Patents by Inventor David D. Stephen

David D. Stephen has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Yield strength determination of ferromagnetic materials
    Patent number: 4335352
    Abstract: This invention pertains to two forms of verifier of the grade of oil field tubular goods. The first form can be thought of as a sorter in that it will indicate when a particular length of tubular goods is of a different grade than its companions in a lot. The second form will identify the grade of a length. Both forms depend upon magnetizing or inducing magnetic eddy currents in the pipe which are detected and handled by the invention circuitry to sort or to identify.
    Type: Grant
    Filed: December 12, 1979
    Date of Patent: June 15, 1982
    Assignee: Homco International Inc.
    Inventor: David D. Stephen