This WRC Bulletin entitled “Evaluation of Material Strength Data for Use with API Std 530” is one of a series of Welding Research Council, Inc. (WRC) Bulletins intended to capture in detail the technical information that supports important and widely used international codes and standards such as those of ASME and API. The results of programs WRC and its Materials Properties Council (MPC) and Pressure Vessel Research Council (PVRC) have for over 50 years played instrumental roles in advancing the technology needed to assure reliability and safety of pressure vessels and structures designed and fabricated to ASME, API and other internationally recognized standards.The data for the project resulting in this publication were gathered and analyzed by MPC under an API contract. It was logical that MPC was selected for this study of properties applicable to high-temperature tubular materials produced by modern steel making practices for petroleum refinery heaters designed to API Std 530. More than 50 years ago Dr. George V. Smith acting under the auspices of MPC and its forerunner, the ASTM-ASME Joint Committee on the Effects of Temperature on the Properties of Materials, collected and evaluated much of the data that was used by API to support the design curves that would appear in API Std 530. The Joint Committee and MPC later pioneered in development of statistically rigorous computerized techniques for analyzing and extrapolating elevated time-dependent mechanical property data. The methods developed were applied to optimize Larson-Miller Parameter (LMP) stressrupture constants for each material as desired by API for use in the latest API Std 530. Optimization of LMP constants enhances the accuracy of property extrapolation for the purpose of remaining life assessment and creep damage as well as design.The polynomial expressions provided for the LMP parameters and all other mechanical properties in this WRC Bulletin are intended to support computerized design and life assessment activities. For further details about tools for life assessment the reader is referred to API/ASME FFS-1 on Fitness-For-Service. Detailed presentations of solutions to the example problems in this Bulletin demonstrate implementation of the methods recommended.