Session: CS-13-01: High Temperature Codes and Standards

Paper Number: 84248

84248 - Demystifying the 1.1 Factor for Tensile Strength Above Room Temperature in Development of the Boiler Code Stress Tables the 1.1 Factor for Bpvc Ultimate Tensile Strength Values Above the Room Temperature 

As the Boiler and Pressure Vessel Code (BPVC) increasingly gains popularity worldwide for engineering design and construction, it is not uncommon that many users are mystified by the 1.1 factor required for ultimate tensile strength values above the room temperature in Section II Part D stress tables.  Questions often arise about the origin and purpose of the factor, its due considerations when evaluating an alloy for acceptance to design and construction use from the perspective of the alloy’s tested tensile strength value, and the reason why the factor is not applied to the yield strength values.  Without sources for reliable and explicit explanations, users tend to misinterpret the factor and its requirement, incorrectly change their alloy acceptance standard, and risk or over strengthen the safety margin in their structural design.

To help the users with these frequently asked questions, particularly users in nuclear industry where rigorous criteria are required for alloy acceptance, this paper is intended to demystify the 1.1 factor and facilitate confident and knowledgeable use of the BPVC Section II Part D stress tables in component design and alloy selection.  The process for developing the yield and tensile strength values for the BPVC stress tables is first reviewed.  The provenance and purpose of the 1.1 factor are then discussed.  Effect of the factor on alloy tensile strength in component design applications is evaluated with examples.

Presenting Author: Weiju Ren Oak Ridge National Laboratory

Presenting Author Biography: Dr. Weiju Ren is a senior scientist at the Oak Ridge National Laboratory and an ASME Fellow. His R&D interests cover high temperature materials, mechanical behavior and analysis, materials informatics, verification and validation of advanced modeling and simulation, and integrated computational materials engineering. Since 2005 he has been serving as Manager of Operations for DOE’s Gen IV Materials Handbook Project to coordinate the international collaboration of Australia, Canada, China, European Union, France, Japan, South Korea, South Africa, Switzerland, United Kingdom, and United States for development of advanced nuclear energy systems, and currently leads the technical development of ASME Materials Properties Database that supports the ASME Codes and Standards particularly the Boiler and Pressure Vessel Code.

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