Oxygen pipeline corrosion
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Recently, we have been experiencing continuous corrosion and leaks in our oxygen pipelines; each time a pipeline is replaced, it starts leaking again after no more than a month. The pipes we use are made of 304 material, with steam added to the oxygen, and the steam temperature is 300°C. The pipeline pressure is 2.4 MPa, and chlorine ions have now been detected in the steam. Yellowish substances are always found whenever the pipeline leaks. I would like to ask everyone: under such conditions, what should be the maximum allowable level of chloride ions in the medium?
Water vapor plus chloride ions – still stainless steel 304! It would be strange if it didn’t corrode! Change the material!
The presence of a significant amount of oxygen in the steam exacerbates pipeline corrosion; this is why dissolved oxygen in boiler feed water must be strictly controlled. Chloride ions are a factor that causes corrosion in stainless steel; to address this issue, it is necessary to determine the concentration of chloride ions and their specific source. Metal corrosion is actually a process of oxidation, and the presence of chloride ions accelerates this oxidation process, as chloride ions can quickly carry away the corrosion products, leading to new areas of corrosion forming more rapidly.
For pipes made of austenitic stainless steel (304 belongs to austenitic stainless steel), the chloride ion content in the fluid medium should not exceed 25 mg/l (25 ppm). The boiler water used to generate steam is soft water (which only has calcium, magnesium and other cations removed, while anions such as chlorine and sulfate remain). To improve this situation, it is recommended to replace soft water with deionized water (water from which both cations and anions have been removed). For your reference
Where can I find the standards? I need more professional information; could you help me out?