ASME STP-PT-080

Abstract

Scope: FOREWORD The purpose of this project is to develop isochronous stress-strain curves and external pressure charts in the creep regime for 9Cr-1Mo-V steel taking into consideration updated information and data available in the literature. The temperature range is 800oF to 1200oF. The time range is Hot Tensile up to 300,000 hours. The project is divided into four parts in order to accomplish the required tasks. PART 1. In this part creep model equations are generated for 9Cr-1Mo-V steel. The equations and applicable current data are gathered from many sources as detailed and explained in this part. PART 2. The physical data of Part 1 are converted in this part to equation form and combined with the stress-strain creep model equations in order to have a unified system usable for generating isochronous curves. Examples are given to demonstrate the feasibility of generating isochronous curves directly from equations for any temperature and time within the scope of this project. Isochronous stress-strain charts are also drawn for reference purposes. PART 3. In this part equations are developed for the purpose of constructing external pressure curves and charts for the 9Cr-1Mo-V steel. These curves and charts, which are constructed from equations for various temperatures and times, are verified for accuracy against charts drawn directly from the isochronous curves by the graphical and finite difference methods. PART 4. The equations derived in this part for designing components in the creep regime are applicable to all materials. They are included in this report to show the integration of design equations with equations used to construct external pressure curves in the creep range. Reference is made throughout this document to the ASME BPVC Section III-NH Code. Presently all of the current contents in III-NH are also in Section III, Division 5 of the ASME BPV Code for nuclear class NB applications. However, it should be noted that Section III-NH is slated for elimination in the middle of 2017. At that time the material tables and charts in III-NH will be transferred to the ASME BPV Code Section II-D. Similarly, a revised text of the rules in III-NH will appear in ASME Code Case 2843 for Section VIII applications. The authors extend their thanks to various members of ASME BPV I, II, III, and VIII Committees for their support of this project. It is hoped that the results generated in this report will benefit all of these codes. Special thanks are given to Dr. Kevin Jawad for obtaining the derivatives of some of the complicated equations in PART 3 of the report. Thanks are also given to reviewers Dr. Peter Carter, Mr. Don Kurle, Mr. Benjamin Hantz, Dr. John Grubb, and Mr. Robert Mikitka for their thoughtful comments and to Ms. Colleen O’Brien and Mr. Steve Rossi of ASME for coordinating various phases of this project. Established in 1880, the American Society of Mechanical Engineers (ASME) is a professional not-forprofit organization with more than 135,000 members and volunteers promoting the art, science and practice of mechanical and multidisciplinary engineering and allied sciences. ASME develops codes and standards that enhance public safety, and provides lifelong learning and technical exchange opportunities benefiting the engineering and technology community. Visit www.asme.org for more information. ASME Standards Technology, LLC (ASME ST-LLC) is a not-for-profit Limited Liability Company, with ASME as the sole member, formed in 2004 to carry out work related to new and developing technology. The ASME ST-LLC mission includes meeting the needs of industry and government by providing new standards-related products and services, which advance the application of emerging and newly commercialized science and technology, and providing the research and technology development needed to establish and maintain the technical relevance of codes and standards. Visit www.stllc.asme.org for more information.