Abstract: The mechanisms by which interactions between corrosion defects at different relative positions affect pipeline failure pressure are unclear. Therefore, a three-dimensional finite element model was constructed to simulate pipeline failure pressure under different corrosion-defect conditions and to determine the effects of parameters such as the relative position, length, and depth of the defects. The results show that as the interaction between defects intensifies, the failure pressure decreases significantly, with relative position, geometry, and spacing identified as the main controlling factors. The strongest interaction between defects occurs when their relative positions are tangential. As the defects overlap or the spacing increases, the interaction effect gradually weakens. When the circumferential spacing is ≥ 0.6, and the axial spacing is ≥ 0.8, the defect interaction can be ignored, and the defects can be evaluated independently. The axial spacing has a greater impact on failure pressure than the circumferential spacing. Furthermore, increasing the defect length reduces the failure pressure, while increasing the defect depth strengthens the interaction and further compromises pipeline integrity. To describe these effects, a new formula is proposed that explicitly integrates defect geometry, spacing, and material strength to define the critical spacing and failure pressure under interaction conditions. These findings can serve as a reference for assessing corroded pipelines and guiding the development of maintenance strategies.