Abstract: A method for detecting breaks in a prestressed wire, rod or bar in prestressed concrete pressure pipe (PCCP), embedded in concrete and/or mortar is described. A remote field eddy current exciter/transformer coupling probe is traversed axially internally through the PCPP so as to create an energy flow path within and external to the wall of the PCPP and to induce a transformer coupling from the prestressing winding thus generating a signal in a detector spaced from and usually approximately coplanar with the exciter. As the exciter traverses a break in the wire, rod or bar, a small signal change is generated in the detector, nearly regardless but not independent of the radial position of the detector relative to the break.

Abstract: A method for detecting breaks in a prestressed wire, rod or bar in prestressed concrete pressure pipe (PCCP), embedded in concrete and/or mortar is described. A remote field eddy current exciter/transformer coupling probe is traversed axially internally through the PCPP so as to create an energy flow path within and external to the wall of the PCPP and to induce a transformer coupling from the prestressing winding thus generating a signal in a detector spaced from and usually approximately coplanar with the exciter. As the exciter traverses a break in the wire, rod or bar, a small signal change is generated in the detector, nearly regardless but not independent of the radial position of the detector relative to the break.

Abstract: A method for detecting breaks in a prestressed wire, rod or bar embedded in concrete surrounding a metal pipe is described. A remote field eddy current probe is traversed axially internally through the pipe so as to create an energy flow path externally of the pipe and a transformer coupling through the pipe, and generate a signal in a detector coil axially spaced from an exciter coil. As the exciter coil traverses the wire, rod or bar containing the break a signal change is generated, regardless of the radial position of the detector coil relative to the break.

Abstract: A method and apparatus for determining position size and shape of defects in a bundle of heat exchanger tubes are described. An AC current exciter coil is placed in one tube and a detector coil is placed in an adjacent tube. This configuration of exciter and detector coils reduces the blind spot effect caused by interference by tube support plates and allows the inspection multiple or finned heat exchanger tubing.