Materials selection for dew-point corrosion in geothermal fluids containing acid chloride

The paper is aimed to the evaluation of the corrosion behavior of corrosion resisting alloys (CRAs) in geothermal fluids operating at the dew point. Several test series were carried out in geothermal production sites of Tuscany (Italy) under continuous flow. The vapor was extracted directly from the main flow and it was conveyed in an experimental device designed to simulate dew point conditions. Nine martensitic stainless steel, one precipitation hardening stainless steel with martensitic structure, two ferritic extra low interstitial (ELI) stainless steels, four duplex (austenitic-ferritic) stainless steel, five austenitic stainless steels, six nickel alloys/super austenitic stainless steels, four titanium alloys were tested. The main forms of corrosion were general corrosion, localized corrosion (pitting and crevice) and stress corrosion cracking. Corrosion maps are presented as a function of PREN index, chromium, molybdenum and nickel content.