ZHANG Peng, FU Yichuan, ZHAO Zhenxu, et al.Analysis and Repair of Cracks in the Cracking Furnace of Ammonia Decomposition Unit[J].Electric Welding Machine, 2023, 53(10): 78-83. DOI： 10.7512/j.issn.1001-2303.2023.10.12.
Analysis and Repair of Cracks in the Cracking Furnace of Ammonia Decomposition Unit
A furnace of cracking furnace of ammonia decomposition unit is made of heat-resistant stainless steel-welded, and the partial welded joint cracks in the process of long-term high-temperature operation. In order to ensure the safe production of heat-resistant stainless steel furnace liner, the reason for the occurrence of furnace liner cracks is that S31008 austenitic stainless steel continuously precipitates a network of brittle Cr,23,C,6, carbides along the grain boundary during long-term high-temperature operation. Under the action of working stress, the cracks propagate along the grain boundary, causing fracture along the grain boundary. In addition, the operating temperature of the cracking furnace and the inconsistency in the dimensions of the elliptical head and intermediate nozzle, as well as the intermediate nozzle and tube bundle, cause stress concentration and prevent synchronous shrinkage, resulting in residual tensile stress. Using ER310 welding wire and tungsten argon arc welding for welding repair. After the non-destructive testing of the weld, it was found that the fusion line between the weld and the base metal was clear and regular, the fusion was good, and the furnace liner after welding repair could meet the requirements of normal use.
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