Method and apparatus generating and detecting torsional wave inspection of pipes or tubes
First Claim
1. In a method for nondestructive inspection of a pipe or tube for anomalies therein, which anomalies can indicate defects such as notches, cuts, cracks, wear or corrosion, using magnetostrictive techniques, of the type which include inducing residual magnetization in at least one thin ferromagnetic strip;
- circumferentially pressing said thin ferromagnetic strip against said pipe or tube;
first locating a transmitter coil adjacent said thin ferromagnetic strip;
second locating a receiver coil adjacent said thin ferromagnetic strip;
generating a pulse signal in a transmitter control circuit and delivering it to said transmitter coil, said transmitter coil creating magnetostrictively a guided wave in said thin ferromagnetic strip, said thin ferromagnetic strip being coupled to said pipe or tube so that said guided wave propagates along the length of said pipe or tube;
generating and delivering a pulse signal;
magnetostrictively detecting by said receiver coil said guided wave and any reflected signals in said pipe or tube through said coupled thin ferromagnetic strip, said reflected signals including any caused by said anomalies in said pipe or tube; and
determining if said reflected signals were due to said anomalies that should not exist in said pipe or tube, wherein the improvement comprises;
said thin ferromagnetic strip being made from an iron-cobalt alloy.
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Accused Products
Abstract
A method and apparatus is shown for implementing magnetostrictive sensor techniques for the nondestructive evaluation of pipes or tubes. A magnetostrictive sensor generates guided waves in a pipe or tube, which waves travel therethrough in a direction parallel to the longitudinal axis of the pipe or tube. This is achieved by using a magnetized ferromagnetic strip being pressed circumferentially against the pipe or tube. For improved efficiency, the strip may be made from an iron-cobalt alloy. The guided waves are generated in the strip and coupled to the pipe or tube and propagate along the length of said pipe or tube. For detection, the guided waves in said pipe or tube are coupled to the thin ferromagnetic strip and are detected by receiving MsS coils. Reflected guided waves may represent defects in the pipe or tube.
47 Citations
22 Claims
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1. In a method for nondestructive inspection of a pipe or tube for anomalies therein, which anomalies can indicate defects such as notches, cuts, cracks, wear or corrosion, using magnetostrictive techniques, of the type which include inducing residual magnetization in at least one thin ferromagnetic strip;
- circumferentially pressing said thin ferromagnetic strip against said pipe or tube;
first locating a transmitter coil adjacent said thin ferromagnetic strip;
second locating a receiver coil adjacent said thin ferromagnetic strip;
generating a pulse signal in a transmitter control circuit and delivering it to said transmitter coil, said transmitter coil creating magnetostrictively a guided wave in said thin ferromagnetic strip, said thin ferromagnetic strip being coupled to said pipe or tube so that said guided wave propagates along the length of said pipe or tube;
generating and delivering a pulse signal;
magnetostrictively detecting by said receiver coil said guided wave and any reflected signals in said pipe or tube through said coupled thin ferromagnetic strip, said reflected signals including any caused by said anomalies in said pipe or tube; and
determining if said reflected signals were due to said anomalies that should not exist in said pipe or tube, wherein the improvement comprises;
said thin ferromagnetic strip being made from an iron-cobalt alloy. - View Dependent Claims (2, 3, 4, 5)
- circumferentially pressing said thin ferromagnetic strip against said pipe or tube;
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6. In an apparatus for the nondestructive inspection of a pipe or tube for anomalies therein, which anomalies indicate defects such as notches, cuts, cracks, wear or corrosion, using magnetostrictive techniques, of the type wherein at least one thin ferromagnetic strip has residual magnetization therein, said thin ferromagnetic strip being circumferentially pressed against said pipe or tube;
- a transmitter coil is located adjacent said thin ferromagnetic strip;
a receiver coil is located adjacent said thin ferromagnetic strip;
a transmitter control circuit is connected to said transmitter coil for generating a pulse signal and delivering said pulse signal to said transmitter coil, said transmitter coil creating magnetostrictively a guided wave that is coupled from said thin ferromagnetic strip to said pipe or tube to propagate along the length of said pipe or tube;
wherein said receiver magnetostrictively detects said guided wave and any reflected signals, including any caused by said anomalies in said pipe or tube; and
said transmitter coil and said receiver coil are wound adjacent said thin ferromagnetic strip so that said guided wave moves perpendicular thereto, wherein the improvement comprises;
said thin ferromagnetic strip being made from an iron-cobalt alloy. - View Dependent Claims (7, 8, 9, 10, 11, 12)
- a transmitter coil is located adjacent said thin ferromagnetic strip;
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13. A method for nondestructive inspection of a 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:
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inducing residual magnetization in at least one thin iron-cobalt alloy strip;
circumferentially pressing said thin iron-cobalt alloy strip against said pipe or tube;
first locating a transmitter coil adjacent said thin iron-cobalt alloy strip;
second locating a receiver coil adjacent said thin iron-cobalt alloy strip;
generating a pulse signal in a transmitter control circuit and delivering said pulse signal to said transmitter coil, said transmitter coil creating magnetostrictively a guided wave in said thin iron-cobalt alloy strip, said thin iron-cobalt alloy strip being coupled to said pipe or tube so that said guided wave propagates along the length of said pipe or tube;
magnetostrictively detecting by said receiver coil said guided wave and any reflected signals in said pipe or tube through said coupled thin iron-cobalt alloy strip, said reflected signals including any caused by said anomalies in said pipe or tube and said signal amplitude of said reflected signals being at least four times greater than with coupled nickel strips; and
determining if said reflected signals were due to said anomalies that should not exist in said pipe or tube. - View Dependent Claims (14, 15, 16)
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17. An apparatus for the nondestructive inspection of a pipe or tube for anomalies therein, which anomalies indicate defects such as notches, cuts, cracks, wear or corrosion, using magnetostrictive techniques, said apparatus comprising:
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at least one thin iron-cobalt alloy strip that has residual magnetization therein, said thin iron-cobalt alloy strip being circumferentially pressed against said pipe or tube;
a transmitter coil located adjacent said thin iron-cobalt alloy strip;
a receiver coil located adjacent said thin iron-cobalt alloy strip;
a transmitter control circuit connected to said transmitter coil for generating a pulse signal and delivering said pulse signal to said transmitter coil, said transmitter coil creating magnetostrictively a guided wave that is coupled from said thin iron-cobalt alloy strip to said pipe or tube to propagate along the length of said pipe or tube;
said receiver magnetostrictively detecting said guided wave and any reflected signals, including any caused by said anomalies in said pipe or tube, said signal amplitude of said reflected signals being at least four times greater than with coupled nickel strips;
said transmitter coil and said receiver coil being wound adjacent said thin iron-cobalt alloy strip so that said guided wave moves perpendicular thereto. - View Dependent Claims (18, 19, 20, 21, 22)
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Specification