ASME STP-NU-013 : 2008

Foreword
Abstract
PART 1 - IMPROVEMENT OF ASME NH FOR
         GRADE 91 (NEGLIGIBLE CREEP)
1 INTRODUCTION
2 NEGLIGIBLE CREEP CRITERIA
3 APPLICATION TO MOD. 9CR-1MO STEEL
4 TENTATIVE IMPROVEMENT IN THE
  CORRELATION FOR MOD. 9CR-1MO AT
  MODERATE TEMPERATURES
5 DISCUSSION
6 CONCLUSIONS
References
PART 2 - IMPROVEMENT OF ASME NH FOR
         GRADE 91 (CREEP-FATIGUE)
1 INTRODUCTION
2 MOD 9CR-1MO STEEL
3 CREEP-FATIGUE PROCEDURES IN
  THE NUCLEAR CODES
4 PRESENTATION OF THE CREEP-FATIGUE
  TESTS AVAILABLE ON MOD 9CR-1 MO
5 DISTINCTIVE FEATURES OF CREEP
  FATIGUE OF MOD 9Cr-1 MO
6 EVALUATION OF EXISTING PROCEDURES
7 CONCLUSIONS
References
PART 3 - PROPOSED TEST PROGRAM TO ASSESS
         NEGLIGIBLE CREEP CONDITIONS OF
         MODIFIED 9CR-1MO
1 INTRODUCTION
2 MATERIAL
3 CREEP TESTS
4 CREEP FATIGUE TESTS
5 CONCLUSIONS
References
PART 4 - PROPOSED TEST PROGRAM TO
         VALIDATE CREEP-FATIGUE PROCEDURES
         FOR MODIFIED 9CR-1MO
1 INTRODUCTION
2 MATERIAL
3 SUMMARY OF CREEP-FATIGUE
  TESTS RESULTS
4 PURPOSE OF FUTURE TEST PROGRAM
5 PROPOSED TEST PROGRAM
6 CONCLUSIONS
References
Acknowledgements
Abbreviations And Acronyms

This report provides recommendations for improvement of ASME Section III-NH, Components in Elevated Temperature Service, for Grade 91 in the areas of negligible creep and creep-fatigue. The report is separated into the following four parts. Part I - Examines the current approaches available to define negligible creep and checks their applicability to Grade 91 steel. The work is based on material data available in France and the U.S. Part II - Compares Subsection NH and RCC-MR creep-fatigue procedures. Comparisons are performed on cases defined on the basis of experimental test results available from Japan, France and the U.S. on Grade 91 steel. Particular attention was paid to the definition of safety factors and creep-fatigue damage envelope. Improvements to existing procedures are recommended. Part III - Aimed at defining tests necessary to validate negligible creep conditions for Mod 9Cr-1 Mo material. Part IV - Completes the work performed in Part II which, on the basis of creep-fatigue tests results available from Japan, Europe and the US, compared creep-fatigue procedures of ASME Subsection NH and RCC-MR Subsection RB.