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- Corrosion (4)
- Geothermal energy (3)
- Stainless steel (3)
- Crevice corrosion (2)
- Geothermal (2)
- Lahendong (2)
- Localized corrosion (2)
- Ni-based alloy (2)
- Sibayak (2)
- Suitability (2)
Among all of the existing electric power generation facilities, corrosion is considered to be the most severe on geothermal power plants. The focus of this research was set to evaluate the suitability of carbon steel API Q125 as a construction material on the geothermal sites Sibayak and Lahendong, Indonesia. The investigations were performed in the artificial geothermal brines under stagnant conditions by means of short-term electrochemical methods (Tafel extrapolation) and long-term exposure tests (up to 6 months). Furthermore, the influence of different parameters on the steels performance (temperature 70 °C, 100 °C and 175 °C, salinity 20 mg/L and 1,500 mg/L chlorides, pH 2 and 4) was assessed as well to ensure a “safer operating window” of a power plant.
The results showed carbon steel API Q125 could be suitable for application in stagnant geothermal brines up to temperatures of 175 °C and a chloride concentration of 1,500 mg/L. Its applicability is limited in highly acidic environments (pH 2).
In the last years, geothermal power has become a reliable and significant energy source. Because service conditions in geothermal facilities from deeply located aquifers are usually critical in terms of corrosion, materials selection is a very important issue. Preliminary evaluation of the material's suitability represents therefore a valuable strategy to ensure a secure and reliable operation of the facilities. In geothermal applications, the use of high-alloyed materials such as superaustenitic stainless steels, duplex stainless steels, and nickel-based alloys has been considered as a good alternative because of their remarkable corrosion resistance and appropriate mechanical properties. Nevertheless, the corrosion behavior of those metallic materials in geothermal fluids at service conditions has not been determined in many cases. In this work, laboratory tests including electrochemical investigations and exposure tests at 100 degrees C and 150 degrees C (1,500 kPa) showed the limits of suitability concerning localized corrosion of three different, corrosion-resistant alloys in the highly saline fluid of the North German Basin.
The corrosion behavior of different high-alloyed metals including duplex and austenitic stainless steels as well as a nickel alloy have been evaluated in artificial geothermal fluids simulating the conditions in some locations with geothermal potential in Germany as well as two sites in Indonesia.
The suitability of low alloyed steel UNS G41300, stainless steels UNS S31603 UNS S31803, UNS S32760 and super austenitic steel UNS N08031 in these geothermal fluids, investigated by electrochemical measurements and exposure tests, is limited. The nickel based alloy UNS N06059 shows excellent corrosion resistance against pitting corrosion. Excluding its high cost, it is a very good alternative to be used in the construction of geothermal facilities having highly saline brines. Stainless and duplex steels exhibit a limited corrosion resistance concerning pitting and crevice corrosion.
Beside of the higher alloyed materials, also the low-alloyed steel UNS G41300 could be employed as a constructional material for the geothermal power plant in non-saline environments, as long as the wall thickness of the material vs. corrosion rate is taken into account.
In order to provide basic information on corrosion resistance to the designers and users of geothermal plants different metallic materials including duplex and austenitic stainless steels as well as a nickel alloy have been evaluated in artificial geothermal fluids simulating the conditions in some locations with geothermal potential in Germany as well as two sites in Indonesia. By electrochemical and long-term exposure tests at 100 °C and 150 °C the suitability of low alloyed steel UNS G41300, stainless steels UNS S31603 UNS S31803, UNS S32760, super austenitic steel UNS N08031 and nickel based alloy UNS N06059 was investigated in these geothermal fluids, using critical potentials and corrosion rates. In high-saline environments the crevice corrosion turned out to be the determining mechanism. The nickel based alloy shows excellent corrosion resistance against pitting corrosion. Excluding its high cost, it is very good to be used in the construction of geothermal facilities having highly saline brines. Stainless and duplex steels exhibit a limited corrosion resistance concerning pitting and crevice corrosion. Therefore they are not suitable for highly saline brines. The super austenite UNS N08031 showed a temperature depending behavior. In non-saline environments the low-alloyed steel UNS G41300 (beside of the higher alloyed materials) could be employed as a constructional material for the geothermal power plant, as long as a sufficient wall thickness of the material is considered.
The corrosion behavior of carbon Steel and different high-alloyed metals including duplex and austenitic stainless steels as well as a nickel alloy have been evaluated in artificial geothermal fluids simulating the conditions in some locations with geothermal potential in Germany, as well as two sites in Indonesia.
The suitability of low alloyed Steel UNS G41300, stainless steels UNS S31603 UNS S31803, UNS S32760 and super austenitic Steel UNSN08031 in these geothermal waters, investigated by electrochemical measurements and exposure tests, is limited. The nickel based alloy UNS N06059 shows excellent corrosion resistance against pitting corrosion. Excluding its high cost, it is a very good alternative to be used in the construction of geothermal facilities having highly sahne brines. Stainless and duplex steels exhibit a limited corrosion resistance concerning pitting and crevice corrosion.
Besides the higher alloyed materials, also the low-alloyed Steel UNS G41300 could be employed as a constructional material for the geothermal power plant in non-saline environments with moderate pH, as long as the wall thickness of the material vs. corrosion rate is taken into account.
Geothermal sources are found to be the most aggressive natural environments for construction materials in terms of corrosion. This study was focused on investigating the suitability of stainless steel UNS S31603 in volcanic areas of geothermal sites Sibayak and Lahendong (Indonesia). Influence of different factors (temperatures up to 175 °C, chloride content up to 1500 mg/L and pH down to 2) was assessed to determine a 'safe operating window' of a power plant and assure the system integrity. Investigations were performed by means of electrochemical methods and long-term exposure tests.