Various problems with injection facilities for process additives or wash water are reviewed and appropriate solutions suggested. Topics covered include reasons for injecting process additives or wash water into refinery process streams, process considerations, location and design of injection nozzles, dilution rmethods. and temperature and velocity’ limitations for streams being treated. Corrosion, fouling, and contamination problems downstream of injection points are also covered. Keywords: overhead system corrosion, filming amine corrosion inhibitors, liquid organic neutralizers tbuling by corrosion inhibitors. fouling by neutralizer salts, water washing.