The United States of America as Represented by the Secretary of

Exxon Production Research Company

Felix N Kusenberger

William Dean Perry

Clifford W Petersen

Mark C Moyer

Cecil M Teller, Ii

George A Ferguson

John R Barton

Albert S Lozano

Wilson B Tarver, Jr

Floyd A Balter

A method of inspecting the reinforcing members in prestressed concrete beams by generating a magnetic field close to the beam and measuring the field by means of a Hall effect sensor located between the pole pieces of the magnet. A partial or total break in a reinforcing member produces an anomaly in the magnetic field, which in turn registers as a voltage 'spike' in the output of the Hall effect sensor. The method further includes a method for enhancing the data by substantially reducing or eliminating the effects of transverse reinforcing steel or support members located at the site of a break in the prestressed member.

Magnetic inspection of reinforcing steel rods in prestressed concrete

Magnetic inspection of reinforcing steel using sensor array

Apparatus for detecting flaws in the threaded end of a ferromagnetic pipe is disclosed. The apparatus comprises means for applying a magnetic force to produce a field generally axially through the threaded end of the pipe, first and second means adjacent successive crests of a thread for sensing a generally radial magnetic field and generating a first and second signal corresponding to the sensed magnetic fields, and means for differentially connecting the signals generated by said first and second sensing means, whereby a differential output signal is produced in response to a flaw between the crests of the thread being inspected. The apparatus also comprises means for helically rotating said sensing means to follow a path corresponding to the threads of the pipe, whereby the first and second signals vary with time. A method for detecting flaws in the threaded end of a ferromagnetic pipe is also disclosed. The method comprises the steps of applying a magnetic force to produce a field generally axially through the threaded end of the pipe, sensing the radial magnetic field adjacent successive crests of a thread of the pipe, generating first and second signals corresponding to the sensed magnetic fields, and differentially connecting the first and second signals.

Method and apparatus for detecting flaws in the threaded end of an

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San Antonio, TX, United States of America

Felix N Kusenberger