Dynamic corrosion tests were carried out on a curved mild-steel pipe through which hydrochloric acid-solution was circulated at a constant velocity.
As a result, it was recognized that the corrosion behavior of a curved pipe depended largely upon the property of its hardened surface-layer produced by cold-working. And, a method was proposed to estimate the corrosion allowance or the lifetime of a pipe under a given operating condition.

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Assuming that chemisorption plays a principal role in inhibition of high molecular-weight amine-type corrosion inhibitors, they firstly act as dehydrater pulling off water which is strongly adsorbed on metal surface, and secondly, occupy the spots produced by departure of the adsorbed water and form inhibitor film on the surface to prevent corrosion. Since functional atoms of polar group of these inhibitors can easily donate unshared electron pairs to hydrogen atoms of the adsorbed water, they can displace the water from the surface by hydrogen-bonding.
They can then be adsorbed by donating unshared electron-pairs to the electron-poor metal surface which resulted from the desorption of water. This study was undertaken to discuss relation between the desorption of water and the chemisorption of inhibitors. Reduced iron powder was previously filmed with N, N-dimethyl cetyl amine as an inhibitor in its carbon tetrachloride solution and then the filmed powder was dipped in uninhibited aq. solution of HCl. Inhibition efficiency was obtained by volume measurement of hydrogen evolved from the powder. During the filming, amount of water which was removed from iron powder and remained in the solution was determined by infrared spectrum measurement.
It was found that the amount of removed water was very closely related to the inhibition efficiency of the inhibitor-film on the surface of iron powder. The removed water can hardly be re-adsorbed on the metal surface as it is attracted by the inhibitor or other removed water in the solution. Amine inhibitors act as the effective filming agents and also as the effective dehydraters and result in good inhibition for metallic corrosion.

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