1、Designation:E113907 Designation: E1139/E1139M 12Standard 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,
2、in the 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
3、 (AE) 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 functi
4、ons of 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 nondestruct
5、ive testing (NDT) may be used, when the pressure boundary isaccessible, to further evaluate or substantiate the significance of detected AE sources.1.31.3 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 eq
6、uivalents; 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
7、user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. For specific precautionary statements, see Section 6.2. Referenced Documents2.1 ASTM Standards:2E543 Specification for Agencies Performing Nondestructive
8、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 Emission Sensor
9、 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 for Nondestr
10、uctive Testing Personnel Qualification and CertificationANSI/ASNT CP-189 ASNT Standard for Qualification and Certification of Nondestructive Testing Personnel3. Terminology3.1Definitions:3.1 Definitions:3.1.1 For definitions of terms used in this practice, refer to Terminology E1316.3.2 Definitions
11、of Terms Specific to This Standard:1This practice is under the jurisdiction of ASTM Committee E07 on Nondestructive Testing and is the direct responsibility of Subcommittee E07.04 on Acoustic EmissionMethod.Current edition approved Dec. 1, 2007. Published January 2008. Originally approved in 1987. L
12、ast previous edition approved in 2002 as E1193-02. DOI:10.1520/E1139-07.Current edition approved June 15, 2012. Published July 2012. Originally approved in 1987. Last previous edition approved in 2007 as E1193 - 07. DOI: 10.1520/E1139-12.2For referenced ASTM standards, visit the ASTM website, www.as
13、tm.org, or contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3Available from Aerospace Industries Association of America, Inc. (AIA), 1000 Wilson Blvd., Suite 1700, Arlington, VA 222
14、09-3928, http:/www.aia-aerospace.org.4Available from American Society for Nondestructive Testing (ASNT), P.O. Box 28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http:/www.asnt.org.1This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication o
15、f 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 considere
16、d the official document.*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.1 continuous monitoringthe process of monitoring a pressure boundary continuously to detect
17、acoustic emission duringsystem operation and also during system shut-down testing such as hydrostatic testing.3.2.2 raw datadata values determined directly from measurement of analog inputs. These could include emission count oremission event count, or both, relative time of signal arrival at differ
18、ent sensors (delta time), signal rise time, peak signal amplitude,RMS signal level, pressure system pressure and temperature, and 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
19、 amplitude versus time, and the like.4. Summary of Practice4.1 This practice describes the use of a passive monitoring system to 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
20、selection, qualification, verification, and installation of the AE monitoring system.Qualification of personnel is also addressed.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.
21、5. Significance and Use5.1 Acoustic emission examination of a structure requires application of a mechanical or thermal stimulus. In this case, thesystem operating conditions provide the stimulation. During operation of the pressurized system, AE from active discontinuitiessuch as cracks or from oth
22、er acoustic sources such as leakage of high-pressure, high-temperature fluids can be detected by aninstrumentation system using sensors 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 t
23、he sensing device and the structure. This facilitates thetransmission of acoustic energy to the sensor. When the sensors are excited by acoustic emission energy, they transform themechanical excitations into electrical signals. The signals from a detected AE source are electronically conditioned and
24、 processedto produce information relative to source location and other parameters needed for AE source characterization and evaluation.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 mo
25、nitoring in this context is to identify the existence and location of AE sources. Also,information is provided to facilitate estimating the significance of the detected AE source relative to continued pressure systemoperation.5.3 Source location accuracy is influenced by factors that affect elastic
26、wave propagation, by sensor coupling, and by signalprocessor settings.5.4 It is possible to measure AE and identify AE source locations 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 imm
27、ediate evaluation of the AE sources, a permanent record of the total data collected (AE plus pressuresystem parameters measured) provides 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 involv
28、e potentialexposure to hazardous materials and equipment and, in the case of nuclear power plants, exposure to nuclear radiation. A writtensafety plan shall be prepared for each monitoring installation which defines requirements to be observed to protect personnel safety,safety of the plant system,
29、and to meet administrative and legal needs. This plan shall be approved by all parties prior to start ofwork on the plant.7. Basis 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 spe
30、cified in the contractual agreement, personnel performing examinations to this practice shall be qualified inaccordance with a nationally or internationally recognized NDT personnel qualification practice or standard such as ANSI/ASNT-CP-189, SNT-TC-1A, NAS-410, or a similar document and certified b
31、y the employer or certifying agency, as applicable. Thepractice or standard used and its applicable revision shall be identified in the contractual agreement between the using parties.7.3 Qualification of Nondestructive Agencies7.3.1 If specified in the contractual agreement, NDT agencies shall be q
32、ualified and evaluated as described in Practice E543.The applicable edition of Practice E543 shall be specified in the contractual agreement.7.4 Qualification of Nondestructive Testing AgenciesIf specified in the contractual agreement, NDT agencies shall bequalified and evaluated as described in Pra
33、ctice E543. The applicable edition of E543 shall be specified in the contractualagreement.7.5 Timing of 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 bo
34、undary in the coverage range of themounted acoustic emission sensors, unless otherwise specified.E1139/E1139M 1227.7 Reporting Criteria/Acceptance CriteriaReporting criteria for the examination results shall be in accordance with Section14 unless otherwise specified. Since acceptance criteria (for e
35、xample, for reference radiographs) are not specified in this practice,they shall be specified in the contractual agreement.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 agree
36、ment.7.9 Routine operation of the acoustic emission system for collection and a cursory review of the data may be performed by acompetent plant engineer not necessarily specialized in acoustic emission. However, acoustic emission system operation and datainterpretation should be verified by a qualif
37、ied acoustic emission specialist on approximately six-month intervals or sooner if thesystem appears to be malfunctioning 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 capab
38、ilities shown in Fig. 1 which also shows a suggested sequenceof monitoring system functions.8.1.2 Signal DetectionThe AE 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 determ
39、ination must be performed when the pressuresystem is not operating. AE system response to normal operational noise, which 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 andconnec
40、ted to the amplifier(s),system, the response at the amplifier output to fracturing a 0.3-mm 0.012 in. pencil lead against thesurface being monitored, at a distance of 150 to 300 mm (66 to 12 in.)in. from the sensor should show a minimum signal-to-noise(electronic plus process noise) ratio of 4 to 1
41、in athe frequency range suitable for the planned monitoring environment. Adifferential sensor should be considered to minimize interference from electronic transients. The sensor must be capable ofwithstanding the monitoring environment (temperature, moisture, nuclear radiation, mechanical vibration
42、, and the like) for anextended period of continuous exposure. The minimum length of this period will be dictated by accessibility to the location tochange sensors, and by economic considerations.8.1.3 Signal AmplificationFor those AE systems that use gain adjustments, appropriate signal amplificatio
43、n 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 systems.Due to the very small magnitude of energy involved in an AE source, it is desirable to locate the signal amplification as near aspossible to the output of
44、 the sensor. This is beneficial in controlling noise interference 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 li
45、ke) must be considered and appropriate steps taken toprotect them.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 d
46、etectable over a broad range of frequencies. Because the acousticattenuation 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 monit
47、oring frequencyFIG. 1 Functional Flow DiagramContinuous AE MonitoringSystemE1139/E1139M 123will usually be controlled by the background noise present in the monitoring environment. In some applications such as operatingnuclear reactors, the background noise may require a low frequency cut-off point
48、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 meas
49、urement section will receive the fully-amplified analog signal. Generally its operation will be controlledby a voltage threshold circuit which will limit accepted data to that exceeding the voltage amplitude threshold. AE parametersmeasured may include AE count, AE event count, signal amplitude, time from threshold crossing to signal peak, signal duration,difference in time of signal arrival at various sensors making up a source location array, clock time, data, and the value of anyprocess system parameters (temperature, pressure, strain, and the like) availabl
