Pressure machine inlet filter short piping could produce cracks in a short time. Crack parts of the macroscopic examination, chemical composition analysis, tissue imaging, scanning electron microscopy analysis, and mechanical analysis were studied. The results showed that in the corrosive medium containing H ₂S, the flange and the nozzle were subjected to welding residual stress during the manufacturing process, and the welding residual stress caused stress corrosion, resulting in cracking along the embrittlement.