Please everyone analyze the weld corrosion issue in the pipeline for oxygen and steam mixtures
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Our company has a pipeline made of 304 material, used to transport a mixture of oxygen and steam; the volume flow rate ratio of oxygen to steam is 1:1. The operating pressure of this pipeline is 3.0 MPa, and the operating temperature is 200°C. Since the pipeline was put into use, sand holes and surface cracks have occurred multiple times in the welds and within a range of 1–2 cm around them. Even after repairs or replacement of the pipeline, and after the welds were inspected successfully using X-rays, sand holes and cracks reappeared shortly thereafter. Dear sea friends, please analyze the reasons and suggest any good solutions. Thank you so much!
When changing the material, compared to oxygen pipelines, pipelines for high-temperature and high-pressure steam mixed with oxygen should use Incoloy 825, as it is resistant to oxidation as well as acid and alkali corrosion. For reference only.
There is corrosion; a corrosion-resistant coating should be applied to the inner wall of the pipeline.
It seems to be oxidation rather than corrosion. I wonder if painting the inside of the tube would work?