2015 by John Wiley & Sons, Inc. All rights reserved. Current technologies for detecting and monitoring the state of external corrosion of oil and gas pipelines consider the system as electrochemical or electrical in nature. This chapter summarizes the description, quantification, and influence of critical factors for external corrosion of buried pipelines. The classification of the factors is based on the multiscale approach for onshore pipelines, considering the soil/pipeline system as an electrochemical cell. Pipelines are exposed to and interacting with various environmental elements causing integrity damage. Historically, resistivity has often been used as a broad indicator of soil corrosivity. The chlorides and sulfates present in the soil can also influence the corrosivity of the soil and damage evolution of the pipeline/soil system. Ideally, any highly corrosive environments along a proposed pipeline route would be identified before pipeline installation. The main methods for corrosion mitigation on underground pipelines are coatings and cathodic protection (CP).
