The Determination of Metal Corrosion Rates in Geothermal Condensate Using Electrochemical Techniques

Abstract

Polarization resistance measurements can provide almost instantaneous corrosion rates a s compared with coupon weight los s measurements. However, the determination of corrosion rates from the polarization resistance, requires a knowledge of the constant, B and the solution res is tance factor, in the equation: The experiments used to establish these parameters are presented and discussed. Corrosion rate measurements have been made with a Petrol i t e portable instrument in cold condensate derived from geothermal steam at Broadlands, New Zealand. The equilibrium electrochemistry of this environment is a r is ed in the form of a Pourhaix diagram on which are plotted -t h e observed corrosion potential and solution products are compared with the predictions of the diagram. Surface corrosion rate results, obtained using both commercially available and manufactured electrochemical probes are presented and compared with weight los s corrosion rate determinations.