Failure analysis of float valve in transformation gas separator of coal gasification unit

Corrosion failure of a float valve in transformation gas separator unit occurred after servicing for 7 months. The failure reasons were analyzed by observation of corrosion morphology, analysis of chemical composition, examination of microstructure and analysis of corrosion products. The results show that a large amount of deformation induced martensite occurring in cold machining reduced the corrosion resistance of the float valve greatly. The joint action of activation corrosion caused by H₂S and pitting caused by Br^- made the float valve fail seriously.