Technical Papers & Special Features
Over the past 35 years, Corrosion Testing Laboratories has performed research and written papers on many issues for various industries. CTL Personnel have been primary authors, co-authors, and presenters of this work with the goal technical progress. Some of these papers and presentations are shared below.
Formicary Corrosion is considered a significant problem in the air-conditioning industry. Approximately 10% of all preliminary failures of copper tubes in the HVAC industry are a direct result of formicary corrosion on a worldwide scale. Some manufacturers are detecting the localized formicary corrosion in new tubes as well as tubes with less than one year of service.
Much has been learned over a short period of time with respect to the corrosion assessment of small medical implant devices. Laboratory testing started with modifications of ASTM G 5 and G 61, which lead to the development of ASTM F 2129, and thence the fine-tuning of that specification to meet the intent of the FDA Guideline for non-clinical tests. The changes in electrochemical testing protocol with time are reviewed. Comparative data is presented addressing test environments, scan rates, statistical replication, alloy response, and acceptance criteria.
Rouging (discoloration) of stainless steel is a problem most chronic in the pharmaceutical industry. Interior surfaces of high purity water units such as distillation units, storage tanks, process vessel, etc are the areas where rouging is most likely to occur. Rouging is a thin film, usually reddish-brown or golden in color, of iron oxide or hydroxide, typically found on stainless steels.
Problems in Utilizing ASTM G 48 to Evaluate High -Alloy Stainless Steels
The ASTM G 48 test evaluates an alloys resistance to pitting and crevice corrosion using severe test conditions. Unlike most other ASTM standards, which are cut and dry in their test procedures, this standard has loopholes, which allows test-to-test and laboratory-to-laboratory variation, which makes comparison of data difficult. Modifications are often used to improve the standard, but these are not adopted universally.
Indoor corrosion failures of aluminum-finned copper-tube evaporator coils, and also in some systems without aluminum fins, is a menacing issue in the heating, ventilation, and air conditioning (HVAC) industry. Extensive laboratory testing has verified the development of a reproducible screening method to assess suspected contaminants of producing premature failures of copper tube resulting from a very localized form of corrosion known as “formicary corrosion” [a/k/a “ant nest corrosion”]. This paper provides a historical perspective on formicary corrosion and various mechanisms.
Corrosion Control Design Considerations for a New Well Water Line
An impressed current cathodic protection (ICCP) system was recently installed to provide corrosion control protection for approximately 2 miles (3.2 kilometers) of underground, direct buried ductile iron piping at the Savannah River Plant (SRP). The piping system serves well water pumps and delivers the water from two newly installed water wells to the main plant area for potable and domestic water use.Extensive detailed testing was performed along the proposed route of the pipeline. This was required to gather the engineering data necessary to establish soil characteristics and the specific requirements for such a corrosion control system. The results of the testing, the design options which were evaluated, the problems encountered during construction, and the effectiveness of the installed system are discussed.