Pipeline transportation is the core lifeline of the global energy supply system

but dent defects caused by third-party damage

construction errors

and other factors seriously threaten the safe operation of pipelines. As one of the most common defects in pipelines

dents will lead to local stress concentration and residual stress

accelerate fatigue crack initiation and propagation under cyclic service loads

and significantly shorten the pipeline fatigue life

even inducing leakage and explosion accidents. To accurately grasp the key factors affecting the fatigue life of dented pipelines and provide theoretical and engineering support for pipeline integrity management

this study systematically investigates the influencing factors of the fatigue life of dented pipelines through the combination of theoretical analysis

experimental testing

and numerical simulation. The research focuses on three categories of key factors: dent's own parameters (depth

length

width

shape

composite defects)

pipeline's own parameters (material

diameter

wall thickness

location)

and external related factors (internal pressure fluctuation

temperature change

corrosive environment

third-party loads). The results show that dent depth is the most critical influencing factor

and the fatigue life decreases exponentially with the increase of depth; composite defects (dent + crack

dent + corrosion pit) have a significant synergistic damage effect; high-grade steel materials

larger pipe diameter and wall thickness can effectively improve fatigue resistance; internal pressure fluctuation

high/low temperature

and corrosive environment will accelerate fatigue damage. Based on the research results

quantitative models of fatigue life related to key influencing factors are established

and corresponding engineering suggestions for inspection

maintenance

design

and construction are put forward. This study clarifies the intrinsic mechanism of fatigue failure of dented pipelines

improves the theoretical system of pipeline fatigue evaluation

and provides a reliable technical tool for the safe operation and integrity management of dented pipelines.