In high temperature applications, dissimilar welds made with nickel-base alloy filler metals provide extended service lives as compared to similar welds made with stainless steel filler metals. Although considerable refinery experience exists, it is difficult to find published information for pressure boundary welds made with nickel-base filler metal in hot hydrogen and/or H2S services. The Amuay Refinery has used nickel base alloy filler metals to join clad piping components in a number of piping applications. This paper details the results of an analysis of clad 1 1/4 Cr- 1/2 Mo steel hydroprocessing reactor effluent piping samples removed from service to assess the long term effects of hydrogen and H2S on the dissimilar weld.
Results of mechanical testing and metallurgical analysis reveal that no significant loss in properties occurred. Details of the weld procedures and weld joint design are provided.
Keywords: Dissimilar Metal Welds (DMW), sulfidation, hydrogen, H2/H2S, hydroprocessing, hydrotreating, hydrodesulfurizer (HDS), nickel, stainless steel, reactor, effluent, clad pipe, cladding, sensitization, stress corrosion cracking (SCC), polythionic acid SCC (PSCC), intergranular corrosion.