Evaluation of pipeline corrosion in sour‐gas environment

Abstract

Purpose -This paper seeks to describe the adoption and implementation of a cost-effective gas pipeline corrosion monitoring and control procedure for use in natural gas infrastructural facilities in sub-Saharan Africa. Design/methodology/approach -The incidence and severity of pipeline corrosion in a major gas production facility were monitored using a combination of instrumented field survey (potential measurements, line currents and soil resistivity measurements) and microscopic evaluation (OM and SEM) techniques. Portable field survey equipment with appropriate circuitry, contactors and sensors for potential, line current and soil resistivity measurements were used to make the field measurements. The equipment was standardized and calibrated for use in the service environment. The field survey data were superimposed on common plots in order to obtain clearer and complementary information on possible corrosion hotspots and damage locations along the submerged pipelines. Metallographic examination of the samples collected from the field was carried out to establish the type of corrosion attacks and mode of failure of the pipeline material. Findings -It was established that a combination of corrosion-related damage occurred as a result of localized attack over time. The investigation procedure was cost-effective and can be used to determine which pipeline structures are protected and to gauge with a high degree of precision the integrity of the submerged pipeline. Research limitations/implications -In the future, the procedure could be fully automated for routine on-line/on-site monitoring of gas pipelines in a sour-gas environment. Practical implications -The paper presents a useful database for the selection and/or design of corrosion-resistant materials for use in sour-gas environments and data for a comprehensive corrosion monitoring and control program in the peculiar service environment of sub-Saharan Africa, for improved performance, productivity, personnel safety and reduced operating costs. Originality/value -The information is useful to on-site engineers and operators of gas-production facilities, particularly in sub-Saharan Africa, for designing and implementing cost-effective corrosion monitoring and control programs.