Abstract: Gamma scanning and neutron backscatter techniques, which are widely used in petrochemical plants were briefly introduced. The fundamental of them was explained and the major applications of them in the petrochemical plants were given. Emphasis was placed on the application of gamma scanning in tower operation. Specific examples of their industrial application in recent years were listed, including the level detection of an industrial gas/liquid separator and a hydrogenation reactor by the technique of neutron backscatter. The industrial applications showed that radioactive techniques can play a key role in troubleshooting, optimization and predictive maintenance of the petrochemical devices.