Reformer tubes: Not a commodity

Abstract At the heart of the primary reformer are centrifugally cast alloy steel tubes. These tubes experience the extreme conditions required for steam methane reforming and thus require high quality to achieve their expected design life. The tube designs need to balance heat transfer rates, optimize catalyst volumes and minimize thermal stresses, while not compromising the tube life expectancy. Centrifugally cast heat resistant alloys have proven themselves as the ideal material for this service. Individual cast tubes are custom made so it is important that the buyer be aware of the manufacturing methods of these products: to be aware of potential pitfalls and to appropriately specify the inspection and quality assurance requirements. Each tube segment is cast individually from a small heat, resulting in a unique chemical composition. Subsequent boring, machining, welding, and inspection operations are important to ensure the quality of the tube segments and the final reformer tube assembly. The reformer tube manufacturing process, including casting, machining and fabrication, is presented with the typical inspection operation. Some defects in the design and fabrication are described. These defects have caused ammonia and syngas plant shutdowns at a great expense to operating companies. Such defects can be avoided at the design or specification stage or during quality control tests. This paper describes how to avoid such defects. © 2007 American Institute of Chemical Engineers Process Saf Prog, 2007.