US 4,949,076 AGranted

Apparatus for detecting and locating leakage in underwater structures

AssigneeConoco Inc.

InventorLaymond D. Wann

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Abstract

A system for leak detection in underwater structures wherein each critical leakage test point is maintained dry by an enclosure and a test cable is led down through the series of enclosures in fluid-tight manner to support a test probe within the dry test point volume. The test cable is a coaxial cable of selected characteristic impedance and each probe consists of a spirally wound, open-end dual pair supported on a plastic stub so as to constitute a parallel resonant circuit at a selected frequency. Thereafter, a test pulse is conducted down the coaxial cable and the impedance of any probe will be altered by the presence of water to produce a reflected pulse back up the coaxial cable to be detected and input to gating and counting circuitry to determine signal travel duration and, therefore, distance along the cable, as processing, printing and readout components provide output indications.

Claims10

Dependent claims

A system for monitoring integrity of underwater structures, comprising:

at least one enclosure member sealingly secured over at least one selected area of the underwater structure, each enclosure member maintaining a dry void;
a coaxial cable having a central conductor and centric shield, and having an input above water and extending down through said at least one enclosure member in water-tight passage, said cable terminating in characteristic resistance and water-tight enclosure;
a least one probe having a segment of insulative rod material and a pair of generally equi-spaced wires wound helically on said segment in one direction and reverse wound in overlap to terminate in an open end, and connected between the cable central conductor and shield and being disposed in each at least one dry void, said probe being wound to function as a parallel inductance and capacitance circuit that is resonant at a preselected frequency;
means generating a pulse having said preselected frequency as the fundamental frequency applied as said input to the coaxial cable;
and
means detecting any reflected pulse on said coaxial cable.

3 more elements

Dependencies are inferred from the claim text.