oa Test Sample Development And Test Procedures For Establishing A Chloride Stress Corrosion Cracking Corrosion Atlas For Qatar

Test Sample Development and Test Procedures for Establishing a Chloride Stress Corrosion Cracking Corrosion Atlas for Qatar H. Farhat*, R. Johnsen** & D. Roulston** Abstract Oil and gas production, and petrochemical plants in offshore and onshore locations in Qatar are exposed to severe environmental conditions. The combination of high humidity, high concentration of chloride ions, high temperature and the presence of residual tensile stresses due to welding or other forming process make these facilities susceptible to chloride-induced stress corrosion cracking (CSCC). High temperature causes seawater to evaporate, condensate, and dry on metal surfaces, thereby enhancing local build-up of aggressive species, such as chloride on the metals' surfaces. If the surface of the metal is insulated, the condensate may be trapped under the insulation leading to high localized corrosion damage. This is complicated by sand storms which leave sand particles with aggressive species such as chloride and sulfide on the surfaces exposed to this environment. A corrosion atlas for chloride stress corrosion cracking was developed in Qatar. Seven different stainless, duplex and high nickel alloy steels were investigated. One hundred samples of each material were exposed to a stress equivalent to 80% and 100% of their yield strength. They were then, distributed in different onshore and offshore sites for Qatar Petroleum, and were inspected periodically for CSCC. The temperature, humidity and time to failure were recorded. This paper describes the samples, and sample rack design, testing procedure, as well as the stress application method applied to the samples. *College of the North Atlantic-Qatar ** Qatar Petroleum Research and Technology Department