Thermogalvanic corrosion and galvanic effects of copper and AISI 316L stainless steel pairs in heavy LiBr brines under hydrodynamic conditions

Thermogalvanic corrosion of the copper/copper and AISI 316L/AISI 316L stainless steel pairs was studied in heavy lithium bromide brines under hydrodynamic conditions. The galvanic coupling effect between copper and stainless steel was also analysed. The cold electrode (25 °C) was the stainless steel for the galvanic pair, whereas copper temperature varied (25, 50 and 75 °C). A hydrodynamic circuit was designed to study thermogalvanic corrosion by means of the zero resistance ammeter technique. Hot cathodes take place in stainless steel pairs while cold cathodes are present in copper/copper and stainless steel/copper pairs; this agrees with the thermal temperature coefficient of the potential sign. Thermogalvanic corrosion increases corrosion rates, especially working with copper. Weight loss measurements show that there is a combined effect due to the thermogalvanic and the galvanic effects.

► Thermogalvanic corrosion results in an increase of the current densities.
► Thermogalvanic effect increases as temperature difference between tubes is higher.
► Potentials fit linearly with increase in temperature.
► ZRA shows hot cathodes for AISI 316L while cold ones for copper and galvanic pairs.
► Weight loss tests show a combined effect between thermogalvanic and galvanic effects.