AboutAlexandre Guimarães Botelho Expertise General questions about metallurgy. Metals, fabrication processes, physical metallurgy, chemical composition and physical properties.
As my area of expertise is corrosion, fracture and extractive metallurgy, I may not respond quickly to more in-depth questions outside those fields.
Experience Up to the moment (2008) I have five years of experience in maintenance and inspection of industrial equipment, integrity assessment, reliability and failure analysis. I also have previous experience in iron mine processing unit and pelletizing process units.
Organizations PETROBRAS-Brazilian energy enterprise
Publications 9th COTEQ - Conferência sobre tecnologia de Equipamentos, 6 SIC - Simpósio Internacional de Confiabilidade, 2nd CIM - Seminário de Confiabilidade, Inspeção e Manutenção da PETROBRAS.
Education/Credentials I have technical degree in mechanics and graduation as a Metallurgical Engineer. I am also specialized in industrial equipment, maintenance and inspection, and currently specializing in Quality Engineering and Reliability Engineering.
Question I recently erected a balistrade near the sea using grade 316 stainless steel cables. Within a few weeks corrosion marks started appearing along the whole length of the cable at intervals. One two or three strands seemed to be affected. The firm that sold the cable to me suggested washing the cable down with a dish washing liquid and applying some baby oil for protection. I tried this but could not get into the grooves to clean it properly. I then tried pickling paste because that is what we use to clean and passivate welds during construction. I got it beautifully clean and I thought the problem was solved but after a few days the entire cable was red with corrosion. What is the best way to clean it so that it stays clean with the minimum of maintenance.
Answer Dear Willie,
Although SS 316 is one of the best common stailess steels for corrosion resistance, it still suffers from localized corrosion in the presence of chloride atmospheres (ie. sea water).
Also, if the cables are stretched they may corrode due to stress-corrosion under the same atmosphere.
The only way to protect it would be to passivate (create a protective homogeneous chromium oxide layer) using nitric acid immersion. Since this is a specialized procedure, it would be better if you could clean the cables again, and then, protect them by passing them through a transparent plastic tubing sealed at both ends.
