GOST R 52727-2007
GOST R 52727−2007 Technical diagnostics. Acoustic emission diagnostics. General requirements
GOST R 52727−2007
Group Т59
NATIONAL STANDARD OF THE RUSSIAN FEDERATION
Technical diagnostics
ACOUSTIC EMISSION DIAGNOSTICS
General requirements
Technical diagnostics. Acoustic-emission diagnostics.
General requirements
OKS 77.040.10
Date of introduction 2007−10−01
Preface
The objectives and principles of standardization in the Russian Federation established by the Federal law of 27 December 2002 N 184-FZ «On technical regulation», and rules for the application of national standards of the Russian Federation — GOST R 1.0−2004"Standardization in the Russian Federation. The main provisions"
Data on standard
1 Iyar DEVELOPED by RRC «KI», Samara branch of JSC «Orgenergoneft», FSUE «OKBM them. Afrikantov"
2 SUBMITTED by the Technical Committee for standardization TC 132 «Technical diagnostics"
3 APPROVED AND put INTO EFFECT by the Federal Agency for technical regulation and Metrology of June 14, 2007 N 134-St
4 INTRODUCED FOR THE FIRST TIME
Information about the changes to this standard is published in the annually published index «National standards», and the text changes and amendments — in monthly indexes published information «National standards». In case of revision (replacement) or cancellation of this standard a notification will be published in a monthly information index «National standards». Relevant information, notification and lyrics are also posted in the information system of General use — on the official website of the Federal Agency for technical regulation and Metrology on the Internet
Introduction
Acoustic-emission method relates to acoustic methods of nondestructive control and technical diagnostics. The method is based on the physical phenomenon of emission of stress waves during rapid local reconstruction of the structure of the material. The phenomenon of acoustic emission is observed in a wide range of materials, structures and processes. Spectrum of acoustic emission signals lying in the audible and ultrasonic ranges. The working frequency range of the instrument may vary in the range from 10 kHz to 1 MHz depending on the type, size, acoustic properties of the object, and parameters of noise at the facility.
The source of the acoustic emission energy is an alternating field of elastic stresses from developing defects. To stimulate the defect of radiation of acoustic waves in the object, as a rule, the mechanical load or the thermal method. In cases where sources of radiation are processes of active corrosion, additional loading is not only not necessary, but rather should be limited to reduce possible interference.
As a structure sensitive method of acoustic emission allows the detection of plastic deformation processes, in fact of destruction and phase transitions. In addition, the method allows to detect the expiration of the working environment (liquid or gas) through the through holes in the object, and friction surfaces. These properties of acoustic emission techniques help to create an adequate system of defects classification and criteria of evaluation of technical condition of the object based on the actual effect of the defect on the strength and serviceability of the object.
This standard serves as a methodical basis of application of acoustic emission method for solving a wide class of engineering problems requiring rapid assessment of the characteristics of the developing field of defects in the material responsible of technical objects.
1 Scope
This standard establishes the procedure for the application of methods of acoustic-emission diagnostics in non-destructive control, destructive control (research), technical diagnosis, technical examination, examination, examination of industrial safety of complex technical systems (technical devices, buildings, constructions and their elements, bridges, building structures, and other objects, the destruction of which damages or impairs the security) to assess their compliance with the industrial safety requirements.
2 Normative references
This standard uses the regulatory references to the following standards:
GOST 12.1.004−91 System safety standards. Fire safety. General requirements
GOST 12.2.003−91 System safety standards. Equipment production. General safety requirements
GOST 12.3.002−75 System safety standards. The process of production. General safety requirements
GOST 27655−88 Acoustic emission. Terms and symbols
Note — When using this standard appropriate to test the effect of reference standards in the information system of General use — on the official website of the Federal Agency for technical regulation and Metrology on the Internet or published annually by the information sign «National standards» published as on January 1 of the current year and related information published monthly indexes published in the current year. If the reference standard is replaced (changed), when using this standard should be guided by replacing (amended) standard. If the reference standard is cancelled without replacement, then the situation in which the given link applies to the extent that does not affect this link.
3 Terms and definitions
This standard applies the terminology according to GOST 27655 as well as the following terms with respective definitions:
3.1 the contractor’s control: the Organization performing acoustic-emission control.
3.2 the customer control: the Organization, ordering the execution of acoustic emission control.
3.3 technique of acoustic-emission diagnostics (control): Technological operations, their parameters for performing acoustic emission diagnostics (monitoring) of a particular object.
3.4 the sensing element of the transducer of acoustic emission: Part of the Converter, where there is a direct conversion of the acoustic signals into electrical.
3.5 technical condition: a Condition that is characterized by a certain time, under certain environmental conditions the values of the parameters, established by the technical documentation for the object.
3.6 diagnostics: definition of the technical state of the object.
3.7 examination of industrial safety: conformity Assessment of the object examination requirements of industrial safety, the result of which is the conclusion.
3.8 the acoustic emission signal: the «Useful» signal, excited by a defect in the process of the AE control and having acoustic nature.
3.9 noise: a Continuous signal that is not associated with the presence of defects in the object and interfere with detection of acoustic emission signals and measurement of their parameters.
3.10 disturbance: Pulse signal having acoustic or electromagnetic nature of origin that is not associated with the presence of defects in the object.
3.11 test: Technical operation that consists in establishing one or more characteristics of the object in accordance with the established procedure.
3.12 threshold of acoustic emission instruments: Setting instrument, expressed in volts, above which values the acoustic emission signals are received and processed.
3.13 limit the sensitivity of the instrument acoustic emission: the Parameter of apparatus of acoustic emission, expressed in volts, corresponding to the RMS value of own thermal (or electronic) noise instrument with a connected transducer AE, shown to the door.
3.14 . working pressure: overpressure that characterizes the performance of the vessel, guaranteed by the manufacturer, or installed by an expert organization on the results of the examination of its technical condition while restoring a technical certificate and specified in the certificate of quality of manufacture of the vessel.
3.15 test pressure: overpressure, which should be the test vessel for strength.
3.16 test pressure: overpressure, which should be the test vessel for strength accompanied by acoustic emission control.
4 Requirements to safety of works
4.1 To conduct AE diagnosis (control) persons who are certified in I, II, III levels of qualification in the field of AE monitoring. Conclusion according to the results of AE monitoring may sign specialists II and III skill levels.
4.2 When working at AE diagnosis (monitoring) the operator should be guided by GOST 12.2.003, GOST 12.3.002 and rules of technical safety for operation of electrical installations, approved by the state energy supervision (Rostekhnadzor).
4.3 Work should be carried out in accordance with the safety requirements set out in the instruction manual of equipment, part of the used measuring instruments.
4.4 the methodology of control a particular element of the technical system must be specified requirements, observance of which is obligatory when working with control objects in the enterprise.
4.5 In the organization of control should comply with fire safety requirements according to GOST 12.1.004 and rules of arrangement and safe operation vessels working under pressure [1].
5 General provisions
The method of acoustic emission (AE) is sensitive to any types of structural changes in a wide frequency range (typically from 10 to 1000 kHz). Equipment capable of detecting not only brittle crack growth, but also the development processes of local plastic deformation, solidification, crystallization, friction, shock, recheobrazovaniya and phase transitions. The main applications that use AE inspection method:
— periodic monitoring of the integrity of the structures;
— control integrity of the structure during the period of crimping;
— monitoring performance of an object when the air test;
monitoring (long-term monitoring with simultaneous processing of results in real time) the integrity of the object;
control of the welding process;
control of wear and contact of the equipment during automatic machining;
control wear and loss of lubrication on the objects;
— detection of missing parts and particles of the equipment;
— detect and control leaks, cavitation and fluid flows in installations;
control of chemical reactions, including corrosion control processes, and also processes liquid-solid transition, phase transformations.
AE method allows to obtain real-time information about the state of the controlled object by recording and analyzing acoustic radiation accompanying the process of restructuring of the solids within the liquids and gases, frictionless surfaces.
5.1 Characteristic features of acoustic emission method, determining its capabilities, settings, and applications
5.1.1 AE method allows the detection and registration in developing or likely to develop defects, which allows to classify the defects by size, and the degree of their danger.
5.1.2 In a production environment AE method allows to identify the increment of cracks in tenths of a millimeter. Extreme sensitivity of acoustic-emission apparatus for current estimates is about 1·10mm
, which corresponds to the identification of the jump in crack length of 1 µm by 1 µm. In a production environment can be identified races of cracks of 0,1−0,3 mm or more.
AE method allows to detect both surface and internal defects in the material of the object.
5.1.3 acoustic emission method is remote. This property provides the execution control of the object using one or more converters of acoustic emission (PAE), is fixedly installed on the surface of the object.
5.1.4 Position and orientation of the object does not affect the detectability of defects.
5.1.5 AE method has fewer constraints associated with the properties and structure of structural materials than other NDT methods.
5.1.6 Restriction of the use of the method in conditions of strong interference is determined by the difficulty of separation of useful AE signals from noise with similar characteristics.
5.1.7 At the beginning of the unstable development of the defect the amplitude and energy of AE signals, and in some cases the activity of acoustic emission sharply increases. The growth factor and AE parameters upon reaching the critical size defect used in the criteria for assessing the risk sources and allows with high probability to detect sources of AE.
5.2 the AE method can be used to monitor objects during their manufacture in the process of acceptance testing at periodical technical examinations, in the process of operation.
5.3 Main objectives of the AE control include:
— detection and recording of acoustic emission source;
— the coordinates of the source;
— determination of type of source;
— risk assessment of sources associated with developing or likely to develop defects.
5.4 the results of the classification of sources in accordance with the criteria of danger take measures for continued safe operation of the facility or its decommissioning. These measures may include the use of alternative methods of non-destructive testing (NDT) to clarify the characteristics of the defect associated with the detected source, the elimination of defect or subsequent control over the behavior of the defect.
5.5 AE method can be used to assess the technical condition of object of control (diagnosis), as well as the speed of development of the defect in early termination of testing or operation of the facility and prevent the destruction of the product.
5.6 there are two types of acoustic emission: continuous and discrete. Registration of continuous acoustic emission indicates the formation of fistulas, through cracks and leaks in the seals, the plugs, valve and flange connections, as well as the processes of plastic deformation. The basis of the discrete or pulsed emission are the mechanisms of wave emission as the processes of moving and abrupt advance of the crack, the destruction of inclusions, stress corrosion, etc. interference of acoustic and electromagnetic origin also have a discrete nature.
5.7 AE monitoring of the technical state of the examined objects is carried out when creating the design of the stress state that initiates in the material object, the work of the AE sources. For this object, as a rule, subjected to a loading force, pressure, temperature field etc. In some cases, the stress state in the test object is created by residual stress. The choice of type of load, the speed changes determines the contractor’s control in accordance with design objects, its working conditions, the nature of the tests.
5.8 it is Recommended to use the scheme and loading conditions, providing creation in a controlled object of the stress state, similar to the stress condition generated workloads.
5.9 the Recommended scheme of application of the AE control method
5.9.1 Conduct AE monitoring of the object. In case of detection of active AE sources in their location they control one of the traditional NDT methods — ultrasonic, radiation, magnetic-particle, liquid penetrant and other stipulated regulatory technical documents. This scheme is recommended for the control of objects in operation. This reduces the volume of traditional NDT methods, as in the case of traditional methods there is a need for scanning across the surface (volume) of the controlled object. In addition, significantly increases the reliability of detection of active (developing or likely to develop) defects.
5.9.2 perform control of the object one or more NDT methods. When it detects an invalid (according to the norms of the applied methods of control) defects or if there are any doubts about the reliability of the applied NDT methods is carried out the control of the object using the acoustic emission method as the referee method. The final decision on admission of the object into operation or repair of the detected defects is taken in this case by results of the conducted AE monitoring.
5.9.3 In the case of the object of the defect identified one of the NDT methods, acoustic emission method is used for tracking the development of this defect. This can be used economical version control system, using a single or malayalee configuration of acoustic emission equipment.
5.9.4 AE method may be used for continuous or periodic monitoring of the structure. In this case, check the AE of defects developing in the object under the influence of workloads, and under the influence of the working environment during operation of the facility.
5.9.5 AE method is recommended when air test object as an accompanying method of enhancing the safety testing. In this case, the purpose of the application of AE monitoring to ensure prevention of catastrophic failure. It is recommended to use AE method as an accompanying method also in any other type of loading, in particular for hydraulic testing of the objects.
5.9.6 the AE method can be used to assess the strength of the object residual life and the question of the possibility of further operation of the facility. Evaluation of the resource should be carried out using a specially developed particular methods agreed upon with the Federal Executive authority, specially authorized in the field of industrial safety relevant objects. In this case the accuracy of the results depends on the amount and quality of a priori information on the model development damage and material state of the controlled object.
5.10 the Order of application of AE method
5.10.1 AE control is carried out in all cases when it is stipulated by the relevant operating regulations, the Rules of arrangement and safe operation of the facilities or the technical documents.
5.10.2 AE control is carried out in all cases when normative and technical documents provided for non-destructive testing methods ultrasonic testing, radiography, MPD, TSD, etc., but for technical reasons, non-destructive testing by these methods is difficult or impossible.
5.10.3 permitted the use of the AE control is listed in 5.10.2 methods of nondestructive testing in coordination with the design organization and/or Federal Executive authority, specially authorized in the field of industrial safety of the corresponding class of objects.
5.11 Prior to the diagnosis of the specific object is recommended to prepare appropriate methodology (technology), and align it with the object’s owner.
5.12 the Method of AE monitoring should satisfy the requirements of Rostekhnadzor to guidance documents for non-destructive testing.
6 requirements for the AE diagnosis tools and equipment
6.1 the means of AE diagnostics and equipment used when performing acoustic-emission diagnostics, are [2], [3]:
— PAE with clamping devices and materials to ensure acoustic coupling with the test object;
— simulators AE signals;
equipment, which includes computing means adapted for receiving, processing, display, storage and registration of AE signals using special software;
— means for loading the controlled object and safety when performing work, and means of communication.
6.2 PAE is used to convert the acoustic signal to an electrical. PAE define key indicators and control settings — sensitivity, immunity to interference, the working frequency range.
6.3 in the control of industrial facilities and building structures it is recommended to use mainly the resonant PAE having a higher sensitivity in comparison with broadband.
6.4 it is allowed to use waveguides, which should be welded or appropriately pressed against the surface of the object of diagnosis to ensure acoustic contact.
6.5 PAE should be fastened to the object with the use of mechanical devices, magnetic holders or with glue. Fixture to install the transducers on the object selected based on structural features. They can be removable (magnetic holders, clamps, collars, etc.) or in the form of fixed brackets.
6.6 With the installation of PAE on the object of control of acoustic contact, the environment must provide effective acoustic communication PAE with the object.
6.7 Contact environment must provide a reliable acoustic contact during the entire test time at temperature of the controlled object.
6.8 as the contact medium it is possible to use machine oil, epoxy resin without hardener, glycerin and other liquid medium.
6.9 surface Roughness of the test object in place of the PAE should be no more than Rz40.
6.10 After installing PAE on the test object are checking their performance using simulators AE.
6.11 as a simulator of AE signals, it is recommended to use a piezoelectric transducer, excited by electrical impulses from the generator. Frequency response simulation of the pulse must match the frequency band of the control system.
6.12 as a simulator of AE signals is also allowed to use the source of the su-Nielsen [fracture of graphite with a diameter of 0.3−0.5 mm, hardness 2T (2N)].
6.13 For the registration of AE in the tests to be applied, the AE instrument corresponding in its configuration and parameters of the controlled object and the control task.
6.14 When testing large objects you should apply the equipment AE in the form of multichannel systems to define the coordinates of signal sources and characteristics of acoustic emission with simultaneous recording of the loading parameters (pressure, temperature, etc.).
6.15 For the control of objects with a simple configuration, or in cases that do not require determining the location of the defects, allowed the use of less complex equipment, i.e. a single-channel device (measuring devices) or multi-channel system in the zone control mode.
6.16 AE system should provide expeditious processing and display of information in real time, as well as the accumulation, documentation, processing, display and output to peripheral devices for documentation accumulated during the test data after the test.
6.17 AE system used to diagnose production facilities shall meet the technical requirements with confirming documents (certificates, certificates of appraisal, etc.).
7. the Order of preparation and holding of acoustic-emission diagnostics
7.1 Preparation for control includes the following main stages:
— analysis of technical documents on the test object;
— coordination with the owner of the equipment control procedures;
— the way locations;
— installation of receivers AE;
— preparation of acoustic emission equipment.
7.2 during the analysis of technical documents conduct review of design and operational documentation, receive information about repairs, history of loading during the last year. Decide on the possibility and type of control: AE control object may be a single, constantly-periodically using portable equipment and permanent with the use of fixed instruments (monitoring). Choose a system of evaluation of inspection results.
7.3 Prior to implementation of control constitute a methodology (technology) control, which accord with the object’s owner.
The owner of the equipment must be coordinated schedule of loading and issues:
— ensure space, power supply, two-way communication;
— prepare the object for inspection;
— safety and comfortable conditions for carrying out the AE control.
The objects to be monitored in their position. After the preparatory work carry out the direct control, starting with the installation of AE transducers to the object.
7.4 installing the PAE
7.4.1 Each receiver should be mounted directly on the surface of the object. In some cases (unavailability of a surface, high temperature, etc.) is to use the waveguides.
7.4.2 the Location of PAE and the number of antenna groups is determined depending on the chosen method of location, size and configuration of the object, parameters of attenuation of sound in the propagation, noise level and required accuracy of determining the coordinates of defects.
7.4.3 To select the distance between the PAE conduct measurement of the attenuation of the signal from the simulator AE and background noise on the object. Select a representative part of the object without the pipes, passages, etc.; set the PAE and move (0.5 m) AE simulators on the line in the direction from the AEO to a distance of 3 m. as the simulator AE recommended scrapping the stylus of the su-Nielsen. It is recommended that the minimum distance from the PAE to the simulator (starting point) of up to 5 cm.
7.4.4 Distance between the PAE when you use GPS navigation locations set so that the AE signal from the simulator were recorded in any location of the controlled area by at least one PAE and had an amplitude not less than specified.
7.4.5 the Maximum distance between the PAE (for zone locations) shall not exceed the distance exceeding the threshold of 1.5. The threshold distance defined as the distance at which the amplitude of the signal from the simulator AE is equal to the threshold voltage.
7.5 Measurement of the speed of sound used to calculate the coordinates of AE sources, is performed as follows:
7.5.1 Simulator AE features out of groups of PAE on the line joining PAE, at a distance of 10−20 cm from one of them.
7.5.2 Conducting multiple measurements (at least five) for different pairs of PAE determine the average distribution time. It and the known distance between the PAE calculate the speed of propagation of the AE signals.
7.6 Preparation of acoustic emission equipment
7.6.1 checking the operability of AE equipment perform after you install the PAE to the controlled object. After testing a second check to confirm the efficiency of the AE system throughout the monitoring period. Check carried out by excitation of an acoustic signal simulator AE within a certain distance of each PAE. As a rule, the distance should be 10−20 cm.
7.6.2 system Parameters are set in accordance with the technical documents on the device and characteristics of the test object obtained in the preliminary work.
7.6.3 In the event of hydraulic testing of the object all work to identify the acoustic characteristics of the structure and configuration of the equipment is performed after complete filling of the object with water.
8 the Procedure of AE diagnostics
8.1 AE diagnostics performed during loading of the object up to a certain pre-selected values and in the process of aging of the load at a given level.
8.2 Loading is performed using special equipment that increase the load — internal (external) pressure, force, weight, temperature, etc.
8.3 Loading performed according to the set schedule, which determines the loading rate, the time exposures of an object under load and load values.
Speed during a constant load reduces the noise and increase the signal-to-noise ratio.
Re-loading provides compliance/violation of the Kaiser effect.
When testing thick-walled structures are recommended to check in AE as on rises and discharges the load to detect an effect of opening and closing of cracks.
An example of a typical load chart is shown in figure 1.
Figure 1 — typical graph of loading
Figure 1 — typical graph of loading
8.4 When loading an object, you must strive to ensure that the stress-strain state (SSS) of the object under test meet the VAT of the object during operation. When analysing the results of monitoring should take into account the difference in VAT.
8.5 the deviation from the standard schedule of loading with reduction report requires justification.
8.6 the Appointment of the maximum load (pressure tests) should be carried out taking into account the material characteristics, the operating conditions of the tested object, temperature and history of loading.
8.7 If the loading of the test object (e.g., pressure vessel) internal pressure maximum value (test pressure) must exceed the maximum operating over the past year, pressure
(operating load according to the technological regulations) of not less than 5% -10%, but not to exceed a test to be determined in the relevant documents.
8.8 Loading sites should be carried out smoothly with the speed at which interference does not occur, exceeding the permitted level.
8.9 Recommended speed of pressure increase are:
8.10 as loading environments can be used water (hydrostatic testing) and gaseous (pneumatic tests) testing environment and working environment of the object.
8.11 In the case of hydrotesting the flow of the biasing fluid is conducted through the nozzle located at the bottom of the object below the liquid level, a fill object.
8.12 during the period of AE tests the level of background noise and acoustic/electromagnetic interference on the test object needs to be mitigated. This should be deleted walking on service platforms, the movement of vehicles, welding and installation work, the work of lifting-transport mechanisms located near the controlled object.
8.13 When testing newly manufactured objects that have not been heat-treatment after welding, acoustic emission, caused by the alignment of the voltage and not connected with development of defects. So spend a mandatory two loading. In the process of increasing the load at the first loading, generally take into account only signals whose amplitude exceeds the threshold level by more than 20 dB, and the signals recorded during the exposure.
8.14 Before the second loading, a load drop after the first cycle should be 50% to 100% of the test load.
8.15 during loading, it is recommended to continuously observe on the screen the overview picture of the AE sources of the test object, the amplitude values of AE signals on all channels from time to time and noise levels (to detect leaks).
8.16, the Test is stopped prematurely in cases where a sharp increase in the activity of sources or the appearance of large-amplitude AE signals to determine the cause.
8.17 In case of detection of a leak test should be stopped to fix it.
9 Rules for processing of acoustic-emission diagnostics
9.1 the collection, processing and analysis of data
9.1.1 In the process of AE monitoring is carried out the registration and rapid data processing.
9.1.2 After the procedure of control is carried out subsequent detailed processing and interpretation of the results.
9.1.3 Processing and analysis of the data determined by the selected system for the classification of AE sources and criteria for evaluation of inspection results.
9.1.4 Before the test is carried out filtering the data to remove information not related to the processes of formation and growth of defects.
9.1.5 Information about the areas of concentration of AE signals recorded and processed using established programs to build graphs provided for each divisional area and the classification of AE sources.
9.2 evaluation of the results of acoustic emission control
9.2.1 After processing of the received signals of acoustic emission inspection results are identified and classified sources of AE.
9.2.2 When deciding on the results of AE monitoring use data, which should contain information about all the AE sources, their classification and details of AE sources, whose parameters exceed the permissible level.
9.2.3 the allowed class of AE source is set by the contractor in preparation for AE monitoring of a concrete object.
9.2.4 the Choice of a system of classification of AE sources and acceptable class of sources is recommended in accordance with the regulations. In accordance with [4] it is recommended to divide the AE sources into four classes.
9.2.5 Upon detection of unacceptable sources should be surveyed these locations using standard NDT methods.
9.2.6 In case of positive evaluation of the technical state of the object according to the results of the AE control or the absence of the registered AE sources the use of additional types of non-destructive control is not required. If the interpretation of the results of AE monitoring, it is advisable to use additional non-destructive testing.
9.2.7 Final assessment of admissibility of detected AE sources when using additional NDT is performed using measured defect parameters on the basis of standard methods of fracture mechanics methods for the calculation of structures for strength and other relevant regulations.
10 the Rules of registration of results of acoustic-emission diagnostics
10.1 Results of AE diagnosis must be contained in the reporting documents — the report Protocol and the conclusion, which is the executor — the organisation that conducted the AE control.
10.2 the report and the conclusion are required reporting documents and may be filed as a separate document. The report additionally decorate according to customer’s requirement.
10.3 report on the results of AE monitoring should include comprehensive data on preparation and carrying out the AE control, as well as information which allows to assess the state of the object and to confirm the level of qualifications of the contractor and the specialists who conducted the monitoring on the basis of which to judge the reliability of the results.
Annex a (mandatory). Classification of AE sources
Appendix A
(required)
Identified and identified AE sources are recommended to be divided into four classes: I, II, III and IV.
To classify AE sources using the parameters of the AE signals emitted by the sources, the loading parameters. Each class of source has its own set of parameters.
As the loading parameter can be pressure (internal or external), stress, time, temperature and other physical quantities, ensuring the creation or conservation of the stress-strain state.
Source class I — corresponds to a non-hazardous defect. Register it to analyze the dynamics of the subsequent development.
Source class II — corresponds to the developing, moderately hazardous defect. His record and monitor the development of the situation in the process of implementation of this control; it is noted in the report and write recommendations for additional monitoring with use of other methods.
Source class III — corresponds to the developing threat to the defect. His record and monitor the development of the situation in the process of implementation of this control; it is noted in the report and write recommendations for additional control by other methods; taking measures to prepare for possible load shedding.
Source IV class — corresponds to the catastrophically dangerous flaw. At check source of class IV performed an immediate load reduction to 0 or the values at which the class of AE source will be reduced to level II or I class. After the load shedding carried out the inspection and, if necessary, other testing methods.
Each higher class of AE source involves the implementation of all actions defined for all sources of lower classes. In case of positive evaluation of the technical state of the object according to the results of the AE control or the absence of the registered AE sources the use of additional types of non-destructive control is not required. If the interpretation of the results of AE monitoring is uncertain, it is recommended to use additional types of non-destructive testing.
Final assessment of admissibility of detected AE sources and displays when using additional NDT is performed using measured defect parameters on the basis of standard methods of fracture mechanics methods for the calculation of structures for strength and other relevant regulations.
The use of specific systems, classification of AE sources and criteria for evaluating the state of the objects depends on mechanical and acoustic emission properties of materials of controlled objects. The choice of the classification system and criteria for evaluating the state of the object is carried out using the following classification system and criteria for assessing the state of the controlled object. Every time you use a particular classification system and the evaluation criteria (and corresponding values of parameters of AE signals, determine classes of sources and evaluation criteria) to justify their use.
The selection is carried out before performing AE control, then the contractor shall make the appropriate hardware configuration and development of required software (if necessary).
The classification of sources is allowed to carry out in accordance with the specialized technology of AE control designed for specific types of objects and approved in the appropriate order.
Bibliography
[1] PB 03−576−03 Rules for design and safe operation of vessels working under pressure. The Gosgortekhnadzor Of Russia
[2] RD 03−299−99 requirements for the acoustic emission equipment used to control hazardous production facilities
[3] RD 03−300−99 requirements for the acoustic emission transducers used for monitoring of hazardous production facilities
[4] PB 03−593−03, Rules of organization and conducting of acoustic-emissive control of vessels, apparatuses, boilers and process piping. The Gosgortekhnadzor Of Russia
The electronic text of the document is verified by:
the official publication of the
M.: STANDARTINFORM, 2007
