Life Management Assessment of Service-Exposed HP-Modified Reformer Tubes and Influence of Material Variability

Steam methane reforming (SMR) is widely used as the primary method of production for bulk hydrogen worldwide. The reforming process is endothermic so components, such as centrifugally cast reformer tubes, require the use of heat resistant materials to withstand continuous operation at temperatures exceeding 815°C (1,500°F). Life management of these components is challenging because of the potential for furnace temperature imbalances, variability in tube processing parameters and compositional requirements due to the lack of standardized specifications, and limited long-term creep data available for HP-modified and HP-microalloyed grades. This study aims to evaluate the influence of material composition and microstructural evolution (induced by service aging) on high temperature creep performance using a full tube set (four distinct tube sections) of ex-service HP40-modified reformer tubes and a restricted chemistry HP-modified variant in the new condition. Traditional round bar creep specimens were evaluated using the Omega method and results are discussed. Creep damage and microstructural evolution were characterized using a variety of advanced microscopy techniques. Results indicate that long-term exposure to high temperatures and concomitant microstructural evolution reduce overall component life; however, other factors such as material composition and macrostructure influence creep performance and damage manifestation. Specific impacts linked to location in the furnace, variability in macro and microstructure, and material composition are addressed.