Unformatted text preview: SPECIFICATION FOR ULTRASONIC ANGLE-BEAM EXAMINATION OF STEEL PLATES
(Identical with ASTM Speciﬁcation A 577/A 577M-90.) 1. Scope 3. Ordering Information 1.1 This speciﬁcation covers an ultrasonic angle-beam procedure and acceptance standards for the detection of internal discontinuities not laminar in nature and of surface imperfections in a steel plate. This speciﬁcation is intended for use only as a supplement to speciﬁcations which provide straight-beam ultrasonic examination.
NOTE — An internal discontinuity that is laminar in nature is one whose principal plane is parallel to the principal plane of the plate. 3.1 The inquiry and order shall indicate any additions to the provisions of this speciﬁcation as prescribed in 14.1. 4. Examination Conditions 4.1 The examination shall be conducted in an area free of operations that interfere with proper performance of the examination. 4.2 The surface of the plate shall be conditioned as necessary to provide a clear, easily interpreted trace pattern on the screen. Any speciﬁed identiﬁcation which is removed to achieve proper surface smoothness shall be restored. 1.2 Individuals performing examinations in accordance with this speciﬁcation shall be qualiﬁed and certiﬁed in accordance with the requirements of the latest edition of ASNT SNT-TC-1A or an equivalent accepted standard. An equivalent standard is one which covers the qualiﬁcation and certiﬁcation of ultrasonic nondestructive examination candidates and which is acceptable to the purchaser. 1.3 The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the speciﬁcation. 5. Apparatus 2. Referenced Document 2.1 ASNT Standard: SNT-TC-1A
1059 5.1 The amplitude linearity shall be checked by positioning the transducer over the depth resolution notch in the IIW or similar block so that the signal from the notch is approximately 30% of the screen height, and the signal from one of the back surfaces is approximately 60% of the screen height (two times the height of the signal from the notch). A curve is then plotted showing the deviations from the above established 2:1 ratio that occurs as the amplitude of the signal from the notch is raised in increments of one scale division until the back reﬂection signal reaches full scale, and then is lowered in increments of one scale division until the notch signal reaches one scale division. At each increment the ratio of the two signals is determined. The ratios are plotted on the graph at the position corresponding to the larger signal. Between the limits of 20% and 80% of the screen height the COPYRIGHT American Society of Mechanical Engineers Licensed by Information Handling Services SA-577/SA-577M 2001 SECTION II ratio shall be within 10% of 2:1. Instrument settings used during inspection shall not cause variation outside the 10% limits established above. 5.2 The search unit shall be a 45-deg (in steel) angle-beam type with active transducer length and width dimensions of a minimum of 1⁄2 in. [12.5 mm] and a maximum of 1 in. [25 mm]. Search units of other sizes and angles may be used for additional exploration and evaluation. 8. Calibration Procedure 8.1 Plate 2 in. [50 mm] and Under in Thickness: 8.1.1 Place the search unit on the notched surface of the plate with the sound beam directed at the broad side of the notch and position to obtain maximum amplitude from the ﬁrst vee-path indication which is clearly resolved from the initial pulse. Adjust the instrument gain so that this reﬂection amplitude is at least 50 but not more than 75% of full screen height. Record the location and amplitude of this indication on the screen. 8.1.2 Move the search unit away from the notch until the second vee-path indication is obtained. Position the search unit for maximum amplitude and record the indication amplitude. Draw a line between the peaks from the two successive notch indications on the screen. This line is the distance amplitude curve (DAC) for this material and shall be a 100% reference line for reporting indication amplitudes. 8.2 Plate Over 2 to 6 in. [50 to 150 mm] Inclusive in Thickness: 6. Examination Frequency 6.1 The ultrasonic frequency selected for the examination shall be the highest frequency that permits detection of the required calibration notch, such that the amplitude of the indication yields a signal-to-noise ratio of at least 3:1. 7. Calibration Reﬂector 7.1 A calibration notch, the geometry of which has been agreed upon by the purchaser and the manufacturer, with a depth of 3% of the plate thickness, shall be used to calibrate the ultrasonic examination. The notch shall be at least 1 in. [25 mm] long. 7.2 Insert the notch or notches on the surface of the plate so that they are perpendicular to the long axis at a distance of 2 in. [50 mm] or more from the short edge of the plate. Locate the notch not less than 2 in. [50 mm] from the long edges of the plate. 7.3 When the notch cannot be inserted in the plate to be tested, it may be placed in a calibration plate of ultrasonically similar material. The calibration plate will be considered ultrasonically similar if the height of the ﬁrst back reﬂection through it is within 25% of that through the plate to be tested at the same instrument calibration. The calibration plate thickness shall be within 1 in. [25 mm] of the thickness of plates to be tested, for plates of 2 in. [50 mm] thickness and greater and within 10% of plates whose thickness is less than 2 in. [50 mm]. 7.4 For plate thicknesses greater than 2 in. [50 mm], insert a second calibration notch as described in 7.2, on the opposite side of the plate.
1060 8.2.1 Place the search unit on the test surface aimed at the broad side of the notch on the opposite surface of the plate. Position the search unit to obtain a maximum one-half vee-path indication amplitude. Adjust the instrument gain so that this amplitude is at least 50% but not more than 80% of full screen height. Record the location and amplitude on the screen. Without adjusting the instrument settings, repeat this procedure for the 11⁄2 vee-path indication. 8.2.2 Without adjusting the instrument settings, reposition the search unit to obtain a maximum full vee-path indication from the notch on the test surface. Record the location and amplitude on the screen. 8.2.3 Draw a line on the screen connecting the points established in 8.2.1 and 8.2.2. This curve shall be a DAC for reporting indication amplitudes. 8.3 Plate over 6 in. [150 mm] in Thickness: 8.3.1 Place the search unit on the test surface aimed at the broad side of the notch on the opposite surface of the plate. Position the search unit to obtain a maximum one-half vee-path indication amplitude. Adjust the instrument gain so that this amplitude is at least 50% but not more than 80% of full screen height. Record the location and amplitude on the screen. 8.3.2 Without adjusting the instrument settings, reposition the search unit to obtain a maximum full COPYRIGHT American Society of Mechanical Engineers Licensed by Information Handling Services PART A — FERROUS MATERIAL SPECIFICATIONS SA-577/SA-577M vee-path indication from the notch on the test surface. Record the location and amplitude on the screen. 8.3.3 Draw a line on the screen connecting the points established in 8.3.1 and 8.3.2. This line shall be a DAC for reporting indication amplitudes. 11. Rehearing 11.1 The manufacturer reserves the right to discuss unacceptable ultrasonically examined plate with the purchaser with the object of possible repair of the ultrasonically indicated discontinuity before rejection of the plate. 9. Examination Procedure 12. Inspection 9.1 Scan one major surface of the plate on grid lines perpendicular and parallel to the major rolling direction. Grid lines shall be on 9 in. [225 mm] centers. Use a suitable couplant such as water, oil, or glycerin. Scan by placing the search unit near one edge with the ultrasonic beam directed toward the same edge and move the search unit along the grid line in a direction perpendicular to the edge to a location two plate thicknesses beyond the plate center. Repeat this scanning procedure on all grid lines from each of the four edges. 9.2 Measure grid lines from the center or one corner of the plate. 9.3 Position the search unit to obtain a maximum indication amplitude from each observed discontinuity. 9.4 For each discontinuity indication that equals or exceeds the DAC, record the location and length, and the amplitude to the nearest 25%. No indication with an amplitude less than the DAC shall be recorded. 9.5 At each recorded discontinuity location, conduct a 100% examination of the mass under a 9 in. [225 mm] square which has the recorded discontinuity position at its center. Conduct the examination in directions perpendicular and parallel to the major rolling direction. 12.1 The purchaser’s representative shall have access, at all times while work on the contract of the purchaser is being performed, to all parts of the manufacturer’s works that concern the ultrasonic examination of the material ordered. The manufacturer shall afford the representative all reasonable facilities to satisfy him that the material is being furnished in accordance with this speciﬁcation. All examinations and veriﬁcations shall be so conducted as not to interfere unnecessarily with the manufacturer’s operations. 13. Marking 13.1 Plates accepted in accordance with this speciﬁcation shall be identiﬁed by metal stamping or stencilling “UT A 577” in one corner of the plate, at a location within 6 in. [150 mm] of the heat number. 14. Report 14.1 Unless otherwise agreed upon between the purchaser and manufacturer, the manufacturer shall report the following data: 14.1.1 Plate identity including pin-pointed recordable indication locations, lengths, and amplitudes. 10. Acceptance Standard 10.1 Any discontinuity indication that equals or exceeds the DAC shall be considered unacceptable unless additional exploration by the longitudinal method indicates it is laminar in nature. 14.1.2 Examination parameters, including: couplant; search unit type, angle, frequency, and size; instrument make, model, and serial number; and calibration plate description. 14.1.3 Date of examination and name of operator. 1061 COPYRIGHT American Society of Mechanical Engineers Licensed by Information Handling Services ...
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This note was uploaded on 10/04/2010 for the course ENGINEERS 22453175 taught by Professor Heydari during the Spring '08 term at Miami University.
- Spring '08