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Selecting Pipeline Corrosion Inhibitors in the Laboratory

A half-day workshop “Evaluating and Qualifying Oilfield and Refinery Corrosion Inhibitors in the Laboratory” is being offered by ASTM Committee G01 on Corrosion of Metals, 8 a.m., Wed., Nov. 7, in Dallas, Texas, during their general meetings. There is no admission fee but pre-registration is desired. The event is part of an ongoing effort by ASTM to promote the use of state-of-the-art techniques for selection of inhibitors by the oilfield and refinery industries. Following the workshop, all are invited to attend a meeting on corrosion inhibitors at 1 p.m. with ASTM G01.05.11.01.

The workshop will highlight ASTM G 170, Standard Guide for Evaluating and Qualifying Oilfield and Refinery Corrosion Inhibitors in the Laboratory, just approved in May 2001. Developed by oil companies, inhibitor suppliers, researchers, consultants, and educators in ASTM Subcommittee G01.05 on Laboratory Corrosion Tests, the standard promotes:

• Selection of cost-effective, high-quality inhibitors for companies; and
• Design and manufacture of more efficient products by suppliers.

“Oil and gas pipelines are vulnerable to corrosion,” explained Sankara Papavinasam, Ph.D., a research scientist with CANMET Materials Technology Laboratory, Ontario, Canada, who helped to develop ASTM Standard G 170.

“Corrosion results, in part, from the use of carbon and low-alloy steels in pipeline construction, which, although cost-effective, characteristically exhibit poor corrosion resistance. The industry’s response has been to introduce corrosion inhibitors, primarily in upstream pipelines carrying oil and gas from fields to processing plants. The problem is that no single inhibitor suits all situations. The effectiveness of an inhibitor is determined not only by the properties of the gas and liquid contents of the pipeline and by the properties of the inhibitor itself, but also by the means by which it is added to the pipeline and by the operating conditions of the system, such as temperature, flow rate and pressure. The annual inhibitor market in North America alone is about $1.2 billion.

“Selecting the appropriate inhibitor for a particular oil/gas mixture and determining optimum use in the various delivery systems are the key challenges facing the industry,” he continued. “In selecting an appropriate inhibitor for a particular application, several factors are considered, including the efficiency of inhibitor, water/oil partitioning, solubility, emulsification tendency, foam tendency, thermal stability, toxicity, and compatibility with other additives/materials.”

Papavinasam noted that the new ASTM standard describes three methodologies that evaluate efficiency of inhibitors in the laboratory: rotating cylinder electrode, rotating cage, and jet impingement. Compact, inexpensive, hydrodynamically characterized, and scalable, they can be carried out under various flow conditions. With these methodologies, several variables that influence inhibitor performance in the field can be simulated, including composition (of the steel, brine, oil, and gas), temperature, pressure, and flow.

Also described in Standard G 170 are laboratory methods to evaluate other inhibitor properties including water/oil partitioning, solubility, emulsion, toxicity, foaming tendency, and thermal stability.

For workshop information, contact Sankara Papavinasam, Ph.D., CANMET Materials Technology Laboratory, Ontario, Canada (phone: 613/947-3603), or Milan Bartos, Ph.D., Ondeo Nalco Energy Services, L.P., Sugarland, Texas (phone: 281/263-7985). To learn more about Committee G01, contact staff manager Bruce Noe, ASTM (phone: 610/832-9719). //

Copyright 2001, ASTM