Deformation and Crack Analysis of Reaction Furnace for Ammonia Decomposition

The deformation in furnace body and a lot of cracks in welding line were observed.The deformation and cracks of reaction furnace were analyzed by metallographic test,chemical analysis,fracture observation,creep calculation,etc.There existed large numbers of brittle phases in body and especially in welding line in use under high temperature condition,resulting in increasing brittleness.The calculation indicated that the factual stress approached the creep limit stress of 316S at 800-850 ℃,which induced the creep and deformation of body.The cracks propagated in welding line because of increasing stress and the welding line couldn’t synchro-deform at the same speed as body.As a result,the cracks gradually expanded and led to early failure of furnace.