Effective protection of the interior surface of these pipelines is difficult, and ordinary anti‐corrosive measures are for the most part inapplicable and/or too costly. The method used here is that of anodic passivation with permanganate of potassium and has, in fact, been fairly successfully adopted, e.g. in France, as described by J. Changarnier (Corrosion et Anti‐Corros., 1953, 1 (1), 8). The nature of the corrosion—and also erosion—of these pipelines by sea‐water flow is discussed, and a simple set‐up for simulating actual conditions in the laboratory is described. The tests included, per day, 7 hr. exposure to flowing sea water and 17 hr. exposure to still water and were increased to 24 hr. at the end of each week of the test, spanning a total period of 100 days. The strength of permanganate solution (in soft water) was 150 p.p.m. Graphed results demonstrate that the untreated control pipe showed corrosion penetration of 0.03 mm. at the end of 100 days, whilst in the treated pipe, penetration was no more than about 0.006 mm.
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