Fatigue life assessment of damaged pipelines under cyclic internal pressure: Pipelines with longitudinal and transverse plain dents

• A methodology for fatigue life assessment of dented steel pipes is refined.
• The methodology concerns high cycle fatigue and uses stress concentration factors.
• Stress concentration factors of longitudinal and transverse dents are evaluated.
• Expressions for stress concentration factors due to these dent shapes are obtained.
• The methodology can deal with spherical, longitudinal and transverse dent shapes.

This ongoing work aims to refine a methodology for fatigue life assessment of dented steel pipelines under cyclic internal pressure. A numerical model is developed to obtain stress concentration factors on dented pipes under internal pressure. A comprehensive parametric study is accomplished and analytical expressions to estimate stress concentration factors for spherical, longitudinal and transverse plain dents as a function of selected geometric parameters are developed. The proposed fatigue assessment methodology is validated from fatigue test results. Here, the analytical expressions are refined to include a more complete dent geometry definition for transverse, longitudinal and short longitudinal dents.