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Corrosivity of Kawerau geothermal steam

Conference ·
OSTI ID:602622
;  [1];  [2]
  1. Materials Performance Technologies, Lower Hutt (New Zealand)
  2. Faraday Technology, Inc., Clayton, OH (United States)
The Kawerau geothermal field has supplied steam to heat exchangers, turbines and other engineering plants for more than 40 years. The main construction materials are carbon and low alloy steels which show good performance for well casing and well-head equipment, pipelines and energy plant. These materials form passivating films which slow corrosion to low, acceptable levels. Thermodynamic diagrams which show domains of stability as a function of corrosion potential and solution pH, provide a basis for rationalising the corrosion product found and the corrosion rate, in comparison with observations made for other geothermal fields. The corrosivity of the steam is controlled by the hydrogen sulphide content and the balance between carbon dioxide and ammonia which determines the pH of steam condensate. The protective corrosion products formed are pyrrhotite (FeS) overlying a non-porous layer of magnetite (Fe{sub 3}O{sub 4}).
OSTI ID:
602622
Report Number(s):
CONF-971048--
Country of Publication:
United States
Language:
English

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