1、Designation: E1139/E1139M 12E1139/E1139M 17Standard Practice forContinuous Monitoring of Acoustic Emission from MetalPressure Boundaries1This standard is issued under the fixed designation E1139/E1139M; the number immediately following the designation indicates the yearof original adoption or, in th
2、e case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This practice provides guidelines for continuous monitoring of acoustic emission (AE)
3、 from metal pressure boundaries inindustrial systems during operation. Examples are pressure vessels, piping, and other system components which serve to containsystem pressure. Pressure boundaries other than metal, such as composites, are specifically not covered by this document.1.2 The functions o
4、f AE monitoring are to detect, locate, and characterize AE sources to provide data to evaluate theirsignificance relative to pressure boundary integrity. These sources are those activated during system operation, that is, no specialstimulus is applied to produce AE. Other methods of nondestructive t
5、esting (NDT) may be used, when the pressure boundary isaccessible, to further evaluate or substantiate the significance of detected AE sources.1.3 UnitsThe values stated in either SI units or inch-pound units are to be regarded as standard. The values stated in eachsystem may not be exact equivalent
6、s; therefore, each system shall be used independently of the other. Combining values from thetwo systems may result in non-conformance with the standards.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of
7、this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. For specific precautionary statements, see Section 6.1.5 This international standard was developed in accordance with internationally recognized principles on sta
8、ndardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2E543 Specification for Agencies Performing Non
9、destructive TestingE569 Practice for Acoustic Emission Monitoring of Structures During Controlled StimulationE650 Guide for Mounting Piezoelectric Acoustic Emission SensorsE750 Practice for Characterizing Acoustic Emission InstrumentationE976 Guide for Determining the Reproducibility of Acoustic Emi
10、ssion Sensor ResponseE1316 Terminology for Nondestructive ExaminationsE2374 Guide for Acoustic Emission System Performance Verification2.2 Aerospace Industries Association:3NAS-410 Certification and Qualification of Nondestructive Testing Personnel2.3 Other Documents:4SNT-TC-1A Recommended Practice
11、for Nondestructive Testing Personnel Qualification and CertificationANSI/ASNT CP-189 ASNT Standard for Qualification and Certification of Nondestructive Testing Personnel2.4 ISO Standard:5ISO 9712 Non-Destructive Testing: Qualification and Certification of NDT Personnel1 This practice is under the j
12、urisdiction ofASTM Committee E07 on Nondestructive Testing and is the direct responsibility of Subcommittee E07.04 on Acoustic EmissionMethod.Current edition approved June 15, 2012June 1, 2017. Published July 2012June 2017. Originally approved in 1987. Last previous edition approved in 20072012 asE1
13、193 - 07.E1193 - 12. DOI: 10.1520/E1139-12.10.1520/E1139-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3
14、 Available from Aerospace Industries Association of America, Inc. (AIA), 1000 Wilson Blvd., Suite 1700, Arlington, VA 22209-3928, http:/www.aia-aerospace.org.4 Available from American Society for Nondestructive Testing (ASNT), P.O. Box 28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http:/www.as
15、nt.org.5 Available from International Organization for Standardization (ISO), ISO Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva,Switzerland, http:/www.iso.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an in
16、dication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately 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
17、 considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this practice, ref
18、er to Terminology E1316.3.2 Definitions of Terms Specific to This Standard:3.2.1 continuous monitoringthe process of monitoring a pressure boundary continuously to detect acoustic emission duringsystem operation and also during system shut-down testing such as hydrostatic testing.3.2.2 raw datadata
19、values determined directly from measurement of analog inputs. These could include emission count oremission event count, or both, relative time of signal arrival at different sensors (delta time), signal rise time, peak signal amplitude,RMS signal level, pressure system pressure and temperature, and
20、 the like.3.2.3 processed datadata resulting from analysis of raw data. Included would be AE source location coordinates, AE versustime from a given source area, AE signal amplitude versus time, and the like.4. Summary of Practice4.1 This practice describes the use of a passive monitoring system to
21、detect, locate, and characterize AE sources, in order toevaluate their significance to the integrity of metal pressure boundaries.4.2 The practice provides guidelines for selection, qualification, verification, and installation of the AE monitoring system.Qualification of personnel is also addressed
22、.4.3 The practice provides guidelines for using the AE information to estimate the significance of a detected AE source withrespect to continued pressure system operation.5. Significance and Use5.1 Acoustic emission examination of a structure requires application of a mechanical or thermal stimulus.
23、 In this case, thesystem operating conditions provide the stimulation. During operation of the pressurized system, AE from active discontinuitiessuch as cracks or from other acoustic sources such as leakage of high-pressure, high-temperature fluids can be detected by aninstrumentation system using s
24、ensors mounted on the structure. The sensors are acoustically coupled to the surface of the structureby means of a couplant material or pressure on the interface between the sensing device and the structure. This facilitates thetransmission of acoustic energy to the sensor. When the sensors are exci
25、ted by acoustic emission energy, they transform themechanical excitations into electrical signals. The signals from a detected AE source are electronically conditioned and processedto produce information relative to source location and other parameters needed for AE source characterization and evalu
26、ation.5.2 AE monitoring on a continuous basis is a currently available method for continuous surveillance of a structure to assess itscontinued integrity. The use of AE monitoring in this context is to identify the existence and location of AE sources. Also,information is provided to facilitate esti
27、mating the significance of the detected AE source relative to continued pressure systemoperation.5.3 Source location accuracy is influenced by factors that affect elastic wave propagation, by sensor coupling, and by signalprocessor settings.5.4 It is possible to measureAE and identifyAE source locat
28、ions of indications that cannot be detected by other NDT methods,due to factors related to methodological, material, or structural characteristics.5.5 In addition to immediate evaluation of the AE sources, a permanent record of the total data collected (AE plus pressuresystem parameters measured) pr
29、ovides an archival record which can be re-evaluated.6. Hazards6.1 WarningApplication of this practice will inherently involve work in an operating plant. This may involve potentialexposure to hazardous materials and equipment and, in the case of nuclear power plants, exposure to nuclear radiation. A
30、 writtensafety plan shall be prepared for each monitoring installation which defines requirements to be observed to protect personnel safety,safety of the plant system, and to meet administrative and legal needs. This plan shall be approved by all parties prior to start ofwork on the plant.7. Basis
31、of Application7.1 The following items are subject to contractual agreement between the parties using or referencing this practice.7.2 Personnel Qualification7.2.1 If specified in the contractual agreement, personnel performing examinations to this practice shall be qualified inaccordance with a nati
32、onally or internationally recognized NDT personnel qualification practice or standard such as ANSI/ASNT-CP-189, SNT-TC-1A, NAS-410, ISO 9712, or a similar document and certified by the employer or certifying agency, as applicable.The practice or standard used and its applicable revision shall be ide
33、ntified in the contractual agreement between the using parties.E1139/E1139M 1727.3 Qualification of Nondestructive Agencies7.3.1 If specified in the contractual agreement, NDT agencies shall be qualified and evaluated as described in Practice E543.The applicable edition of Practice E543 shall be spe
34、cified in the contractual agreement.7.4 Qualification of Nondestructive Testing AgenciesIf specified in the contractual agreement, NDT agencies shall be qualifiedand evaluated as described in Practice E543. The applicable edition of E543 shall be specified in the contractual agreement.7.5 Timing of
35、ExaminationThe timing of examination shall be continuous, in accordance with 1.1 unless otherwise specified.7.6 Extent of ExaminationThe extent of examination shall be that part of the pressure boundary in the coverage range of themounted acoustic emission sensors, unless otherwise specified.7.7 Rep
36、orting Criteria/Acceptance CriteriaReporting criteria for the examination results shall be in accordance with Section14 unless otherwise specified. Since acceptance criteria (for example, for reference radiographs) are not specified in this practice,they shall be specified in the contractual agreeme
37、nt.7.8 Reexamination of Repaired/Reworked ItemsReexamination of repaired/reworked items is not addressed in this practiceand if required shall be specified in the contractual agreement.7.9 Routine operation of the acoustic emission system for collection and a cursory review of the data may be perfor
38、med by acompetent plant engineer not necessarily specialized in acoustic emission. However, acoustic emission system operation and datainterpretation should be verified by a qualified acoustic emission specialist on approximately six-month intervals or sooner if thesystem appears to be malfunctionin
39、g or the data appear unusual.8. Monitoring System Functional Requirements and Qualification8.1 Functional Requirements:8.1.1 The monitoring system must include the functional capabilities shown in Fig. 1 which also shows a suggested sequenceof monitoring system functions.8.1.2 Signal DetectionThe AE
40、 sensor together with the acoustic coupling to the structure must have sensitivity sufficient todetect AE signals while the pressure system is operating. In most cases, this determination must be performed when the pressuresystem is not operating. AE system response to normal operational noise, whic
41、h must be considered here, is discussed in 9.1. Onemethod of performing the required evaluation is to use a pencil lead break as a signal source. With the sensor in place andconnected to the system, the response at the amplifier output to fracturing a 0.3-mm 0.012 in. pencil lead against the surface
42、 beingmonitored, at a distance of 150 to 300 mm 6 to 12 in. from the sensor should show a minimum signal-to-noise (electronic plusprocess noise) ratio of 4 to 1 in the frequency range suitable for the planned monitoring environment. A differential sensor shouldbe considered to minimize interference
43、from electronic transients. The sensor must be capable of withstanding the monitoringenvironment (temperature, moisture, nuclear radiation, mechanical vibration, and the like) for an extended period of continuousexposure. The minimum length of this period will be dictated by accessibility to the loc
44、ation to change sensors, and by economicconsiderations.8.1.3 Signal AmplificationFor those AE systems that use gain adjustments, appropriate signal amplification in the range of 0to 60 dB is usually required to achieve an adequate AE signal level for measurement of signal parameters in digital AE sy
45、stems.Due to the very small magnitude of energy involved in an AE source, it is desirable to locate the signal amplification as near asFIG. 1 Functional Flow DiagramContinuous AE Monitoring SystemE1139/E1139M 173possible to the output of the sensor. This is beneficial in controlling noise interferen
46、ce and AE signal transmission loss. Thesepreamplifiers must have low inherent electronic background noise. Resistance of the amplifier circuits to the environment(temperature, moisture, nuclear radiation, mechanical vibration, and the like) must be considered and appropriate steps taken toprotect th
47、em.NOTE 1When used herein, peak means zero to peak voltage.8.1.4 Monitoring Frequency BandThe frequency response of the sensor or amplifier combination must be selected for thegiven application. The AE signal being a transient pulse is detectable over a broad range of frequencies. Because the acoust
48、icattenuation in engineering materials is frequency dependent, it is desirable to use a low monitoring frequency (50 to 100 kHz) tomaximize the distance from the AE source over which the AE event can be detected. The low end of the monitoring frequencywill usually be controlled by the background noi
49、se present in the monitoring environment. In some applications such as operatingnuclear reactors, the background noise may require a low frequency cut-off point of 400 to 500 kHz. In cases of severe continuousbackground noise, inductive tuning of the sensor at the preamplifier input may be effective. The high end of the frequency responseband may be limited to 1.0 MHz to help reduce amplifier electronic noise.8.1.5 Signal Measurement:8.1.5.1 The signal measurement section will receive the fully-amplified analog signal. Generally its operation will be controll
