Abstract
Localized pitting attack remains the greatest concern on pipeline integrity in petroleum industry. Cumulative metal losses of pipelines are time-dependent, varying widely from pipeline to pipeline and region to region. The remaining wall thickness along the entire pipeline cannot be quantified simply through the general corrosion rates only. To identify the most probable locations for potential pipeline failures, the dynamic pitting concept must be implemented. Specifically, when a pitting factor was selected to characterize the metal degradation, the pitting factor must be time- and location-dependent, rather than employing a fixed value. In this paper, a theoretical derivation of dynamic pitting corrosion was firstly conducted. Following this, fundamental mechanism of pitting propagation from metastable to stable growth was elucidated. Subsequently, qualitative description of a pitting factor was introduced. Furthermore, case studies of dynamic pitting corrosion in liquid and wet-gas petroleum pipelines were analyzed. The efforts of this paper were made to generate a framework of developing dynamic pitting factors, which empowers the pipeline owners to enhance the integrity of their assets through performing a reliable assessment of cumulative wall loss for liquid and wet-gas petroleum pipelines.
