MICROBIOLOGYCALLY INFLUENCED CORROSION OF SHEET STEEL PILING IN THE PERSIAN GULF

As part of a general condition survey in connection with remedial works to a in the Persian Gulf, approximately 900 liner meters of steel sheet piling was checked for corrosion and loss of section. The typical corrosion pattern showed a moderate loss of section in the splash zone and a greater loss at the low water zone. However, at one particular location in the coaster severe corrosion of the sheet steel piling had led to perforation of the front out pan piles at the low water zone. Marine fouling was removed from a corroded area in the low water zone and the corrosion product were examined. Chemical analysis showed iron sulphide to be a prime constituent of the corrosion product and microbiological analysis evealed high number of sulphate – Reducing Bacteria (SRB) in the vicinity of the corrosion . these finding , together with some of the site observation, have led the authors to conclude that the corrosion of the piles at the tidal zone was heavilt influences by the activity of SRB. Details of the relevant evidence, together with recommended methods of preventing further corrosion, are provided.