Review of Material Selection for Corrosion-Resistant Alloy Pipelines
Abstract
The selection of materials for subsea pipelines is critical due to the highly corrosive nature of the environments, in which these pipelines operate. Traditionally, carbon steel has been used for non-corrosive applications or when an active corrosion management strategy is employed. However, the use of carbon steel is limited in situations where corrosive fluids, such as those containing chlorides, hydrogen sulfide (H₂S), and other aggressive substances, are present. In such cases, corrosion-resistant alloys (CRAs) offer a more effective alternative. This paper provides a comprehensive review of the material selection process for CRA pipelines, specifically focusing on corrosion mechanisms such as general corrosion, pitting, crevice corrosion, chloride stress corrosion cracking (CSCC), and hydrogen-induced stress cracking (HISC). The paper examines commonly used CRA materials, including duplex stainless steels, super duplex stainless steels, Alloy 825, and Alloy 625, comparing their performance under different subsea conditions. Resistance of each material to various forms of corrosion is discussed, along with considerations for operational and economic viability. The review highlights that while CRA pipelines typically have higher initial costs than carbon steel pipelines, they offer significant long-term savings by reducing corrosion maintenance, inspection, and repair costs. The review findings also emphasize the importance of proper CRA material selection, particularly in the presence of complex environmental factors such as high temperatures, high pressures, and the presence of chlorides and H₂S. The paper concludes that the appropriate use of CRA materials can significantly enhance pipeline integrity, extend operational lifespans, and prevent costly failures, making them a critical choice in the design and construction of subsea pipelines.