When processing stainless steel pipes, do not use carbon steel fixtures, otherwise the pipes will suffer from stress corrosion cracking
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A 304 stainless steel pipeline in a certain company leaked during pressure testing. Inspection revealed numerous longitudinal scratches on the surface of the stainless steel tube, with rust forming on those scratches ； Leakage starts at the rust spots. Removing the rust revealed cracks. It turns out that carbon steel fixtures were used during the processing of this stainless steel pipe, resulting in wear and scratches on its surface as well as the penetration of iron particles. In a humid atmosphere, the scratched area rusts, leading to stress corrosion cracking and resulting in cracks in the pipeline. Maintaining a uniformly clean surface on stainless steel is beneficial for improving the stability of the passivation film and preventing localized corrosion. Surface dirt, corrosion products, rust, and dust will exacerbate the corrosion conditions in local areas, thereby reducing their corrosion resistance. Using wire brushes, carbon steel fixtures, etc. to treat stainless steel causes surface contamination with iron particles, which is particularly harmful and should be avoided.
When machining 304 stainless steel pipes, the use of carbon steel fixtures caused wear and scratches on the pipe surface, as well as the embedding of iron particles. These scratches are prone to rusting in humid environments, which can lead to stress corrosion cracking and ultimately cause pipe leakage. Therefore, it is necessary to avoid using tools such as carbon steel fixtures that may cause surface contamination when handling stainless steel, in order to maintain a clean and uniform surface and thus enhance the stability and corrosion resistance of the passivation film. .