Corrosion processes and control in recirculating cooling water systems in refinery and petrochemical industry

The corrosion activity of tree RCWS in Bulgaria were investigated. The high est corrosion rate was observed in RCWS-1, a system typically contaminated by oil products. In this specific case the metal coupons were covered by a uniform and dense bio-corrosion fouling. The maximum corrosion rate registr ed during the first 200 h of testing was 0.5 mm/y. These results were confi rmed by electrochemical potential measurements and monitoring. The Moessbauer spectra and thermomagnetic analysis of deposits from surface s of real heat exchangers were obtained. There is an indication of FeS2 (py rite) and Fe7S8 (pyrolite) as corrosion products in the samples studied, wh ich can be attributed to a SRB activity in the cooling water.