A new technique for lead cable sheathing

A new technique used in the production of lead sheaths for electric power cables is introduced. The various phases of the problem and the difficulties encountered heretofore are described. It has been found that it is necessary to consider the problem both as a mechanical and a chemical one. A method is described in which both factors are used. This consists in pretreating lead as received with a sodium-lead alloy to remove all deleterious impurities and the use of a special standpipe procedure for filling the lead-press extrusion cylinder to obtain a complete union of successive charges, resulting in sound lead sheaths throughout the entire cable length. Test data show that the physical and corrosion properties of lead are not adversely affected by the sodium treatment.