The objective of the present work is to investigate the structural soundness of the chimney baffles belonging to the pyrolysis effluent fractionator in a refinery industry and estimate the internal flow distribution pattern quantitatively by using a sealed gamma-ray source. The horizontal scan was followed after the vertical scan for the confirmation of the results. All of the chimney baffles were positioned with no abnormality and internal media were distributed homogeneously. However some deviated area from the normal pattern was found at the lower part of a distributor region.