ABSTRACT
Bridge pin and hanger assemblies are typically considered as critical elements whose failure may result in partial or complete collapse of the structure. As a result these elements are subjected to a more in-depth examination and testing. Pin and hanger inspection programs typically employ ultrasonic methods to assure that cracks and other discontinuities affecting pin/hanger performance are identified. However, the use of ultrasonic methods can prove difficult considering the complex geometry of typical pin elements which might include keyways, center bore holes, changes in pin diameter, threads, and cotter pin holes. Wear grooves and acoustic coupling further complicate ultrasonic pin testing. These factors and their influence on the success of the pin/hanger inspection are discussed.
Ultimately, the success of a pin/hanger inspection program is dependent upon establishment of a thorough ultrasonic test procedure specific to the bridge under consideration. The key elements of an effective inspection program are highlighted in this paper. The use of straight and various angled beam transducers will be discussed. The influence of signal frequency and transducer diameter on flaw identification will be reviewed. Construction of a model reference pin/hanger can aid in calibration of the ultrasonic inspection procedure.
