CORROSION PATENTS

Tanker linings. Concrete mixes may be used as anti‐corrosion protective coatings on steel surfaces, especially in oil tanker holds. These latter are alternately filled with ballast sea water and crude oil, which raises a severe corrosion problem. Emulsified polyvinyl acetate in concrete is found to be corrosion‐resistant for this purpose, and sufficiently flexible to withstand the ship's vibration. A good formulation is one to three parts of aggregate to one part of cement, with 0.07 to 0.22 of polyvinyl acetate, and all gauging water being supplied by the emulsion if required. This mix is found to have good adhesion to steel when applied at one to three‐sixteenths inch thickness, either by trowel or spray. Preferably the metal surface is scale‐free, and the aggregate largely devoid of dust, and it is carefully pointed out that this specification concerns lime cements, whereas B.P. 666,865, an earlier but otherwise similar one, relates to alumina cements.—Brit. Pat. 732,110, Vinyl Products Ltd., Surrey.