Patent Number: 062228978
Section: description

DETAILED DESCRIPTION FIG. 1 is a side view of a scan apparatus 100 positioned about a pipe elbow 102. Apparatus 100 can inspect piping 104 and welds 106 of pipe elbows 102 in a reactor pressure vessel (not shown) of a boiling water reactor (not shown). Apparatus 100 includes a scan head 108 having at least one ultrasonic transducer 110 and a motor 112 that moves scan head 108 along a pipe elbow axis 114. In one embodiment, scan head 108 includes a pair of spaced apart ultrasonic transducers 110. Scan head 108 allows transducers 110 to remain substantially in contact with pipe elbow 102 while scan head 108 traverses pipe elbow 102. Ultrasonic transducers 110 can detect flaws in piping 104 and welds 106 of pipe elbows 102. Transducers 110 are contoured to conform to piping 104. Scan apparatus 100 further includes a scan platform 116 and a pivot arm 118 having a first end 120 and a second end 122. Pivot arm 118 connects scan platform 116 to a pivot pin 124. Specifically, pivot arm second end 122 is connected to scan platform 116 and pivot arm first end 120 is connected to pivot pin 124. Motor 112 pivots pivot arm second end 122 about pivot pin 124. The connection of scan head 108 to pivot arm second end 122 allows ultrasonic transducers 110 to pivot substantially about pivot pin 124 when pivot arm second end 122 pivots about pivot pin 124. FIGS. 2 and 3 are bottom views of scan apparatus 100 including a pair of transducer probes 126 including ultrasonic transducers 110, a connector 128, and a pair of transducer arms 130 each having a first end 132 and a second end 134. Each transducer arm first end 132 is connected to one of transducer probes 126. Connector 128 connects both transducer arm second ends 134 to scan platform 116 which is connected to motor 112. Connector 128, transducer arms 130, and transducer probes 126 form a gimbals that allows ultrasonic transducers 110 to orbit freely about scan platform 116. This freedom of movement of ultrasonic transducers 110 allows ultrasonic transducers 110 to remain in contact with pipe elbow 102 throughout the movement of scan head 108 along pipe elbow 102. Scan platform 116 includes an arcuate cutout 136 having a size and shape to accommodate piping 104. Connector 128 slides along arcuate cutout 136. As connector 128 slides along cutout 136, ultrasonic transducers 110 rotate, at least partially, about a circumference of piping 104. FIG. 4 is a top view of scan apparatus 100 showing connector 128, scan platform 116, and arcuate cutout 136. Connector 128 is positioned at an end of its sliding movement and ultrasonic transducers 110 are rotated fully to their rightmost position. In operation, piping 104 and welds 106 of pipe elbow are inspected using scan apparatus 100 by a method that includes positioning scan head 108 and at least one transducer probe 126 such that at least one ultrasonic transducer 110 is in substantial contact with a pipe elbow surface 138. In one embodiment, there are two transducer probes 126, each holding one ultrasonic transducer 110. Ultrasonic transducers 110 are in substantial contact with pipe elbow surface 138 and are spaced approximately 180 degrees apart. Scan head 108 is then moved axially along pipe elbow 102 by utilizing motor 112 to pivot ultrasonic transducers 110 substantially about pivot pin 124. This axial movement allows transducer probes 126 to travel axially along pipe elbow 102 while ultrasonic transducers 110 remain in substantial contact with pipe elbow surface 138. The step of moving scan head 108 includes pivoting scan head 108 up to about 90 degrees to accommodate a bend in pipe elbow 102 and to enable scan head 108 to access all pipe elbow surfaces 138. During the axial movement, scan head 108 inspects piping 104 and welds 106 in pipe elbow 102 to detect flaws. Scan apparatus 100 moves with a wrist scan motion to enhance the ability of transducer probes 126 to remain in contact with pipe elbow surface 138 during inspection and to enable ultrasonic transducer signals to better penetrate piping 104 and welds 106 of pipe elbow 102. Piping 104 and welds 106 of pipe elbow 102 are inspected as transducer probes 126 move substantially perpendicular to welds 106. FIG. 5 is a side view of a scan apparatus 100 positioned about pipe elbow 102 at a first axial point 140. The axial movement of scan head 108 occurs along pipe elbow 102 in a first direction from first axial point 140 to a second axial point 142. Connector 128 then slides along arcuate cutout 136, incrementally rotating, in a raster type manner, transducer probes 126. Scan head 108 then moves axially along pipe elbow 102 in a second direction from second axial point 142 to first axial point 140. Again, connector 128 slides along cutout 136, incrementally rotating, in a raster type manner, transducer probes 126. Each incremental rotation of transducer probes 126 moves transducer probes 126 about a partial circumference of piping 104. The axial movement of transducer probes 126 and the incremental rotation at the ends of the axial movement are repeated until transducer probes 126 have investigated pipe elbow surface 138 in its entirety. A method of positioning ultrasonic transducer probes 126 to examine piping 104 and welds 106 of pipe elbow 102 includes locating scan apparatus 100 at pipe elbow 102. Since scan apparatus 100 is for use in a reactor pressure vessel of a boiling water reactor, scan apparatus 100 can be deployed in water to a depth of more than about 60 feet. Scan head 108 is then adjusted to allow at least a portion of piping 104 to enter arcuate cutout 136. The next step includes positioning transducer probes 126 substantially in contact with pipe elbow 102, and moving scan head 108 axially along pipe elbow 102. Transducer probes 126 are maintained in substantial contact with pipe elbow 102 throughout the movement of scan head 108 axially along pipe elbow 102. The axial movement of pipe elbow 102 begins at first axial point 140 and moves in a first direction to second axial point 142. Connector 128 is then moved incrementally along arcuate cutout 136 which causes transducer probes 126 and transducer arms 130 to rotate partially about a circumference of piping 102. Scan head 108 is then moved axially along pipe elbow 102 in a second direction from second axial point 142 to first axial point 140. Again, connector 128 is moved incrementally along arcuate cutout 136 which causes transducer probes 126 and transducer arms 130 to rotate partially about the circumference of piping 104. The axial movement of transducer probes 126 and the incremental rotation at the completion of the axial movement are repeated until transducer probes 126 have investigated pipe elbow surface 138 in its entirety. Scan apparatus 100 can be applied to various diameter piping 104 and enables volumetric examination of entire pipe elbows 102. Transducer probes 126 can maintain contact with pipe elbow surface 138 due, at least in part, to the connections between transducer probes 126 and scan platform 116. These connections provide a wrist scan motion that enhances the ability of transducer probes 126 to contour to pipe elbow surface 138 and enables ultrasonic transducer signals to better penetrate pipe elbow surface 138. From the preceding description of various embodiments of the present invention, it is evident that the objects of the invention are attained. Although the invention has been described and illustrated in detail, it is to be clearly understood that the same is intended by way of illustration and example only and is not to be taken by way of limitation. Accordingly, the spirit and scope of the invention are to be limited only by the terms of the appended claims.