Comparison of Techniques for Monitoring Corrosion Inhibitors in Oil and Gas Pipelines

• Published in: Corrosion (Houston, Tex.) Vol. 59; no. 12; pp. 1096 - 1111
• Main Authors: Papavinasam, S., Revie, R.W., Attard, M., Demoz, A., Michaelian, K.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Houston, TX NACE International 01.12.2003; NACE
• Subjects: Analytical methods; Applied sciences; Control methods; Corrosion; Corrosion environments; Corrosion inhibitors; Corrosion prevention; Electrochemical impedance spectroscopy; Electrochemical noise; Electrochemistry; Electrode polarization; Exact sciences and technology; Gas pipelines; Inhibitors; Linear polarization; Metals. Metallurgy; Monitoring; Natural gas; Oil; Petroleum pipelines; Pipelines; Pitting (corrosion); Spectroscopy; Submarine pipelines; Weight loss; Gas pipeline; Corrosion; Check; Corrosion inhibition; Experimental study; Corrosion protection; Corrosion inhibitor; Pipeline
• ISSN: 0010-9312; 1938-159X
• DOI: 10.5006/1.3277529

ABSTRACTAddition of corrosion inhibitors is one of the common methods to control both general and pitting corrosion of oil and gas pipelines. Development of an integrity management program to control internal corrosion of such pipelines depends on our ability to monitor the efficiency of the inhibitor performance. Monitoring in an oil and gas pipeline is a complex process due to the multitude of conditions that exist in such an environment. In this paper, the reliability of weight loss, linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS), electrochemical noise (EN), and externally mounted hydrogen probes for monitoring inhibitor performance in oil and gas pipelines is investigated. INTRODUCTIONOil and gas pipeline flows are multiphase in nature, containing oil, aqueous (brine water), and gas phases. One of the main risks of operating such pipelines is internal corrosion, predominantly, pitting corrosion. By estimating conditions that cause corrosion, strategic decisions can be taken to control corrosion by, for example, adding corrosion inhibitors, adjusting inhibitor concentration, and/or adjusting fluid flow rate. Thus, monitoring corrosion in operating pipelines is an important step of the integrity management process. An ideal monitoring technique should provide data on the effect of inhibitors on both general and pitting corrosion. Since no one method could be used to provide all information, in general, a suite of methods are used to increase the reliability of the data. In using different monitoring techniques, the advantages and disadvantages of techniques should be understood, especially when the corrosion rates determined by different methods are used to develop integrity management programs. Numerous issues can make the task of extracting corrosion rates from the measured data a complex one whether the measurements are averaged (e.g., weight loss), instantaneous (e.g., linear polarization resistance [LPR] and electrochemical impedance spectroscopy [EIS]), or continuous (e.g., electrochemical noise [EN]).1-21 The present goal is to access the reliability of weight loss, LPR, EIS, EN, and externally mounted hydrogen probes for monitoring performance of corrosion inhibitors in operating oil and gas pipelines.