AEP’s Crack History: Design Modifications and Lessons Learned on Deaerators and Storage Tanks

There are a total of 85 deaerators and their associated 85 storage tanks on American Electric Power’s (AEP) generating system. Two new replacement deaerators were fabricated and installed in 2007 and 2008, otherwise all the remaining vessels were manufactured from 1943 to 1989. The known manufacturers, fabricators and design basis of these vessels will be presented. A total of 158 leak, crack or flow accelerated corrosion (FAC) events to the vessels pressure boundary have been documented on many of AEP’s deaerators and storage tanks over the last 34 years. A majority of the leak or crack events occur on the super-critical deaerators, and eight vessels are responsible for almost 50% of the documented events. The failure mechanisms and initiation sites will also be discussed. An overview will be provided on several design modifications AEP has implemented on the deaerators over the last 20 years. A “Lessons Learned” for specifying new deaerators will be presented for two new replacement deaerators which were fabricated and installed in 2007 and 2008 on AEP’s system.