| 摘要 |
<p>672,110. Electrolytic protection of immersed structures. DOW CHEMICAL CO. June 13, 1950 [June 15, 1949], No. 14786/50. Class 41. [Also in Group XVIII] An electrical system for the protection of a structure immersed in sea water and formed of a corrodible metal no more anodic than zinc, comprises a first-current self-exciting source consisting of a rapidly-expandable quantity of magnesium metal submerged in the sea water near the structure and connected electrically thereto, the quantity of metal having a surface area of at least 0.5 sq. feet per lb. and such mass as to correspond to at least 0.12 lb per sq. foot of structure to be protected, and a secondcurrent source also connected to the structure and of magnitude sufficient to provide a current corresponding to at least 0.002 amps per sq. ft. of structure for a period of at least a year. Preferably the second-current source is a slowly expandable quantity of magnesium metal having a surface area of less than 0.1 sq. ft. per lb. and of such mass as to correspond to at least 0.036 lb. per sq. ft. of structure being protected. As shown, a vertical steel pile bulkhead 6 immersed in sea water 7 has lengths of magnesium ribbon 8 attached at the top along the bulkhead and hanging down into the water. Each ribbon has a central core of steel wire and forms the first-current source. The secorid-current source is provided by stringing on and welding several magnesium anodes 11 to electrically-conducting cables 13 which are swung from eyebolts 15 mounted on brackets 16 welded to the pile 6 at intervals along its length. Each anode has a steel core welded to the cable. Specification 540,487 and U.S.A. Specification 2,200,469 are referred to.</p> |
