1、BRITISH STANDARDBS ISO 24497-3:2007Non-destructive testing Metal magnetic memory Part 3: Inspection of welded jointsICS 25.160.40g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51
2、g60g53g44g42g43g55g3g47g36g58BS ISO 24497-3:2007This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 December 2007 BSI 2007ISBN 978 0 580 55672 2National forewordThis British Standard is the UK implementation of ISO 24497-3:2007.The UK particip
3、ation in its preparation was entrusted to Technical Committee WEE/46, Non-destructive testing.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsib
4、le for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations.Amendments issued since publicationAmd. No. Date CommentsReference numberISO 24497-3:2007(E)INTERNATIONAL STANDARD ISO24497-3First edition2007-11-01Non-destructive testing Metal magnetic m
5、emory Part 3: Inspection of welded joints Essais non destructifs Mmoire magntique des mtaux Partie 3: Examen des assemblages souds BS ISO 24497-3:2007ii iiiContents Page Foreword iv 1 Scope . 1 2 Basic principles 1 3 Inspection conditions. 2 4 Inspection devices 2 5 Inspection planning 3 6 Inspectio
6、n procedure . 4 7 Processing of results . 5 Annex A (normative) Inspection report 7 Annex B (informative) Example of stress concentration zones defined by a device with digital indication of the magnetic field intensity. 9 Annex C (informative) An example of stress concentration zones defined by the
7、 device having recorder and scanner . 11 BS ISO 24497-3:2007iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical com
8、mittees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
9、 International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft Internatio
10、nal Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be t
11、he subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 24497-3 was prepared by the International Institute of Welding, Commission V, Quality control and quality assurance of welded products, recognized as an international standardizing body
12、in the field of welding in accordance with Council Resolution 42/1999. Requests for official interpretations of any aspect of this part of ISO 24497 should be directed to the ISO Central Secretariat, who will forward them to the IIW Secretariat for an official response. ISO 24497 consists of the fol
13、lowing parts, under the general title Non-destructive testing Metal magnetic memory: Part 1: Vocabulary Part 2: General requirements Part 3: Inspection of welded joints BS ISO 24497-3:20071Non-destructive testing Metal magnetic memory Part 3: Inspection of welded joints 1 Scope This part of ISO 2449
14、7 specifies the general requirements for the application of the metal magnetic memory inspection method (MMM inspection) as a non-destructive testing method for quality assurance of welded joints of pressurized components. This part of ISO 24497 may be applied to welded joints in any type of product
15、s, pipelines, vessels, equipment, and metal constructions, as agreed with the purchaser. The terms and definitions for the process are contained in ISO 24497-1, and the general requirements of the process are in ISO 24497-2. 2 Basic principles 2.1 inspection is based on measurement and analysis of t
16、he distribution of self-magnetic-leakage fields (SMLF) in the material of welded joints reflecting their technological history. Natural magnetization, induced during the welding process in the Earths magnetic field, is used for the inspection. 2.2 inspection permits the detection of mechanical stres
17、s concentration zones (SCZ) and gives recommendations for additional non-destructive inspections in critical zones of vessels, pipelines, equipment, and construction welded joints. 2.3 inspection is complementary in its capability to other well-known non-destructive testing methods (ultrasonic inspe
18、ction, magnetic particle inspection, liquid penetrant inspection, and hardness testing). 2.4 inspection allows the testing of welded joints of any size and configuration (butt, tee, fillet, lap, edge, intermittent, etc.) regardless of weld material thickness on all types of ferromagnetic and austeni
19、tic steels and alloys, as well as on cast irons. 2.5 inspection may be carried out on the original weld after construction, during operation, or after repair. 2.6 The following conditions can be found during MMM inspection: residual stress concentration zones caused by welding, and their distributio
20、n along the welded joint; zones of probable location of all types of micro- and macro-defects (pores, slag inclusions, discontinuities, cracks, ruptures). Defect classification by magnetic parameters is carried out following special testing techniques for a specific welded joint. BS ISO 24497-3:2007
21、2 2.7 MMM inspection can be used for inspection of the following: the degree of quality degradation of welds by defects, and presence of developing defects; the quality of welded joints at time of certification, choice, and optimization of welding technology. 2.8 The MMM inspection temperature range
22、 is from 20 C to +60 , limited only by the conditions of the operators and inspection tools normal operation. 2.9 Following MMM inspection, conventional non-destructive testing methods are applied in detected zones of maximal stress concentration and probable location of micro- and macro-defects. 3
23、Inspection conditions 3.1 Structures and components as inspection objects (IO) may be inspected using MMM both while operating under load and after releasing the working load. 3.2 No special surface preparation is required. It is recommended to remove insulation. In individual cases non-magnetic ins
24、ulation is allowed during inspection. The maximum permissible insulation layer thickness shall be determined experimentally. 3.3 The permissible range of material thickness is defined by the descriptions of the techniques for specific inspection applications. 3.4 The limiting factors for MMM applica
25、tion are the following: the presence of artificial material magnetization; the presence of a foreign ferromagnetic product near the IO; the presence of an external magnetic field or an electric welding current flow closer than 1 m to the IO. 3.5 Acoustic noise or mechanical vibrations close to and a
26、t the IO do not influence the inspection results. 4 Inspection devices 4.1 For inspection of equipment using the MMM, specialized magnetometric devices are used. The standard procedure for the definition of stress concentration zones (SCZ) is described in the manual of the devices. 4.2 The principle
27、 of the operation of the specified devices is based on the registration of induced electrical voltage impulses in the flux-gate sensor coil, when this sensor is placed in the self-magnetic-leakage field (SMLF) in the near-surface area of the IO. Flux-gate sensors or other types, such as field meters
28、 or gradiometers, may be used as SMLF intensity measuring sensors. 4.3 The devices shall have a display for the graphic documentation of the used inspection parameters, a recording device with a microprocessor, a memory unit, and scanning devices realized by specialized sensors. The device shall be
29、able to transfer the information to the computer, in order to produce inspection reports. The software for the processing of computerized inspection results should be provided with the device. BS ISO 24497-3:200734.4 The specialized sensors shall be provided with the device. The individual sensor ty
30、pe to use is defined by the MMM technique and the requirements of the IO. The sensor should have not less than two channels: the measuring channel and a channel for the registration of the Earths external magnetic field. With the sensors, an electronic module for the amplification of the measured fi
31、eld and a sensor for measuring the inspected scan path length shall be supplied. 4.5 The admissible error of magnetic field intensity measurements is defined in the description of the individual techniques depending on the IO. 4.6 The devices shall have the following metrological characteristics: Th
32、e relative error of the measured magnetic field for each measurement channel should not exceed 5 %. The relative error of the measured scan path length should not exceed 5 %. The measurement range of the devices should be not less 1 000 A/m. The minimal scanning step (distance between two adjacent s
33、canning points of the inspection) is 1 mm. The level of electronic noise caused by the processor and the microelectronic devices should not exceed 5 A/m. 4.7 The device shall have the possibility to define logfiles according to the user manual. 5 Inspection planning 5.1 Inspection planning includes
34、the following basic stages: the analysis of the technical documentation of the object to be inspected and preparation of a checklist for the inspection; the adjustment and calibration of the devices and sensors, following the instructions given in the user manual; the selection of the individual sen
35、sors and the type of the inspection device; the segmentation of the IO into separate inspection areas and inspection units, according to the design features of the component and their documentation in an inspection logfile. 5.2 The technical documentation for the IO shall include the following: a de
36、scription of the steel grade; a description of the operation modes of the objects and failure modes; a description of the design features of the component and the locations of welded joints. BS ISO 24497-3:20074 6 Inspection procedure 6.1 Inspection of welded joints using a device with a digital ind
37、ication of the magnetic field intensity The sequence of scanning by the sensor of the device for the evaluation of several types of welded joints is shown in Figure 1. Dimensions in millimetres a) Moving the sensor along the welded joint b) Moving the sensor perpendicular to the welded joint Key 1,
38、2, 3 inspection zones WM weld material HAZ heat-affected zone of welded joint PM parent metal Figure 1 Scanning sequence by the sensor for the evaluation of several types of welded joints according to the residual magnetization of the material The flux-gate sensor is placed perpendicular to the insp
39、ection surface and is moved by the operator manually and sequentially along the entire perimeter of a weld (separately along a weld material and along the heat-affected zones on both sides of the weld) and then perpendicular to the weld, with a distance from the edge of the weld of 30 mm to 50 mm on
40、 both sides of the parent material of a pipe. The second operator records the inspection data in a logbook: magnetic field intensity (Hp, A/m) with plus or minus amplitudes. The discontinuous change of the sign and value of the Hpfield indicates the concentration of residual stresses along the Hp= 0
41、 line for a specific segment of the welded joint. These segments have to be marked by chalk or paint. BS ISO 24497-3:200756.2 Inspection of welded joints using a device having display, recorder, and scanner The inspection scheme for a butt-welded joint is shown in Figure 2. The inspection is carried
42、 out using a scanner consisting of four flux-gate transducers 1, 2, 3, 4 and a length-measuring device, built into the case of a trolley programmed to measure the length of an inspected inspection segment simultaneously with the measurement of values of magnetic field intensity, Hp. As shown in Figu
43、re 2, during inspection, transducers 1 and 3 are arranged in the heat-affected zones from both sides of a weld, and the transducer 2 is centred between them. Before the beginning of the inspection for each measurement channel, the scanning step of measurement of the Hpfield (value S in the set-up me
44、nu of the device) is set. The step of measurement is S or the distance between two adjacent scanning points of inspection, lK, for each measurement channel. This value should not exceed the wall thickness of the material joined by the weld. Key 1, 2, 3 flux-gate transducers of the scanner for the Hp
45、field recording on a weld surface 4 flux-gate transducer for adjustment from an external magnetic field Hp5 wheels of a drive of a length-meter lbbase distance between adjacent transducers 1, 2, and 3 Figure 2 Inspection of butt-welded joints of pipes using a four-channel sensor of the device The ba
46、se distance lbbetween adjacent transducers 1, 2, and 3 is set in accordance with the dimensions of the welded joint and is recorded in the device memory after measurements (value b in the set-up menu of the device). 7 Processing of results 7.1 Using the results of MMM inspection, the following param
47、eters are determined. The magnetic field gradient for each measurement channel pinK,HKl=where lKis the distance between two adjacent points of the inspection. BS ISO 24497-3:20076 The magnetic field gradient between measurement channels pb, inb,HKl=where lbis the basic distance between measurement c
48、hannels. Median and maximum values Kmed, inand Kmax, infor each measurement channel and the basic distance between measurement channels. The magnetic parameter, m, describing a degree of a non-uniformity of the stress-strain state (SSS) and deformability of material in the stress concentration zone:
49、 max, inmed, inKmK= (m is in the range 1,05 to 3,0 and more, depending on the welded joint quality). All indicated magnetic parameters are determined using software supplied with the instrument. 7.2 The areas most susceptible to development of damage are the segments of a weld, on which the maximum Hpfield values of different polarity between measurement channels (maximum value of Kb, in) are indicated and also the maximum value of the field gradient Kmax, inon any of the me
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