| 摘要 |
1,220,166. Laying pipes. ALLEN INTERNATIONAL Inc. 30 Aug., 1968 [5 Sept., 1967], No. 41547/68. Heading F2P. A method of determining the presence and location of an element, e.g. a conduit, sewer pipe, wire, cable &c., disposed beneath the surface of the earth includes the steps of digging a trench in the earth placing an element, and an overlying rupturable coloured body therein, the rupturable body comprising a sheet, or tape, of a flexible metal foil having a thickness in the range of from 0À0005 to 0À004 inch and carrying an adherent moisture and soil resistant coating, e.g. a pigmented paint coated with a film of synthetic plastics, such as transparent polyethylene, on at least one surface thereof. The foil, which may be made, e.g. of copper, aluminium, nickel or tin but which is preferably formed of steel, is preferably from 0À001 to 0À002 inch thick made by further cold rolling a conventional tin-coated, mill gauge, cold roll steel, which preferably should not be annealed. The steel foil can be imprinted with any desired indicia, and film of coloured polyethylene, or polypropylene, can be initially imprinted and then laminated on to opposite sides of a steel foil.
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