外面応力腐食割れ(ESCC)の感受性の評価

抄録

There are three elements, namely environment, material, and stress, as susceptibility conditions of damage patterns of the equipment. Susceptibility of damage can be mainly evaluated by temperature parameter. Damage patterns of the equipment become apparent in low temperature region, normal temperature region and high temperature region along with aging degradation, and these damage patterns cause leakage during operation. In particular, damage appears prominently under low temperature environment. Among them, it is difficult to extract susceptibility to external stress corrosion cracking External stress corrosion cracking of austenitic stainless steel is generated when grain boundary Cr depletion layer (sensitization) of weld heat affected zone (HAZ) occurs due to rainwater retention and sea salt particles. However, sensitization does not occur in all of HAZ. Occurrence of sensitization differs in every part. Therefore, this paper describes in detail findings obtained from survey results on the ESCC in a chemical plant.