Case Study on the Acceptance of a Unique Refractory Material in ASME Section VIII

Abstract The use of hot isostatically pressed isotropic pure molybdenum was recently processed through ASME Section VIII. This is a unique material for the manufacture of pressure vessels as pure molybdenum is typically used for applications such as refractory, resistance wire for heating elements and structural thermal barrier components for internal furnaces for hot isostatic presses. There are several specifications for coverage of molybdenum such as ASTM B387, Standard Specification for Molybdenum and Molybdenum Alloy Bar, Rod, and Wire [1], and ASTM B386/B386M, Standard Specification for Molybdenum and Molybdenum Alloy Plate, Sheet, Strip, Foil, and Ribbon [2]. This paper demonstrates the test data needed for ASME approval of this unique material. The paper highlights the gaps in ASME Section II, Part D Appendix 5 and attempts to illustrate the “other information required by the Construction Committee” which may be needed for new materials today. This includes not only the data required by ASME Section II Part D, Appendix 5 [3,4], but also includes additional data which is required for more modern design by analysis techniques, such as elastic-plastic local strain limits and generation of true stress – true strain curves. This paper will also discuss alternative design philosophy approaches which were adopted in lieu of traditional approaches in areas such as fatigue analysis, determination of minimum design metal temperature (MDMT), and alternative approaches to examination and inspection of the material.