A round robin test series was conducted to assess the imperfection/flaw sizing of ultrasonic time of flight (UTOF) technology for application to oil country tubular goods (OCTG). A total of eight NDE technologists participated. Testing was done using flat plate specimens with a total of 12 electrostatic discharge machined (EDM) notches. The round robin objective was to determine the feasibility of using UTOF methods in the prove up stage of OCTG production to obtain crack size data in support of life prediction.Sizing results were essentially best case, i.e., flat plate specimens with controlled EDM notch flaws. Overall comparisons between actual and measured notch depths were very encouraging, with average sizing deviations under 5 mils for the better technologists. Correlation between plate thickness and measurement deviation showed the expected result that time of flight diffraction may have limits for thin wall pipe. Little or no correlation was observed between notch depth and measured deviations. Flat plate testing with controlled flaws appears to be a viable means of initial selection and feasibility assessment of an NDE approach for OCTG, but actual defect testing will be required to finalize method selection and optimal OCTG procedures.