The Role of Specifications, Quality Assurance, and Inspection in the Successful Use of Corrosion-Resistant Alloys in Geothermal Applications

Abstract

In many geothermal fields, the characteristics of produced fluids result in unacceptable degradation rates of mild steel. Corrosion-resistant alloys (CRAs) can significantly reduce or virtually eliminate in-service degradation. However, initial material cost and related fabrication cost can be several times the cost of comparable mild steel components and assemblies. Errors in material processing or fabrication can result in dramatic increases in susceptibility of alloys to corrosion and cracking. Therefore, it is important for operators to recognize and address the potential for avoidable loss of alloy performance resulting from improper manufacturing and fabrication practices. This paper explains the various means by which corrosion resistance can be degraded during manufacturing and fabrication. It also includes descriptions of how carefully developed and implemented specifications, quality assurance, and inspection practices can be used to target the potential sources of property degradation. Finally, case histories are used to illustrate how failure to specify the appropriate material requirements and/or failure to qualify and monitor manufacturers and fabricators can result in avoidable degradation of material performance.