Material selection of titanium alloy pipelines considering multi-criteria in an acidic environment based on analytic hierarchy process

In the construction of offshore oil and gas projects, the selection of pipeline materials is significant and challenging. In the complex marine environment, it is difficult to ensure the safe service life of oil and gas pipelines selected only based on the consideration of the corrosion resistance of materials. Therefore, multiple performance indicators should be comprehensively considered in the material selection. The partial pressure of H₂S and CO₂ in the oil and gas of an offshore block was as high as 2 MPa and the temperature of the transported fluid was up to 70 °C. Rock particles were carried in the fluid. In this study, TA3, TA10, and TA36 titanium alloy materials to be used in this block were evaluated through various tests, including physical and chemical tests (tensile test, impact test, bending test, and hardness test), friction wear test, gas-solid erosion test, corrosion test, and corrosion wear test. In this paper, based on the consideration of the performance indicators and expert knowledge corresponding to the above tests, a material selection method based on analytic hierarchy process was proposed and the priority in the material selection of marine pipelines was studied. In addition, the microstructures and element distributions of the tensile and impact fractures, erosion pits, and friction traces of the materials were studied by a scanning electron microscope, an energy dispersive spectroscope, and a laser confocal microscope. The results of hierarchical analysis showed that the selection priority of TA3, TA10, and TA36 titanium alloys was TA10 < TA3 < TA36. TA36 titanium alloy was the best material choice for the submarine pipeline system in the target area and the corresponding weight was 0.60121. The results provided the basis for the selection of the best material alternative for the construction of submarine pipelines in this block.