Abstract: The depth-based evaluation criteria have not been able to meet the engineering requirement concerning
the pipeline stress concentration caused by dent， so this paper proposes strain-based evaluation procedure composed
of inline detection， noise treatment， geometric interpolation， and strain calculation. Plain dent has little influence on
pipelineresidualstrength， butitmayacceleratepipelinefracturefailurewhencombinedwithweld， crack， scratches，
and other defaults. The elastic-plastic fracture theory can be used for the strength evaluation， but when the dent is
near a weld， it must be repaired or replaced. Unconstrained dent faces the fatigue problem when internal pressure
fluctuate. The fatigue life and maintenance period are predicted based on rainflow method and fatigue damage
cumulative rule. According to the analysis and comparison of main standards and rules， this paper proposes a
completely integrity assessment system of pipeline dents.

Key words: pipeline dent, strain calculation, residual strength, fatigue life, integrity assessment