A SIMPLE METHOD TO ESTIMATE CORROSION RATES AND CP PENETRATION IN COATING-DISBONDED REGIONS ON BURIED PIPELINES

摘要

This work reports two easily implementable, four-step procedures respectively to estimate corrosion potentials and rates in coating-disbonded regions based on measurable soil chemistry, lab-measured pipe steel open circuit potential (OCP) and corrosion rates in deaerated soil ground water and the CP potential near a holiday. This avoids the need for excavation, except as a confirmatory measure, while allows for the corrosion condition in a disbondment to be evaluated. This method can be used to estimate conservative but more realistic corrosion rates in the disbonded region. The corrosion rates thus obtained can be used to prioritize susceptible corrosion locations for excavation and determine more confidently reassessment interval. These simple procedures are not applicable for use to estimating growth rates of pits or cracks if they are present in the disbonded region.