Corrosion resistance of different steel grades in the geothermal fluid of Molasse Basin

Abstract

Long‐term corrosion resistance of carbon steels grade API L80 and API Q125 has been evaluated by means of electrochemical measurements and exposure tests in the Molasse Basin, one of the most important geothermal fluids in Europe. In addition, the localized corrosion resistance of the duplex stainless steel alloy 2205 and the austenitic stainless steel grade 316L was determined at 100 and 150 °C. In general, investigated materials showed a remarkable resistance to uniform and localized corrosion. Their corrosion behaviour at service conditions is discussed in this paper.

Corrosion Behaviour of L80 Steel Grade in Geothermal Power Plants in Switzerland

“…The most common types of corrosion are uniform, pitting, and crevice corrosion [41]. In bicarbonate environments with very low chloride concentrations, low-alloyed carbon steels show noticeable resistance to uniform corrosion [32]. However, environments with high chloride concentrations and low pH (around 6) might lead to uniform attack and to the formation of pits on the steel surface [28][29][30].…”

“…This results in a limited knowledge about properties of deep geothermal fluids (at depths of 4-5 km) [10] and, thus, a lack of expertise in corrosion issues of geothermal installations. Furthermore, literature on corrosion shows that most of the experimental studies are restricted to specific geothermal fields [23,[28][29][30][31][32]. Considering that the fluid chemistry might significantly vary not only between physically separated fields but also between nearby boreholes [33,34], the transfer of technical know-how of existing geothermal power plants abroad to design durable, maintenance-free facilities in Switzerland constitutes a research challenge.…”

Suitability of UNS S31603 steel for geothermal brines in volcanic areas – Influence of different physicochemical conditions on its corrosion behavior

“…Its vulnerability is observed with an increase in temperature and concentration of halide ions that initiate localized corrosion (PREN = 23.1-28.5) (Goldberg, 1976). Several authors investigated already the corrosion behavior of alloy UNS S31603 for geothermal industry (Mundhenk et al, 2013;Klapper et al, 2013). They confirmed its excellent resistance to uniform corrosion and susceptibility to localized attack at increased temperatures and chlorides concentrations.…”

A comprehensive approach based on SVM to model pitting corrosion behaviour of EN 1.4404 stainless steel

“…This solution will provide the best generalisation performance. For the case of not linearly separable data, there is any hyperplane for which all points in training set satisfy Equation (8). To deal with this problem two parameters are included in the optimisation problem given by the following equation:…”

“…Pitting corrosion has been considered one of the most critical types of localised corrosion that can lead to failure of structural components affecting their service life [5]. Many authors have developed studies about this phenomenon [6][7][8]. Some of them have been focused on analysing the influence of environmental factors on corrosion behaviour, concluding that principal environmental variables affecting corrosion behaviour are chloride ion concentration, pH and temperature [9][10][11].…”