Gulf Petrochemical Industries Co. complex has two atmospheric pressure ammonia storage tanks, each of 20,000 MT capacity. The tanks have been in operation since 1985. European Fertilizer Manufacturer's Association (EFMA) guidelines for "Ammonia Tanks Inspection" were adopted to set the frequency for inspection of the tanks. One ammonia tank was decommissioned in 2004 for internal inspection and replacement of insulation blocks. The decommissioning, inspection, and recommissioning project duration was 5 months. Based on this experience, the second tank was successfully decommissioned and inspected in the year 2006 in just 4 months. This article describes the methodology followed for the inspection project of the tanks along with details of decommissioning and recommissioning. (C) 2008 American Institute of Chemical Engineers Process Saf Prog 28: 45-59, 2009