Dear David, First of all it is not a very prudent idea of hydrotesing the tank with the sea water. The next desastrous thing which you have mentioned is leaving the sea water in the tank for more than one month. Another bad aspect is that tank is not coated. Under the following situations the Tank would be subjected to very degree of risk by the pitting type corrosion because of following reasons. 1. High Chloride content in sea water 2. stagnancy 3. Presence of Oxygen ( as the Tank will be open to atmospheric conditions) As a remedial measure please drain out the sea water and check for the pitting type corrosion. Let us have your feed back on your observations. Regards, Shabbar Hussain Refinery Corroson Engineer

Actually we found no affect I don’t know must there is a corrosion at shell but, it seem to me it is old practice and accepted