Abstract: Method of retrofitting catalyst coolers onto FCC regenerators and a cooler configuration specially suited for FCC regenerators uses a large manway or accessway commonly provided on the FCC regenerator to overcome the problems usually associated with finding a suitable space and clearance for the incorporation of a catalyst cooler. The catalyst cooler is added to the regenerator by removing the end cover from an existing manway on an FCC regenerator, extending the nozzle to provide a horizontal nozzle extension, attaching a vertical tube section of a catalyst cooler from the lower side of the nozzle extension and providing a new end closure at an opposite end of the nozzle extension. This method and the cooler apparatus minimizes the amount of welding and design work that must be done on the vessel and its associated piping when adding a catalyst cooler.