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Friday 22 December 2006
EXPANDING THE DURABILITY OF STAINLESS STEELS IN WATER SYSTEMS UNDER MICROBIOLOGICAL CORROSION CONDITIONS
De Cristofaro, E. Mengaroni , N. Arlt*, P. Gumpel**, D. Schiller**, Matress Serrano*** , J. Telegd****, T. Moura°, Silva° and M. Ferreira°
*KTN
**Konstanz University
***Acerinox
****CRC-HAS
°IST
Referee: V. Ferrari / F. Mancia
Final report: FRAC
The project, intends to asses the performance of typical stainless steels and newer stainless steels grades with enhanced corrosion resistance and to define tools to prevent MIC failures including recommendations and procedures for usage of stainless steels.
Targeted laboratory MIC experiments in contaminated waters were performed in order to study the MIC phenomena on the selected stainless steels. From MIC experiments, the design of accelerated MIC test methodologies, sensors and instrumentation was carried out.
The results confirmed the results obtained during the laboratory measurements: in the conditions of our experiments, the biofilm grown in the presence of SRB did not reduce the properties of the stainless steel passive films.
In the presence of manganese bacteria a potential ennoblement was observed for the examined stainless steels and the risk of getting an attack is dependent of the steel (PRE value).
MIC field experiments were carried out in the water treatment plant of C.S.M. S.p.A, Italy. The corrosion process in the water plant was the result of the synergistic action of manganese oxidising bacteria and sulphate reducing bacteria.
New countermeasures to avoid MIC failures of stainless steels in water systems were defined including environmentally-friendly inhibitors and anodic and cathodic protection.
The new natural inhibitors can be successfully applied in aqueous systems against MIC.
Cathodic and anodic systems were suitable to control MIC in the presence of manganese bacteria.
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