T9074-AS-GIB-010/271 Rev 1
6.6.4.4.2.1 Inspection Zone. The depth of the inspection zone shall be from the through member surface into the through member ¼ inch inclusive. The depth of the inspection zone shall be expanded to determine the maximum depth of discontinuities extending into the through member. The width of the inspection zone shall be limited to the thickness of the attachment member plus the fillet reinforcement (see figures 6-10 and 6-11). If the particular configuration to be inspected is not discussed in this document, a method should be used which assures that complete coverage of the inspection zone will be obtained. 6.6.4.4.2.2 Search Units. The maximum dimension of the transducer’s active element shall not be greater than 1 inch. The frequency shall not be less than 2.0 MHz. The transducers used for shear wave tests shall be affixed to suitable wedges designed to induce shear waves in the material under test at a specific angle from 45 to and including 60 degrees. Supplemental beam angles may be used for the detection and evaluation of discontinuities. 6.6.4.4.2.3 Calibration. The instrument range and delay controls shall be adjusted to discriminate and indicate signals on the viewing screen from the depth of the inspection zone. The instrument gain shall be adjusted to peak the signal from the calibration hole that is not greater than plus or minus ¼ inch from the through member thickness to not less than 80 percent of full screen height. The corresponding depth and location of the peaked signals from the calibration standard shall be noted along the base line of the viewing screen. The screen shall be divided by two horizontal lines at 20 percent (the DRL) and 80 percent (the ARL) of full screen height. 6.6.4.4.2.4 Procedure. Shear wave scanning for discontinuities into the through member in any tee weld configuration shall be performed as shown on figure 6-11 whenever the surface opposite the attachment member is accessible. If the surface opposite the attachment member is not accessible and the side adjacent is accessible, the scanning shall be accomplished as shown on figure 6-10; however, there shall be no attachments in the area where the reflection of the wave occurs. The entire inspection zone shall be scanned in two directions, as illustrated on figure 6-10 and figure 6-11. Indications from the surface of the far fillet shall be disregarded. The shear wave search unit shall be placed on the scanning surface and directed toward the particular inspection zone. The search unit shall be oscillated to the left and right with an included angle of approximately 30 degrees in a radial motion while scanning perpendicularly toward the inspection zone. Continuous scanning shall be used. When any indication is noted from a discontinuity within the inspection zone, the sound beam shall be directed to maximize the indication. The length, depth, position, and maximum signal amplitude shall be determined and reported for discontinuities yielding a signal amplitude equal to, or exceeding, the DRL. The length of discontinuities shall be determined as specified in 6.6.4.4.1.3. The recorded depth of a discontinuity shall be the minimum and maximum perpendicular distances of the discontinuity from the through member surface. This should be determined in the following manner: a. Maximize the indication from the discontinuity. b. For discontinuities extending to a surface, move the search unit toward the discontinuity and record the depth from the viewing screen at which the indication begins to drop rapidly toward the base line. c. In addition, for discontinuities that do not extend to the surface, repeat the above and move the search unit away from the discontinuity to determine the other limit of depth at the point where the indication again begins to drop rapidly toward the base line.
6-12
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