Nondestructive Inspection Methods for Railroad Castings

Transportation Technology Center, Inc. (TTCI) has investigated various nondestructive inspection (NDI) methods to determine if they are capable of reliably inspecting side frames, bolsters, knuckles, and couplers. The NDI methods used for this investigation include dry and wet (fluorescent) magnetic particle, liquid penetrant, alcohol wipe, visual, ultrasonic (pulse-echo and phased array), and radiography. Inspection results from all methods were used to determine which methods produced repeatable results. From the initial inspection analysis, TTCI engineers determined that the magnetic particle inspection method is the most capable for detecting defects in railroad castings. Further investigation of the magnetic particle technique was completed to develop reliable inspection methods for use on bolsters, side frames, knuckles, and couplers. Each of the inspection techniques have been used for inspections in the field. Using the results of the field tests, procedures were developed by TTCI and submitted to the Association of American Railroads’ (AAR) Coupling Systems and Truck Castings Committee for review and implementation. The inspection procedures can be used by manufacturers, railroads, and car repair shops. Limitations of the inspection procedures include the amount of time necessary to perform the inspection and the reliability of detecting certain types of defects below the surface of the casting. Although these limitations exist, the procedures developed by TTCI are expected to improve the quality of in-service castings and reduce the number of train partings and derailments due to broken or cracked components.