Flush clean the inlet line to the detector before the detector isattached.NOTE 10The detector may be installed in a bypass to a continuousblow-down line or i
49、n a recirculating line if one is available. The effluentfrom the detector may be returned to the boiler or discharged to waste.8.3.2 Maintain the temperature and pressure of the watercirculating through the detector block substantially the same asthe temperature (Note 11) and pressure of the water in theboiler. Determine the temperature by means of a thermocoupleor thermometer inserted in a small hole provided for it in theblock.NOTE 11It will usually be found necessary to insulate the inlet line toprevent heat loss
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