Alternating voltage method of electrically detecting damage to an enamel layer having one or more tantalum plugs

Claim 1

Method of electrical detection of faults in an anticorrosion enamel layer of a metallic structure of an apparatus containing an electrically conducting medium and provided with at least one tantalum plug, comprising: providing an insulated tantalum electrode in said medium in electrical contact therewith together with connection means, insulated from said apparatus, for connecting said tantalum electrode to a potential source external to the portion of said apparatus containing said medium; applying a low voltage alternating potential between said tantalum electrode and said metallic structure while said medium is contained in said apparatus both to assure the coating of said tantalum electrode and of said tantalum plug(s) with a passivating layer and to furnish current for detection of faults in said enamel layer, and measuring the current flow produced by said application of potential after said tantalum electrode and said tantalum plug(s) have been coated with said passivating layer, thereby to determine the presence of a fault in said enamel layer, the frequency of said alternating potential being chosen so as to favor measurement of said current flow without substantial interference from extraneous electric-current-inducing fields.