In a method for testing the integrity of welds at elevated temperatures, a pressurized mixture of a gaseous environmentally safe composition is injected in an area between the inner and outer weld of a terminal flange welded to a tubular pipe section or casing. Adjacent scintillator elements are separated by gaps filled with a composition of white diffuse reflective material, a light absorber, and a castable polymer. The subject configuration addresses installation, calibration, and portability issues that are primary concerns in most vision-based table systems.