Method and apparatus generating and detecting torsional waves for long range inspection of pipes and tubes
AssigneeSouthwest Research Institute
InventorsHegeon Kwun, Sang-Young Kim, Alfred E. Crouch
Life of this patent
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Abstract
A method and apparatus is shown for implementing magnetostrictive sensor techniques for the nondestructive evaluation of ferromagnetic pipes or tubes. A magnetostrictive sensor generates shear waves and/or torsional waves in ferromagnetic pipes or tubes, which waves travel therethrough in a direction parallel to the longitudinal axis of the pipe. A circumferential magnetization is generated in the ferromagnetic pipe or tube by a DC or low frequency voltage establishing a current along the longitudinal axis and past the magnetostrictive sensor. Reflected shear or torsional waves may represent defects in the pipe or tube.
Claims14
A method for nondestructive inspection of a ferromagnetic pipe or tube for anomalies therein, which anomalies can indicate defects such as notches, cuts, cracks, wear or corrosion, using magnetostrictive techniques, said method comprising the following steps:
- first locating a transmitter adjacent to said ferromagnetic pipe or tube;
- second locating a receiver adjacent to said ferromagnetic pipe or tube;
- inducing a bias magnetic field in the circumferential direction around said ferromagnetic pipe or tube;
- generating a pulse signal in a transmitter control circuit and delivering said pulse signal to said transmitter, said transmitter creating magnetostrictively a torsional wave in said bias magnetic field which propagates along said ferromagnetic pipe or tube;
- detecting magnetostrictively by said receiver said torsional wave and any reflected signals, including those caused by said anomalies in said ferromagnetic pipe or tube;
- and
- determining if said reflected signals were due to anomalies that should not exist in said ferromagnetic pipe or tube;
- said transmitter and said receiver having a coil wound adjacent said ferromagnetic pipe or tube so that said torsional wave moves perpendicular thereto and along the length of said ferromagnetic pipe or tube.
An apparatus for the nondestructive inspection of a ferromagnetic pipe or tube for anomalies therein, which anomalies indicate defects such as notches, cuts, cracks, wear or corrosion, using magnetostrictive techniques comprising:
- a transmitter located adjacent said ferromagnetic pipe or tube;
- a receiver located adjacent said ferromagnetic pipe or tube;
- inducer for setting up a bias magnetic field in the circumferential direction around said ferromagnetic pipe or tube, said bias magnetic field being adjacent said transmitter and said receiver;
- a transmitter control circuit connected to said transmitter for generating a pulse signal and delivering said pulse signal to said transmitter, said transmitter creating a torsional wave that moves lengthwise along said pipe or tube;
- said receiver detecting magnetostrictively said torsional wave and any reflected signals, including those caused by said anomalies in said ferromagnetic pipe or tube;
- said transmitter and said receiver having coils wound adjacent said ferromagnetic pipe or tube so that said torsional wave moves perpendicular thereto and along the length of said ferromagnetic pipe or tube.
Dependencies are inferred from the claim text.