Method and apparatus for determining the location of a leak in a pipe buried underground

• US 4,101,827 A
• Filed: 12/17/1976
• Issued: 07/18/1978
• Est. Priority Date: 12/17/1976
• Status: Expired due to Term

• Current Assignee: Franklin F. Offner
• Original Assignee: Franklin F. Offner
• Inventors: Offner, Franklin F.
• Primary Examiner(s): Krawczewicz, Stanley T.
• Application Number:
  US05/751,891
• Time in Patent Office: 578 Days
• Field of Search: 324/65 P, 324/52, 324/65 R, 324/64, 340/242, 73/73, 200/61.05, 200/DIG. 40
• US Class Current: 324/693
• CPC Class Codes: G01M 3/18 for pipes, cables or tubes; for pipe joints or seals; for valves; for welds; for containers, e.g. radiators

Abstract

The location of one or more leaks in a pipe made from an electrically insulating material and which is buried in an electrically conductive medium, typically a pipe buried underground, is determined by filling the pipe with an electrically conductive fluid, e.g. tap water, passing an electrical current through the fluid in such manner as to establish a voltage gradient along the length of the fluid in the pipe and then analyzing the gradient to determine the location of the leak. In one embodiment, the bared end of an insulated conductor connected to one terminal of a voltmeter, the other terminal being grounded, is drawn through the pipe to measure the gradient. In another embodiment, a voltage source is connected to the fluid at opposite ends of the pipe to establish a voltage gradient for the distance between those ends, the voltage drop between the fluid at one end of the pipe and ground is measured and the distance from that end of the pipe to the leak point is determined by the relationship between these two voltages and distances.

Claims

1. The method for determining the location of a leak in a pipe made of an electrically insulating material which is buried in a medium that is electrically conductive which comprises the steps of:

at least partially filling the pipe with a fluid that is electrically conductive,

passing an electrical current through the fluid in said pipe;

measuring the electrical potential between said fluid and the medium in which said pipe is buried, and

ascertaining the location of the leak from the measured potential.

2. The method for determining the location of a leak in a pipe made of an electrically insulating material which is buried in a medium that is electrically conductive which comprises the steps of:

at least partially filling the pipe with a fluid that is electrically conductive,

establishing a voltage difference between the fluid in said pipe and said electrically conductive medium to establish a voltage gradient along the fluid, and

measuring the voltage incrementally along the gradient until a point where said gradient substantially changes in value is reached and which latter indicates the location of a leak.

3. The method for determining the location of a leak in a pipe made of an electrically insulating material which is buried in a medium that is electrically conductive which comprises the steps of:

at least partially filling the pipe with a fluid that is electrically conductive,

effecting a flow of electrical current through the fluid along the pipe and which establishes a corresponding voltage gradient, and

deriving the location of said leak by determination of the voltage drop across said fluid which occurs between a known point in the fluid and the medium in which said pipe is buried.

4. The method for determining the location of a leak in a pipe made of an electrically insulating material which is buried in a medium that is electrically conductive which comprises the steps of:

at least partially filling the pipe with a fluid that is electrically conductive,

applying a voltage between the fluid at one end of the pipe and said medium in which said pipe is buried thereby to effect a flow of electrical current through said fluid from said pipe end to the leak point and establish a voltage gradient therealong, and

measuring the voltage along said gradient in an incremental manner until a point where said gradient substantially changes in value is reached and which thereby is indicative of the leak point.

5. The method for determining the location of a leak in a pipe made of an electrically insulating material which is buried in medium that is electrically conductive which comprises the steps of:

at least partially filling the pipe with a fluid that is electrically conductive,

applying a voltage between the fluid at one end of the pipe and said medium in which said pipe is buried thereby to effect a flow of electrical current through said fluid from said pipe end to the leak point and establish a voltage gradient therealong, and

moving a voltage measuring probe through the fluid from one end until a point where said gradient substantially changes in voltage is reached and which thereby indicates a leak point in said pipe.

6. The method for determining the location of a leak in a pipe made of an electrically insulating material which is buried in a medium that is electrically conductive which comprises the steps of:

at least partially filling the pipe between the ends thereof with a fluid that is electrically conductive,

applying a voltage V₁ to the fluid at the opposite ends of said pipe thus to effect a flow of electrical current through the fluid and establish a voltage gradient therealong for the distance d₂ between the pipe ends,

measuring the voltage drop V₂ between the fluid at one end of said pipe and the medium in which said pipe is buried, and

determining distance of d₁ from said one end of said pipe to the leak point from the relationship

space="preserve" listing-type="equation">d.sub.1 d.sub.2 = V.sub.1 /V.sub.2.

7. The method of determining the location of a plurality of leaks in a pipe made of electrically insulating material which is buried in a medium which is electrically conductive, which comprises the steps of:

at least partially filling the pipe with a fluid that is electrically conductive,

applying a voltage between the fluid at one end of the pipe and said medium in which said pipe is buried thereby to effect a flow of electrical current through said fluid from said pipe end to said medium through the plurality of leak points, and thus to establish voltage gradients along the fluid in said pipe, and

measuring the voltage along said gradients in an incremental manner, thus determining the points at which changes in said gradients occur and which is thereby indicative of the various points of leak.

8. Means for determining the distance along an insulating pipe at which a leak or leaks to ground occurs, including

an insulated flexible wire which may be inserted into one end of said pipe, said wire having a portion of each end electrically exposed,

a first electrode immersed in conducting fluid at least partially filling said pipe,

a second electrode connected to ground,

a source of voltage connected between said first and second electrodes,

a voltage measuring means, connected to measure the voltage between said wire and ground, and

means for passing said wire in incremental and known distances through said pipe.

9. Means for determining the position in a buried insulating pipe at which a leak to ground occurs, including,

a source of voltage,

a first and second electrode connected to said source, said electrodes being immersed in electrically conductive fluid at least partially filling said pipe, respectively at the two ends of said pipe, thus producing a voltage gradient through said fluid,

voltage measuring means connected to alternatively measure the total voltage difference across the fluid at the two ends of said pipe, and the voltage between the fluid at one end of said pipe and ground, thus permitting determination of the position of a leak.

10. Means as described in claim 9, which further includes adjusting means so that said measuring means may read the position of the leak directly.