X80管道凹陷结构失效与极限凹陷深度研究

Study on Structural Failure and Critical Dent Depth in X80 Pipelines

摘要: 为精确评估X80输气管道凹陷缺陷的安全状态，克服传统经验判据(H/D)的局限性，本文建立了凹陷管道形成与在内压作用下恢复的全过程有限元模型。采用Ramberg-Osgood非线性本构模型描述X80钢的弹塑性行为，并以10%等效塑性应变为失效准则，对某Φ1422 × 32.1 mm管道进行了安全校核。结果表明：当凹陷深度达15% D时，最大塑性应变高达52.76%，远超限值；在高压、大口径X80管道工况下，其极限凹陷深度仅为管径的1.7%，远低于常用经验值。本研究为在役高强度钢管道的完整性管理提供了科学、可靠的数值评估范式，并对管道检测、维修与决策提供了重要的量化依据。

Abstract: To accurately assess the safety of dent defects in X80 natural gas pipelines and overcome the limitations of traditional empirical criteria (H/D), this paper establishes a full-process finite element model that simulates the formation of a dented pipe and its subsequent recovery under internal pressure. The nonlinear Ramberg-Osgood constitutive model was adopted to describe the elasto-plastic behavior of X80 steel, and a failure criterion of 10% equivalent plastic strain (PEEQ) was applied to conduct a safety evaluation on a Φ1422 × 32.1 mm pipeline. The results show that when the dent depth reaches 15% D, the maximum plastic strain is as high as 52.76%, far exceeding the allowable limit. The study further demonstrates that, under high-pressure, large-diameter X80 pipeline conditions, the critical dent depth is only 1.7% D, which is significantly lower than commonly used empirical values. This research provides a scientific and reliable numerical evaluation paradigm for the integrity management of in-service high-strength steel pipelines and offers a crucial quantitative basis for pipeline inspection, maintenance, and decision-making.