ASTM_A_577_-_A_577M_-_90_2012.pdf

Designation:A577/A577M90(Reapproved 2012)Standard Specification forUltrasonic Angle-Beam Examination of Steel Plates1This standard is issued under the fixed designation A577/A577M;the number immediately following the designation indicates the yearof original adoption or,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.Scope1.1 This specification2covers an ultrasonic angle-beamprocedure and acceptance standards for the detection of inter-nal discontinuities not laminar in nature and of surface imper-fections in a steel plate.This specification is intended for useonly as a supplement to specifications which provide straight-beam ultrasonic examination.NOTE1An internal discontinuity that is laminar in nature is onewhose principal plane is parallel to the principal plane of the plate.1.2 Individuals performing examinations in accordance withthis specification shall be qualified and certified in accordancewith the requirements of the latest edition of ASNT SNT-TC-1A or an equivalent accepted standard.An equivalentstandard is one which covers the qualification and certificationof ultrasonic nondestructive examination candidates and whichis acceptable to the purchaser.1.3 The values stated in either inch-pound units or SI unitsare to be regarded separately as standard.Within the text,theSI units are shown in brackets.The values stated in eachsystem are not exact equivalents;therefore,each system mustbe used independently of the other.Combining values from thetwo systems may result in nonconformance with the specifi-cation.2.Referenced Documents2.1 ASNT Standards:3SNT-TC-1A Recommended Practice for Personnel Qualifi-cation and Certification in Nondestructive Testing3.Ordering Information3.1 The inquiry and order shall indicate any additions to theprovisions of this specification as prescribed in 11.1.4.Examination Conditions4.1 The examination shall be conducted in an area free ofoperations that interfere with proper performance of theexamination.4.2 The surface of the plate shall be conditioned as neces-sary to provide a clear,easily interpreted trace pattern on thescreen.Any specified identification which is removed toachieve proper surface smoothness shall be restored.5.Apparatus5.1 The amplitude linearity shall be checked by positioningthe transducer over the depth resolution notch in the IIW orsimilar block so that the signal from the notch is approximately30%of the screen height,and the signal from one of the backsurfaces is approximately 60%of the screen height(two timesthe height of the signal from the notch).A curve is then plottedshowing the deviations from the above established 2:1 ratiothat occurs as the amplitude of the signal from the notch israised in increments of one scale division until the backreflection signal reaches full scale,and then is lowered inincrements of one scale division until the notch signal reachesone scale division.At each increment the ratio of the twosignals is determined.The ratios are plotted on the graph at theposition corresponding to the larger signal.Between the limitsof 20%and 80%of the screen height the ratio shall be within10%of 2:1.Instrument settings used during inspection shallnot cause variation outside the 10%limits established above.5.2 The search unit shall be a 45-deg(in steel)angle-beamtype with active transducer length and width dimensions of aminimum of12in.12.5 mm and a maximum of 1 in.25mm.Search units of other sizes and angles may be used foradditional exploration and evaluation.6.Examination Frequency6.1 The ultrasonic frequency selected for the examinationshall be the highest frequency that permits detection of therequired calibration notch,such that the amplitude of theindication yields a signal-to-noise ratio of at least 3:1.7.Calibration Reflector7.1 A calibration notch,the geometry of which has beenagreed upon by the purchaser and the manufacturer,with a1This specification is under the jurisdiction of ASTM Committee A01 on Steel,Stainless Steel and Related Alloys and is the direct responsibility of SubcommitteeA01.11 on Steel Plates for Boilers and Pressure Vessels.Current edition approved March 1,2012.Published March 2012.Originallyapproved in 1967.Last previous edition approved in 2007 as A577/A577M 90(2007).DOI:10.1520/A0577_A0577M-90R12.2For ASME Boiler and Pressure Vessel Code applications,see related Specifi-cation SA-577/SA-577M in Section II of that Code.Available from AmericanSociety of Mechanical Engineers(ASME),ASME International Headquarters,Three Park Ave.,New York,NY 10016-5990,http:/www.asme.org.3Available fromAmerican Society for Nondestructive Testing(ASNT),P.O.Box28518,1711 Arlingate Ln.,Columbus,OH 43228-0518,http:/www.asnt.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1Copyright by ASTM Intl(all rights reserved)