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Crevice corrosion of Monel 400 in sea water

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We have experienced quite severe corrosion of cast Monel 400 ball valves. The valves have been submerged in possibly polluted stagnant sea water for approx. 2 years. On testing, the balls were found not to open because of corrosion at the contact with nylon/polythene? seats.

Does anyone have info on the likelihood of crevice corrosion of cast Monel or experience of this type of problem.

All assistance gratefully accepted.

Regards

Martin Rich
Ship Repair - Plymouth, Devon, UK

July 12, 2010

All Monel is subject to crevice corrosion in stagnant seawater.

Unless cathodically protected it corrodes moderately in mud and severely under marine growth. This is accelerated by the presence of sulphides found in mud and released by bacteria in stagnant seawater (smelly!)

You will see corroboration of this on Copper Development Association website (old UK Navy work) and if you look at the datasheet at Special Metals Corporation it carries a warning to this effect.

Best wishes

- London, United Kingdom

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