1、Designation: E2598 07Standard Practice forAcoustic Emission Examination of Cast Iron Yankee andSteam Heated Paper Dryers1This standard is issued under the fixed designation E2598; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、 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 provides guidelines for carrying out acous-tic emission (AE) examinations of Yankee and Steam
3、HeatedPaper Dryers (SHPD) of the type to make tissue, paper, andpaperboard products.1.2 This practice requires pressurization to levels usedduring normal operation. The pressurization medium may behigh temperature steam, air, or gas. The dryer is also subjectedto significant stresses during the heat
4、ing up and cooling downperiods of operation. Acoustic Emission data maybe collectedduring these time periods but this testing is beyond the scopeof this document.1.3 The AE measurements are used to detect, as well as,localize emission sources. Other methods of nondestructivetesting (NDT) may be used
5、 to further evaluate the significanceof acoustic emission sources.1.4 This 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 app
6、lica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2A 278/A 278M Specification for Gray Iron Castings forPressure-Containing Parts for Temperatures Up to 650F(350C)E 543 Specification for Agencies Performing Nondestruc-tive TestingE 569 Practice for Acoustic
7、 Emission Monitoring of Struc-tures During Controlled StimulationE 650 Guide for Mounting Piezoelectric Acoustic EmissionSensorsE 976 Guide for Determining the Reproducibility ofAcous-tic Emission Sensor ResponseE 1316 Terminology for Nondestructive ExaminationsE 2374 Guide for Acoustic Emission Sys
8、tem PerformanceVerification2.2 ASNT Standards:3SNT-TC-1A Recommended Practice for NondestructiveTesting PersonnelANSI/ASNT CP-189 Standard for Qualification and Certi-fication of Nondestructive Testing Personnel3. Terminology3.1 DefinitionsSee Terminology E 1316 for general ter-minology applicable t
9、o this practice.4. Summary of Practice4.1 Each mounted sensor, on the cast iron vessel, monitorswhile the vessel is stationary and pressurized to normaloperating pressure. The vessel may be at ambient, or operating(250F-450F) temperature.4.2 Each mounted AE sensor is connected to an acousticemission
10、 signal processor. After a monitoring period (up to 10minutes) and pre-examination sensor sensitivity checks, pres-surization can begin.4.3 Location4.3.1 Zone LocationEach channel shall have the samesystem examination threshold. A simulated AE source gener-ated anywhere on the vessel shall be detect
11、ed by at least onesensor.4.3.2 Source LocationAll location data resulting fromanalysis shall be presented in a manner consistent with thepreviously established calibration accuracy. The simulated AEsource generated in each structure mounted sensor array shallbe detected by the minimum number of sens
12、ors required tolocate the source within 65 % of sensor spacing.4.4 Due to the potential for gasketed interfaces (at theheads/manway), multiple metal combinations (metalspray, caststeel-cast iron combinations), high vessel temperature, or1This practice is under the jurisdiction of ASTM Committee E07
13、on Nonde-structive Testing and is the direct responsibility of Subcommittee E07.04 onAcoustic Emission Method.Current edition approved Dec. 1, 2007. Published January 2008.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For An
14、nual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available fromAmerican Society for NondestructiveTesting (ASNT), P.O. Box28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http:/www.asnt.org.1Copyright ASTM International, 100 Barr Harb
15、or Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.random variations in the material velocity of cast iron, accuratesource location (65 % sensor spacing) may not always bepossible.4.5 Once the AE sensor source is localized, further evalua-tion is begun by observing a “history” of
16、 events involving thearea Head tilt (corrosion induced head strain), leak repair,objects through the nip (working contact with another roll),etc. This may give further direction to the selection of theNDE method to use for follow-up examination of the AEindication area.4.6 Secondary examination esta
17、blishes presence of flawsand measures flaw dimensions.4.7 Cast ironYankee dryers can be up to 22 feet in diameter,24 feet long, and weigh 100 tons, or more. Vessel thicknessmeasurements are available from the paper/tissue machineoperator. Cast iron is a brittle metal and has no specific yieldpoint.
18、Yankee dryers must maintain specific dimensional tol-erances. When a pressurized Yankee or steam heated paperdryer (SHPD) remains stationary, it fills with condensate at arapid rate. In an hour, a steam pressurizedYankee or SHPD canfill half way with condensate, doubling the weight on theframe, and
19、the floor. Some Yankee owners have corporaterequirements that a cast iron Yankee dryer remain stationaryfor12 hour, then rotation is required. Permission is required, ifthe Yankee is to remain stationary for more time. This issueshould be discussed with the responsible person prior to theexamination
20、.4.8 Yankee dryers operate under a heated hood. The hood isin close proximity to the Yankee shell and allows only inchesof clearance for the top half of the vessel.4.9 Cast iron steam heated paper machine dryers are 6 feetin diameter, or more, and may be 30 feet long.4.10 Gray cast iron experiences
21、a continuing reduction inelastic modulus as it is stressed to increasing higher levels. It isprudent not to stress grey cast iron material beyond itsoperating stress level.4.11 Flaws to be found are the same as those in any cast andmachined product. Attempts have been made to characterizestrength pr
22、operties of cast irons in compact tension tests. In aTAPPI sponsored laboratory study, two out of three cast ironcompact tension specimens experienced unplanned failures.From that experience it was cautioned that “cracks initiated andgrew faster than expected resulting in brittle fracture before the
23、process could be halted. The failure of these two couponsdemonstrated the rate in which cracks can grow in thesematerials and the materials inability to stop a crack once itbegins to grow. In each case, crack advance was extremelyrapid and without warning.44.12 Maximum Examination PressureMaximum Al
24、low-able Working Pressure for cast iron vessels is set based onASME (Section VIII) pressure calculations based on thickness,radius, and material strength values, and will not exceed 160psi and 450F (A278). When vessels are pressurized, anoma-lies produce emission at pressures less than normal fill p
25、res-sure. Historically, if there is damage in a cast iron pressureboundary, AE activity will begin at load/stress levels less than50 % of operating. Defects as small as18 in. have been foundusing AE, during steam pressurization to operating pressure.4.13 Pressure increments should not exceed 5 psi/m
26、inute. Ifpressurization medium is to be steam, the Yankee should havebeen through the warm-up process.4.14 Yankee dryers may receive a subsequent examination,if necessary, after the Yankee is rotated to remove anycondensate present.4.15 Pressurization SchedulePressurization should pro-ceed at rates
27、that allow achieving maximum examinationpressure within a 30 minute period. During pressurization,pressure holds are not necessary; however, they may be usefulfor reasons other than measurement of AE. Pressure hold uponachieving maximum examination pressure may be up to 30minutes.4.16 Excess backgro
28、und noise may distortAE data or renderthe AE measurements useless. Users must be aware of thefollowing common sources of background noise: (measurableflow noise); mechanical contact with the vessel by objects;electromagnetic interference (EMI) from cranes, and radiofrequency interference (RFI) from
29、nearby broadcasting facili-ties and from other sources; leaks at pipe or hose connections,or rain drops. This practice should not be used if backgroundnoise cannot be eliminated or controlled.4.17 Other nondestructive test methods may be used toevaluate the significance of AE sources. Magnetic parti
30、cle,ultrasonic, and radiographic examinations have been used toestablish circumferential position, depth, and dimensions offlaws that produce AE. Procedures for using other NDTmethods are beyond the scope of this practice.5. Basis of Application5.1 The following items are subject to contractual agre
31、e-ment between the parties using or referencing this standard.5.2 Personnel Qualification5.2.1 If specified in the contractual agreement, personnelperforming examinations to this standard shall be qualified inaccordance with a nationally or internationally recognizedNDT personnel qualification pract
32、ice or standard such asANSI/ASNT-CP-189, SNT-TC-1A, NAS-410, or a similardocument and certified by the employer or certifying agency,as applicable. The practice or standard used and its applicablerevision shall be identified in the contractual agreement be-tween the using parties.5.3 Qualification o
33、f Nondestructive AgenciesIf specifiedin the contractual agreement, NDT agencies shall be qualifiedand evaluated as described in Practice E 543. The applicableedition of Practice E 543 shall be specified in the contractualagreement.5.4 Procedures and TechniquesThe procedures and tech-niques to be uti
34、lized shall be as specified in the contractualagreement.5.5 Extent of ExaminationThe extent of examinationincludes the entire pressure vessel unless otherwise specified.5.6 Reporting Criteria/AE Evaluation CriteriaExamination results will be reported and compared with AEevaluation criteria. Since ac
35、ceptance criteria (for example,4Alleveto, C., and Williams D., Acoustic Emission Evaluation of Yankee DryerShell Material, 1991 TAPPI Engineering Conference Proceedings, pages 475-480.E2598 072reference radiographs) are not specified in this practice, theyshall be specified in the contractual agreem
36、ent.6. Apparatus6.1 Essential features of the apparatus required for thispractice are provided in Fig. 1. Full specifications are inAnnexA1.6.2 Couplant must be used to acoustically connect sensorsto the vessel surface. Adhesives that have acceptable acousticproperties, and adhesives used in combina
37、tion with traditionalcouplants, are acceptable.6.3 Sensors may be held in place with magnets, adhesivetape, or other mechanical means. High temperature waveguidesmay be used but they cannot be welded to the shell of the drum.The attachment method to be used should be reviewed with thedryer owner pri
38、or to use.6.4 TheAE sensors are used to detect stress waves producedby cast iron anomalies. Sensors must be held in contact withthe vessel wall to ensure adequate acoustic coupling (seeE 650). Sensors shall be capable of operating in the examina-tion environment (Some operating environments may be u
39、p to450F (232C).6.5 The preamplifier should be kept as far as possible awayfrom the heat. If a separate preamplifier is used, cable length,between sensor and preamp, must not exceed 6 ft (1.83 m).6.6 Power/signal cable length, (that is, the maximum cablelength between the preamplifier and processor)
40、 should notexceed the manufacturers specification for the device.6.7 Signal processors are computerized instruments withindependent channels that filter, measure, and convert analoginformation into digital form for display and permanent stor-age.Asignal processor must have sufficient speed and capac
41、ityto independently process data from all sensors simultaneously.The signal processor should provide capability to digitally filterdata for replay.6.7.1 A video monitor should display processed examina-tion data in various formats. Display format may be selected bythe equipment operator.6.7.2 A digi
42、tal data storage device, such as a floppy disk,CD, DVD, flash drive or other electronic storage media may beused to provide data for replay or for archives.6.7.3 Hard copy capability should be available from agraphics/line printer or equivalent device.7. Safety Precautions7.1 As in any pressurizatio
43、n of metal vessels, ambienttemperature should not be below the ductile-brittle transitiontemperature of the pressure vessel construction material.7.2 This document does not address personnel safety con-cerns when examining high temperature items.8. Calibration and Standardization8.1 Annual calibrati
44、on and verification of AE sensors,preamplifiers (if applicable), signal processor, and AE elec-tronic waveform generator (or simulator) should be performed.Equipment should be adjusted so that it conforms to equipmentmanufacturers specifications. Instruments used for calibra-tions must have current
45、accuracy certification that is traceableto the National Institute for Standards and Technology (NIST).8.2 Routine electronic evaluations must be performed anytime there is concern about signal processor performance. AnAE electronic waveform generator or simulator, should be usedin making evaluations
46、. Each signal processor channel mustrespond with peak amplitude reading within 62dBoftheelectronic waveform generator output.8.3 A system performance verification must be conductedimmediately before, and immediately after, each examination.A performance verification uses a mechanical device to induc
47、estress waves into the material under examination, at a specifieddistance from each sensor. Induced stress waves stimulate aFIG. 1 AE System Block Diagram with Essential FeaturesE2598 073sensor in the same way as emission from a flaw. Performanceverifications verify performance of the entire system
48、(includingcouplant). (Refer to Guide E 2374 for AE system performanceverification techniques).8.3.1 The preferred technique for conducting a performanceverification is a pencil lead break (PLB). Lead should bebroken on the material surface at a specified distance from eachsensor. The 2H lead, 0.3-mm
49、 diameter, and 2 to 3-mm longshould be used (see Figure 5 of Guide E 976 and GuideE 2374).8.3.2 Auto Sensor Test (AST)An electromechanical devicesuch as a piezoelectric pulser (and sensor which contains thisfunction) can be used in conjunction with pencil lead break asa means to assure system performance. This device can be usedto replace the PLB post examination, system performanceverification. (Refer to Guide E 2374.)8.4 Visually examine accessible exterior surfaces of thevessel. Note observations in examination report.8.5 Use procedures specified in Guide
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