Abstract
In order to maintain profitable margins in the refining industry, hydroprocessing reactors occasionally require new internal support rings or gussets to accommodate revised catalyst bed heights or quantities. Historically, this has been solved by adding an internal skirt to raise or lower the effective distribution height, but this can create distribution issues and increases the complexity of the internals. An alternative approach is to weld new support rings or gussets onto the weld overlay or cladding of existing reactors. However, this approach is not commonly accepted, and many owners shy away from it to avoid the potential repercussions of performing the weld incorrectly. To address these concerns, this paper discussed the key considerations of this process associated with the degradation mechanisms, and provided guidelines on startup and shutdown, inspection, stress requirements and welding procedures in order to perform this process safely. Several case histories were presented for adding light load bearing attachments to the overlay or cladding of the hydroprocessing reactors. It has been demonstrated that welding new supports to the overlay or cladding of the hydroprocessing reactors can be managed safely and in a cost-effective manner when the proper design, shut down/startup procedures, inspection techniques, welding procedures and production controls are utilized.
