A Comparative study of negligible creep curves for rational elevated temperature design

Negligible creep curveによる合理的な高温構造設計に関する検討

安藤 勝訓 ; 磯部 展宏*; 川崎 信史 ; 祐川 正之*; 笠原 直人*

Ando, Masanori; Isobe, Nobuhiro*; Kawasaki, Nobuchika; Sukekawa, Masayuki*; Kasahara, Naoto*

In Japanese elevated temperature standard, creep considering design is required for all ferrite steels applied over 375C and all austenitic stainless steels applied over 425C regardless of the operating time. On the other hands, ASME Sec.III Subsection NH, RCC-MR and R5 provide the additional rules to determine the negligible creep range. In this paper, we recall the backgrounds of the negligible creep criterion which have already been proposed. Then the negligible creep criterion and relating property in each standard were compared. Sensitivities to the difference of criteria and material properties were discussed and concluded that negligible creep curve is strongly dependent on the combination of criteria and material properties. Some evaluations proved that the negligible creep curves in FDS are moderately conservative and practicable.