Section of a steel pipe

Section of a steel pipe

Source: BAM

Geothermal energy is an interesting alternative to polluting fossil energy sources. Therefore, in Belgium, two wells have been drilled for a deep geothermal power plant. However, the environment to which the installations are exposed is challenging.

In this region the brine contains 165 g/L totally dissolved salt components (of which 90 % are sodium and chloride). The production temperature is expected to be up to 130 °C. In order to assure a sufficient service life, the suitability of desired construction materials was determined by investigating the corrosivity of the artificial brine to low-alloyed carbon steel (S235JR), austenitic stainless steel (UNS S31603) and duplex stainless steel (UNS S31803). This was investigated by exposure and electrochemical tests.

For carbon steel, uniform corrosion was found with quite acceptable corrosion rates. So, it could be considered as constructional material, if a sufficient wall thickness is chosen. Both higher alloyed steels demonstrate very low uniform corrosion rates. However, they showed pitting and crevice corrosion susceptibility.

Corrosion behaviour of different steel types in artificial geothermal fluids
Willem Faes, Steven Lecompte, Johan Van Bael, Robbe Salenbien, Ralph Bäßler, Inge Bellemans, Pieter Cools, Nathalie De Geyter, Rino Morent, Kim Verbeken, Michel De Paepe
published in Geothermics 2019, Volume 82, Pages 182-189
BAM, Division Corrosion and Corrosion Protection