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US 5,331,286 AGranted
Method for continuously monitoring the soundness of the protective covering on underground metal structures, and devices for its implementation
AssigneeEniricerche S.p.A.
InventorsLuigi Rivola, Sebastiano Di Liberto
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Abstract
A method for monitoring the soundness of the protective covering on underground metal structures subjected to cathodic protection, based on the electrical resistance offered by said covering, and consisting of modulating the imposed cathodic protection current and measuring the corresponding variation in potential due to the ohmic drop, said resistance being obtained from the ratio of the variation in potential to the modulation current.
Claims6
A method for continuously monitoring the soundness of a protective covering on an underground or immersed metal conduit subjected to cathodic protection, comprising:
- a. modulating the cathodic protection current applied to the conduit with substantially square waves, wherein said modulation is effected symmetrically at a level of modulation below 10%;
- b. directly measuring the potential variation due to the ohmic drop .DELTA.V* induced in the conduit by said applied modulation current I*;
- and
- c. determining the resistance offered by the covering by the relationship R=.DELTA.V*/I*, wherein the monitoring is effected continuously by permanently modulating the cathodic protection current imposed on the conduit and wherein the resistance is measured with the IR drop so that changes in the soundness of the protective covering of the conduit can be detected.
1 more element
Dependencies are inferred from the claim text.