T9074-AS-GIB-010/271 Rev 1
shall be noted along the base line of the viewing screen. The screen shall be divided by two horizontal lines at 40 percent (the DRL) and 80 percent (the ARL) of full screen height. 6.6.4.3.4 Procedure. The entire weld volume and heat affected zone (½ inch of base metal, see 6.2.16 and figure 6-2) shall be scanned with shear waves by directing the sound beam to detect both longitudinal and transverse discontinuities as described herein. When full coverage of the weld volume and heat affected zone is not possible due to configuration, accessibility, or base metal discontinuity, and alternate NDT methods (if allowed by the specification) are not practicable, limited coverage shall be approved on a case basis by the authorized representative of NAVSEA and documented in the inspection record (except as allowed in 6.6.4.3.4.1.1). Excess weld reinforcement or temporary obstructions shall be removed when practicable to obtain full coverage. 6.6.4.3.4.1 Longitudinal Discontinuities. The search unit shall be placed on the scanning surface with the sound beam directed perpendicular toward the weld. Continuous scanning shall be performed toward and away from the weld, while oscillating the transducer to the left and right with an included angle of approximately 30 degrees in a radial motion. The sound beam shall traverse the entire inspection zone with a two-directional crossing pattern for full coverage (see figures 6-2, 6-3, 6-5, 6-6, and 6-8). Scanning for longitudinal discontinuities in tee welds shall be performed from the through member surface opposite the attached member when practicable. 6.6.4.3.4.1.1 One Directional Coverage. For typical weld joint designs where full two-directional coverage is not practicable, the UT procedure shall identify the scanning requirements to achieve the maximum amount of two-directional coverage possible with a minimum of one-directional coverage (see figure 6-4). Examples of typical joint designs that cannot be inspected with full two-directional coverage are: butt welds where one member is tapered on both surfaces, tee welds that cannot be scanned from the opposite side of the through member, and corner welds with insufficient scanning surface. Instances of one-direction coverage for joint designs not specified in the procedure shall be approved by the Examiner and documented in the inspection record.
6.6.4.3.4.2 Transverse Discontinuities.
6.6.4.3.4.2.1 Butt and Corner Welds Ground Flush. The search unit shall be placed on the ground weld surface with the sound beam directed parallel to the longitudinal weld axis. Scanning shall be performed in two opposing directions, while oscillating the transducer to the left and right, with an included angle of approximately 30 degrees in a radial motion (see figure 6-8). If the weld width exceeds the width of the transducer, continuous scanning shall be performed. 6.6.4.3.4.2.2 Butt and Corner Welds Not Ground Flush. The search unit shall be placed on the base metal surface at the weld edge with the beam directed approximately 15 degrees toward the weld from the longitudinal weld axis. Scanning shall be performed along both edges of the weld from one surface and in two opposing directions (see figure 6-8). 6.6.4.3.4.2.3 Tee Welds Inspected from the Through Member Surface Opposite the Attached Member (Required Method When Accessible). The search unit shall be placed on the plate surface between the weld toes, with the beam directed parallel to the longitudinal weld axis. Scanning shall be performed in two opposing directions, while oscillating the transducer to the left and right with an included angle of approximately 30 degrees in a radial motion. If the distance between the weld toes exceeds the width of the transducer, continuous scanning shall be performed. 6.6.4.3.4.2.4 Tee Welds Inspected from the Attached Member. The search unit shall be placed on the attached member surface at the weld edge with the beam directed approximately 15 degrees toward the weld from the longitudinal weld axis. Scanning shall be performed along the weld edge from two opposing directions. When accessible, both surfaces of the attached member shall be scanned. In addition, when accessible, scanning shall also be performed on the through member surface on each side of the attached member, and in two opposing directions. 6.6.4.3.4.3 Discontinuity Evaluation. If discontinuities are detected, the sound beam shall be directed to maximize the signal amplitude. To determine the length of a discontinuity, the search unit shall be moved parallel to the discontinuity axis in both directions from the position of maximum signal amplitude. One half the amplitude from a point where the discontinuity signal drops rapidly to the baseline shall be defined as the extremity of the discontinuity. At this point, the scanning surface is marked at the position indicated by the center of the transducer. This shall be repeated to determine the
6-10
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