Classification and Comparison of Crack and Dent Defects in a Metal Pipe Subjected to Variable Amplitude Loading

Pipelines are commonly used to transport energy over long distances. If this structure is subjected to an internal pressure of variable amplitude loading, such as water hammer waves, the structural damage caused by the presence of a defect can be exacerbated. Previous research by the authors resulted in the development of finite element models to evaluate crack and dent defects separately. Each model was used to compare and classify defects in their respective categories based on their nocivity in a metal pipe subjected to internal pressure. The primary objective of this paper is to compare the severity of various defect categories on the same scale. A numerical damage assessment model that considers the interaction effect, as well as the loading history, is used to achieve this goal. It takes the output of the two finite element models, as well as the pressure spectrum caused by the water hammer, as inputs. This model is used to analyze the effect of key parameters that influence the severity of the defects, as well as to compare and classify the various types of dent defects with the various types of crack defects found in pipes subjected to variable amplitude loading.