Influence of design and initial surface preparation of the samples on SSC-A test result

摘要

The metallic materials used in oil & gas fields are subjected to aggressive and corrosive environments. The combined presence of H_2S gaz in a saline sour environment can lead to the failure of the material. Therefore, materials are qualified priory to be in service. One of the international standards is the NACE TM0177-2005 which describes several methods to qualify metallic material, as SSC-A test. SSC-A test is a uniaxial tensile test in a corrosive environment. The surface preparation for the sample is detailed by machining & polishing. The influence of several surface preparations on SSC-A test results was analysed in this study. The effect of machining & polishing on corrosion and cracking susceptibility has been experimented. These experiments were performed on steel samples used in oil industry. The aim was to describe the corrosion phenomena vs surface preparation and to compare with a sample as-received, then representative of service conditions. The test results are very different, ranging from severe corrosion and break or crack observed to a slightly corrosion without crack initiation. Ultra-sonic controls were performed to associate these results with the presence of dissolved hydrogen as Hydrogen Induced Cracking HIC.