Pipe corrosion monitor

Claim 3

The method as defined in claim 1, wherein the step of measuring the transient decay of the charge comprises: (a) introducing into the soil a reference cell operable to produce a given reference voltage; and (b) connecting a measuring device between said reference cell and said object.

Claim 4

The method as defined in claim 2, wherein said reference cell is a copper/copper sulphate half cell.

Claim 5

The method defined in claim 2, and further including the preliminary steps of (a) periodically interrupting said current to produce off-current periods; and (b) determining by means of said measuring device when said object is charged to said given level.

Claim 6

Apparatus for measuring the amount of corrosion occuring since placement of a metallic object coated with a non-conductive, corrosion-resistant protective layer, said object being buried in situ in the soil, comprising: (a) an electrode adapted for insertion onto the soil adjacent said object; (b) a direct-current voltage source; (c) circuit means connecting said voltage source with said electrode and said object to establish a current path from said electrode to the object via the soil and at least one opening produced in the protective layer by the corrosion of a given area of the object, thereby electrically charging the object to a given level relative to electrical ground; (d) means for opening said circuit path after the charge in said object reaches a given level; and (e) means for measuring the transient decay of the charge, thereby providing an inducation of the amount of corrosion of the object occurring since placement.

Claim 7

Apparatus for measuring the amount of corrosion occuring since placement of a metallic object coated with a non-conductive, corrosion-resistant protective layer, said object being buried in situ in the soil, comprising: (a) an electrode adapted for insertion onto the soil adjacent said object; (b) a direct-current voltage source; (c) circuit means connecting said voltage source with said electrode and said object to establish a current path from said electrode to the object via the soil and at least one opening produced in the protective layer by the corrosion of a given area of the object, thereby electrically charging the object to a given level relative to electrical ground; (d) means for opening said circuit path after the charge in said object reaches a given level; and (e) means for measuring the transient decay of the charge, thereby providing an inducation of the amount of corrosion of the object occurring since placement.

Claim 8

Apparatus defined in claim 5, wherein said decay measuring means includes: (1) a reference cell inserted in the soil and operable to produce a given reference voltage; and (2) a measuring device connected between said reference cell and said object.

Claim 9

Apparatus defined in claim 6, wherein said reference cell is a copper/copper sulphate half cell.

Claim 10

Apparatus defined in claim 6, wherein said measuring device includes: (a) a voltmeter for measuring the charge on said object; and (b) a chart recorder for recording the charge on said object as a function of tune.

Claim 11

Apparatus defined in claim 6, and further including means for periodically interrupting said current to produce off-current periods during which the charge on the object is measured by said measuring device to determine when the charge reaches said given level.