Fitness for Service and Reliability of Materials for Manufacturing Components Intended for Demanding Service Conditions in the Petrochemical Industry

A methodology has been developed to quantitatively assess the suitability of use and fitness for service of candidate materials using a novel approach that includes multiple perspectives. As a case study, a carbon steel pipe has been selected for operation in the petrochemical sector. The materials studied were the following: American Petroleum Institute (API) A25, A, B, X42, X46, X52, X56, X60, X65 and X70, as well as American Society for Testing and Materials (ASTM) A-106 Gr. A, B and C. The developed model combines an analytical multiperspective approach with calculation methods based on recognized prestige standards. In the present study, the following material degradation mechanisms have been considered: generalized corrosion, fracture due to mechanical overload and high-temperature degradation. Several novel analysis elements have been incorporated into this new methodology, such as the concept of a suitability matrix and a fitness for service index. The approach allows construction of a decision diagram, and the best alternatives ordered according to the criteria and restrictions that have arisen from the analysis are obtained. Additionally, from the analysis, a series of service limitations are proposed based on the maximum hours of operation of a component. The materials ASTM A-106 Gr. A, API-A, ASTM A-106 Gr. B and API-B maintain the best balance between properties and show greater reliability versus the probability of failure due to the degradation mechanisms considered in this study. In addition, some use limitations such as critical exposure temperature have been determined for these materials (450 °C for ASTM A-106 Gr. A designation and 440 °C for API-B and ASTM A-106 Gr. B designations) to avoid the harmful effects of high-temperature operation on the material mechanical properties.