Materials Performance Supplements

Corrosion Management for Pipeline Integrity 2018

Materials Performance is the world's most widely circulated magazine dedicated to corrosion prevention and control. MP provides information about the latest corrosion control technologies and practical applications for every industry and environment.

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12 JUNE 2018 W W W.MATERIALSPERFORMANCE.COM CORROSION MANAGEMENT FOR PIPELINE INTEGRIT Y SUPPLEMENT TO MP Corrosion and CP Monitoring for Buried Pipeline Integrity MetriCorr Pipeline integrity is essential to the safe and economical operation of pipeline networks. One of the largest threats to the integrity of pipelines is corrosion, a threat made more significant when the pipelines are buried or submerged. This is not only due to the obvious increased exposure to electrolyte, but also in the sense that the assets are "out of site, out of mind." Effective monitoring of the conditions experienced by buried pipelines can highlight risks associated with corrosion and provide an early warning system allowing for preemptive mitigation, while regular monitoring can ensure that preventive measures remain effective. Monitoring hardware is often only installed in applications where pipelines are protected by means of cathodic protection (CP) and is primarily used for the measurement of pipe-to-soil potential. The limits and ranges for "protection" based on these potentials are well defined. 1 However, depending on the environment and other external fac- tors, such as alternating current (AC) interference, potential (ON and OFF/IR free) alone is not necessarily a good indicator of the likeli- hood of corrosion. There are many publications highlighting the det- rimental synergism between AC and direct current (DC) densities on pipeline corrosion where high corrosion rates are experienced at DC potentials considered within the acceptable range for protection. These findings have led to industry standards and guidelines. 2 Figure 1, an extract directly from the MetriCorr WebService, shows an example of the effect of DC potential on corrosion rate, measured using a MetriCorr ICL unit and buried electrical resistance probe on a real pipeline installation. The measured actual corrosion rate is an excellent indicator of risk and implemented preventive measurement performance. It is an easy-to-understand "at-a-glance" parameter that can "overrule" current density (and potential) criteria based on acceptable corro- sion rate thresholds. Coupling measurement of corrosion rate and other electrical fingerprints (DC and AC potential, DC and AC current densities, spread resistance, and IR-free potential) yields an extremely pow- erful and versatile tool in the fight against buried pipeline corro- sion. The MetriCorr solution includes WebService presenting and storing data online for the client's exclusive use. Data can be uploaded automatically using remote monitoring devices or man- ually uploaded. Once on the WebService, data can be viewed, treated, stored, and downloaded using an intuitive, user-friendly interface allowing a pipeline operator to analyze trends and estab- lish root-cause in case of critical values. Contact MetriCorr for your corrosion and CP monitoring needs. Tørringvej 7 2610 Rødovre, Denmark Tel: +45 9244 8080 Email: info@metricorr.com Web site: www.metricorr.com References 1. NACE SP0169, "Control of External Corrosion on Underground or Sub- merged Metallic Piping Systems" (Houston TX: NACE International). 2. ISO 18086:2015, "Corrosion of metals and alloys—Determination of AC corrosion—Protection criteria" (Geneva, Switzerland: ISO, 2015). Figure 1: Selected electrical fingerprints showing the effect of DC interference on corrosion rate.

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