The room-temperature mechanical properties of austenitic stainless steel (AISI 304H) internals removed from fluid catalyic cracking unit (FCCU) regenerators were evaluated after 7 to 16 years of service. Mechanical property testing included tensile testing, notched-tensile testing, and charpy V-notch impact testing. This study revealed that significant sigma phase embrittlement of the stainless steel internals had occurred.