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    IS 7743 (2006): Recommended practice for magnetic particletesting and inspection of steel forgings [MTD 21:Non-Destructive Testing]

  • IS 7743:2006

    Indian Standard

    RECOMMENDED PRACTICE FOR MAGNETICPARTICLE TESTING AND INSPECTION

    OF STEEL FORGINGS

    (First Revision)

    ICS 19.100; 77.140.85

    .!, ,

    0 BIS 2006

    BUREAU OF INDIAN STANDARDSMANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARC

    NEW DELHI 110002

    April 2006 Price Group 3

  • Non-destructive Testing Sectional Committee, MTD 21

    FOREWORD

    This Indian Standard (First Revision) was adopted by the Bureau of Indian Standards, after the draft finalized bythe Non-destructive Testing Sectional Committee had been approved by the Metallurgical Engineering DivisionCouncil.

    This standard was first published in 1975. This standard is intended to be a guide for the manufacturers, inspectingauthorities and purchaser to apply approximate techniques for detecting flaws in ferromagnetic steel forgings.This has now been revised in the light of experience gained in this field.

    In this revision, the following modifications have been carried out:

    a) Scope has been modified by including total length of linear discontinuities in the unit area;

    b) Reference clause has been included;

    c) Requirements of testing personnel (see 4) has been included;

    d) Requirements of surface condition and test equipment have been modified;

    e) Requirements of magnetic inks (see 7.4 and 7.5) have been included;

    t] Requirements of longitudinal magnetization (see 8.1), circular magnetization (see 8.2), yoke method(see 8.3) and locai circuhrmagnetization or prod magnetization (see 8.4) and continuous method (see 10.2)have been modified by including figures; and

    g) Requirements of inspection for non-fluorescent inks have been included.

    This standard is to be read in conjunction with IS 3703 ~2004 Code of practice for magnetic particle flawdetection (second revision).

    For the purpose of deciding whether a~articular requirement of this standard is complied with, the final Wtue,observed or calculated, expressing the result of a test or analysis, shall be rounded off in accordance withIS 2: 1960 Rules for rounding off numerical values (revised). The number of significant places retained in therounded off value should be the same as that of the specified value in this standard.

  • IS 7743:2006

    Indian Standard

    RECOMMENDED PRACTICE FOR MAGNETICPARTICLE TESTING AND INSPECTION

    OF STEEL FORGINGS

    (First Revision)

    1 SCOPE

    1.1 This standard describes the procedure for magneticparticle testing and inspection of ferromagnetic steelforgings.

    1.2 Magnetic particle testing provides for the detectionof cracks and other discontintrities situated at or neart}lesurface in ferromagnetic materials. The sensitivityof the test is maximum for surf~ce discontinuities anddiminishes rapidly with depth below the surface.

    1.3 This standard does not stipulate any requirementfor the acceptance or rejection of forgings on whichflaws have been revealed. This shall be subject tomutual agreement between the contracting parties. Thisagreement may include the fol[owing

    a)

    b)

    c)

    d)

    e)

    A statement specifying that the forgings shallbe subjected to magnetic particle testing andinspect ion in accordance with the standardtogether with any additional requirementsconsidered necessary;

    Locations on the forgings which are subjectedto magnetic particle testing and inspection;

    Stage of manufacture at which the test is tobe conducted, the technique to be used andthe magnetizing field or current strength tobe employed;

    Type of discontinuities to be consideredundesirable; and

    Total length of linear discontinuities in unitarea shall-be reported.

    2 REFERENCES

    The following standards contain provisions whichthrough reference in this text, constitute provisions ofthis standard. At the time of publication, the editionsindicated were valid. All standards are subject to revisionand parties to agreements based on this standard areencouraged to investigate the possibility of applying themost recent editions of the standards indicated below:

    [sNo, Title3415 : 1998 Glossary of terms used in magnetic

    particle flaw detection (secondrevision)3703 :2004 Code of practice for magnetic particle

    flaw detection (second revision)

    [S No. Title

    6410:1991 Magnetic flaw detection inks andpowders (first revision)

    13805:2004 General standard for qualification andcertification ofnon-destructive testingpersonnel (jhst revision)

    3 TERMINOLOGY

    For the purpose of this standard, the definitions givenin IS 3415 shall apply.

    4 PERSONNEL REQUIREMENTS

    Personnel conducting the test in accordance with thispractice shall be qualified and certified as per IS 13805.

    5 SURFACE CONDITION

    5.1 The surface condition of the forging or those partsunder examination shall be such that there is nointerference with the test. All areas to be examhiedshall be free tlom heavy scale, dirt, grease, paint orany other foreign matter, which may interfere with theapplication to test.

    5.2 The methods used for cleaning and preparing thesurfaces for magnetic particle inspection shall not bedetrimental to the material and surface finish of theforgings or to the tested materials.

    5.3 The part shall be demagnetized before examination,if prior operations have produced a residual magneticfield that may interfere with the examination.

    5.4 Magnetic particle examination shall not beperformed with non-conductive coatings.

    6 TESTING EQUIPMENT

    6.1 The testing equipment shall be capable of inducingan adequate magnetic flux in the forging or area offorging under test. Suitable equipment shall beprovided to ensure that the required field strength isobtained. If current flow machines are employed, anammeter shall be incorporated in the output circuit.The ammeter shall have a scale length of 60 mm orgreater, and shall comply with accuracy of +5 percent.The nominal wave form of energizing current shal I beshown on the apparatus. Together with the manner inwhich the current is indicated by the meter of theequipment, for example, peak, r.m.s. mean.

    1

  • IS 7743:2006

    6.2 The high-amperage, low-voltage current requiredin the magnetic testing of forgings may be obtained-from alternating current source, full or half-waverectifiers, a storage battery or a motor generator set.

    6.3 The apparatus and the ancillary equipment shallbe checked at least once in three months by a competentpersonlagency to ensure its continuing efficacy. Arecord of the check shall be kept.

    6.4 A functional test shall be carried out by theoperator before commencing work. The test shall bedesigned to ensure the proper functioning of both theequipment and magnetic medium.

    7 INSPECTION MEDIA

    7.1 General

    For the purpose of this standard, testing materials areclassified in the following groups:

    a)

    b)

    c)

    Group 1 Dry powders, in which themagnetic particles are applied without the useof a carrier fluid.

    Group 2 Magnetic flaw detection inksconsisting essentially of magnetic particles ina carrier fluid.

    Group 3 Fluorescent magnetic inksconsisting of magnetic particles and fluorescentmaterials in a carrier fluid, used in conjunctionwith black light.

    7.2 The testing materials described in 7.1 shall complywith .1S6410.

    NOTE Different carrier fluids may be used in conjunctionwith Group 2 materials and contrast aids may be employedwith Group 1 and Group 2 materials.

    7.3 Magnetic Inks (Group 2 and Group 3)

    Magnetic inks shall be checked at frequent intervalsof two days, if in continuous use in order to ensurethat the suspension satisfies the requirement ofIS6410.Air from a compressor should not be used for agitationbecause of introduction of moisture and the creationof fumes. The magnetic inks shall be discardedand replaced when it become discolored by oil,contaminated by any foreign substance or hasotherwise deteriorated to the extent that properdistribution and concentration of the suspension on theintensity xcharacter or definition of the deposits of themagnetic pat%cles is affected.

    7.4 Magnetic inks shall not be mixed unless they areof the same type-and specification and are supplied bythe same manufacturer.

    7.5 The performance of fluorescent magnetic inks usedin a system where it is re-circulated (that is, pulmped)shall be assessed weekly by comparing its performance

    in revealing known flaws with the performance of freshsample of inks.

    NOTE Bath should be stirred well to bring the settledfluo