Curved ASME piping calibration blocks are required for ultrasonic examination of welds on pipe of 20 inches (500 mm)diameter and less. These blocks must be sized within certain percentages of pipe diameter and nominalthickness, and many blocks are required to cover the range of common pipe sizes and schedules. As such, it is costprohibitive for an NDT company to purchase a full set of blocks, and also impractical for a manufacturer to stock allsizes. Thus, the scenario may often arise when no compatible block is available, leading to expensive delays andfrustrations for both the service provider and the customer. Using the guidance in ASME Section V (2017), thedesign of compound calibration blocks with stepped intervals on the inside diameter was investigated to reduce thetotal number of blocks required to cover the most common pipe sizes and schedules. During development, CIVAsimulations were used to study the interaction of notches and the effect of multiple reflections off curved inner andouter pipe surfaces. Design features such as reflector positions, section lengths and widths were controlledparametrically, driven by diameter and thickness, to optimize overall size. The culmination of this research resultedin a 3-block set, suitable for conventional and phased array ultrasound, that permits DAC/TCG calibration for pipes3-inch to 20-inch diameter and the majority of pipe schedules. Advantages include reduced overall costs, drasticallyreduced weight totals, and simplified inventory control.

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