Abstract: After the reformer for hydrogen production in certain refining enterprise was upgraded and revamped in 2010, five cracks have occurred in the reinforced joints of different furnace tubes and in the weld junction of the upper tail pipe, resulting in unplanned shutdown of the hydrogen production plant. Through in-depth analysis of the operating environment, high-temperature hydrogen corrosion, thermal expansion stress, structural stress, dissimilar steel welding, spring support hangers, etc., it was found that the leakage was mainly due to the stress relaxation cracking in the local high-stress area of the weld connecting the reinforced joints and the upper tail pipe, and meanwhile, the process parameters were not strictly controlled, which increased the cracking speed. In 2021, through the implementation of furnace tube material upgrading, stabilization of process operating environment, strict control of construction quality and other measures, there has been no more cracking; the safety hazards during the operation of the furnace tube have been completely eliminated; and the intrinsic safety of the equipment and the long-cycle operation of the device have been guaranteed.

Key words: furnace tubes, dissimilar steel welding, structural stress, joint cracking, material upgrade