Experimental study of one-step economical retarded sandstone acid

The objective of this study is to experimentally evaluate a new acid combination of HEDP: CH3COOH as a retarded acid to minimize some limitations of high-temperature sandstone acidizing, such as fast acid-rock reaction and secondary precipitation pipeline corrosion. In this work, the acid–base titration, core-powder solubility test, scale deposition test, corrosion rate measurement and corefloods were carried out to evaluate the performances of the acid combination, including acidity characteristics, retarded performance, preventing scale rate, corrosivity and improving permeability. And then the microstructure and mineral content in sandstone samples were observed and analyzed with SEM–EDS. The results of evaluation tests indicated that the new acid combination has excellent performances on retarded rate, preventing scale deposition, permeability enhancement and lower corrosivity, comparing with conventional mud acid. The results of SEM and EDS showed that the microstructure and mineral content of sandstone changed after acid treatment. Compared with mud acid, the new acid system can react more with small particles on sandstone surface and less with the skeleton of samples and the decrease in the contents of Mg, Al, Na, K, Ca and Fe is relatively lower.

Refining the use of oxygen consumption as a proxy corrosion rate measure for archaeological and historic iron

Since its introduction to the field of heritage science, oxygen consumption has found multiple applications in the assessment of artefact stability and the examination of conservation treatment efficiencies. Early papers identified various factors affecting oxygen measurements and produced preliminary data on their effects. This paper follows on from the early research by other workers and presents guidance on the application of oxygen consumption as a proxy corrosion rate measurement based on a decade of experience at Cardiff University. It examines the rationale for key aspects of the Cardiff protocols for oxygen consumption and presents data to underpin these. Finally, it provides instructional guidance for heritage scientists adopting oxygen consumption for their research applications.

Corrosion rate measurement for steel sheets of a fuel tank shell being in service

Some corrosion progress trends specific for cylindrical steel shells of typical above-ground fuel tanks are first identified experimentally and then quantitatively compared with one another. The inference is based on many random thickness measurements related to the selected corrosively weakened coating sheets and carried out at various moments of the tanks in question service time. It is shown in detail that in this type of structures, due to the manner of their use and, particularly, the material stored inside, the corrosion process is in general significantly accelerated over time. For this reason, a nonlinear formal model describing the simulated corrosion development anticipated for the future fuel tank service time seems to be the best choice in forecasting its remaining time to failure.