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The following are typical sulfide stress corrosion cracking cases related to the absorption and analysis tower of the catalytic cracking unit.: 1. A case of wet H₂S corrosion and stratification in the middle section cooler of the absorption tower. The reflux cooler in the middle section of the absorption tower of a catalytic cracking unit of a refining and chemical company has a shell material of 16MnR. The shell side medium is mid-section oil containing a large amount of H₂S, NH₃ and a small amount of CN⁻, forming an H₂S-HCN-H₂O wet hydrogen sulfide corrosion environment. During the corrosion process, hydrogen atoms generated by the reaction between H₂S and iron penetrate into the steel and are enriched to form hydrogen molecules at defects such as inclusions in the steel plate. Local high pressure triggers hydrogen-induced cracking. Finally, large-area delamination defects appear in the shell, with the largest defect area reaching 56 cm², and the wall thickness in some areas is severely thinned. 2. A case of stress corrosion cracking of the desorption tower bottom reboiler in a refinery. The shell material of the desorption tower bottom reboiler is A3R, and the shell side medium is deethanized gasoline. The water accumulated at the bottom concentrates the sulfide, forming a wet hydrogen sulfide corrosion environment. The hydrogen atoms precipitated by the corrosion reaction are difficult to combine into hydrogen molecules under the action of sulfide, and penetrate into the interior of the steel in large quantities to increase the brittleness of the material. Under the combined action of welding residual stress and working tensile stress, local perforation and cracking eventually occur, which is a typical wet hydrogen sulfide stress corrosion failure. 3. A case of sulfide corrosion and fracture of the absorption tower cooler bolts and tube bundles. In the middle section of the absorption tower of the catalytic cracking unit of a petrochemical company, the total sulfur mass fraction of the oil in the middle section of the shell side reached 125 μg/g. The material of the internal floating head bolts was 35CrMoA. Under the coupling effect of the high sulfur medium and the low-speed flow of circulating water, sulfide stress corrosion occurred. Six bolts broke directly, and the tube bundle port appeared at a depth of 0.2~0.3 mm pit corrosion, the depth of corrosion pit on the pipe box partition is up to 2.0 mm.