L51504 Investigation of Real-Time Radiographic Methods for Use in Pipeline Weld Inspection

Conventional radiography has been the accepted nondestructive examination (NDT) method used for many years to either “accept” or “reject” a field weld in the pipeline industry. The cost of conventional radiography, however, increasingly has become a major concern in the cost effectiveness of laying new pipelines. The contributing factors to the high cost of conventional radiography are the costs of film and of the chemicals and manpower used to develop the film. Over the last few years, a newer approach to performing radiographic testing has been perfected. Called “real-time radiography,” it uses radiographic sources with an optical imaging system. It has been developed now to the point that the sensitivity, contrast, and resolution of these imaging systems can be used to detect variations in material density equivalent to defects of interest in pipeline welds.

The first objective of Phase 1 was to investigate existing real-time radiographic systems and system components in terms of their application to inspection of field-produced girth welds in steel pipelines. The second objective was to recommend a real-time system (either existing as a whole unit or comprised of several key subsystems) to be used for a field demonstration during Phase 2 of the program. The incentive, or goal, for this two-phase program is to introduce real-time radiography to the pipeline industry as a faster and overall more cost effective alternative NDE method compared to conventional film radiography. In addition, real-time radiography would provide a means to interpret the condition of a weld soon after completion while the welding team is still in the near vicinity of the inspected weld. This would permit immediate repair, if necessary, which would greatly reduce cost.