Transient electromagnetic method for directly detecting corrosion on conductive containers

Patent 4839593 Issued on June 13, 1989. Estimated Expiration Date:

December 17, 2007. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

3229197

3315155

3532969

3707672

3745452

Method for generating the eddy current signature of a flaw in a tube proximate a contiguous member which obscures the flaw signal
Patent #: 4194149
Issued on: 03/18/1980
Inventor: Holt , et al.

Apparatus and method for eddy current detection of subsurface discontinuities in conductive bodies
Patent #: 4271393
Issued on: 06/02/1981
Inventor: Hansen , et al.

Magnetic method and apparatus for measuring wall thickness
Patent #: 4418574
Issued on: 12/06/1983
Inventor: Flournoy

Coil apparatus mounted on an axially split spool for indicating wall thickness variations of a length of ferromagnetic pipe
Patent #: 4611170
Issued on: 09/09/1986
Inventor: Stanley , et al.

Coin discriminating apparatus using coil pulses of different lengths Patent #: 4717006
Issued on: 01/05/1988
Inventor: Chapman , et al.

Inventor

Spies, Brian R.

Assignee

Atlantic Richfield Company

Application

No. 07/133952 filed on 12/17/1987

US Classes:

324/240, Material flaw testing324/71.2Erosion

Examiners

Primary: Strecker, Gerard R.

Attorney, Agent or Firm

International Class

G01N 17/00 (20060101)

Abstract

There is disclosed a method for directly detecting corrosion on the walls of conductive containers wherein a transmitting antenna induces a current into a portion of the container wall and the decay of the induced current is detected by a receiving antenna, with a record of the decay of the induced current being created. The record is interpreted to determine the presence or absence of a corrosion component, with the corrosion component being caused by the presence of corrosion products having superparamagnetic properties.