A new « Case Studies in Engineering Failure Analysis » online 17 June 2014, about the cracking leakage accident of deaerator/sourgas stripper cylinder in a chemical fertilizer plant. The analysis results indicated that improper welding was the main reason for the cylinder cracking failure. Chromic carbide (Cr23C6) was precipitated at partial grain boundaries of the transition region between base metal and weld seam and induced the depletion of Cr element at the grain boundary and in the vicinity of grain boundary. Cl− in the media was enriched at the grain boundary of chromium depletion region and formed pitting corrosion, which could lead to stress-corrosion cracking of cylinder under tensile stress.