Abstract: A method and apparatus for determining the extent of axially extending defects in ferromagnetic elements, such as tubing comprising a continuous string for use in an oil or gas well is disclosed. The tubing trip tool detects axial defects, such as sucker rod wear during removal of the tubing from the well. A saturating magnetic field and a fluctuating magnetic field are applied to the tubing and the magnitude of the induced fields and the changes are measured to quantify defects in the tubing.

Abstract: A method and apparatus for determining the extent of defects in ferromagnetic tubular elements comprising a continuous string for use in an oil or gas well is disclosed. The tubing trip tool measures tubing average wall thickness, local defects, such as corrosion pitting, and axial defects, such as sucker rod wear during removal of the tubing from the well. Tubing velocity is also measured, and couplings between tubing sections are detected and counted, in order to specify the axial location of defects on each tube, and also provide a profile of the condition of the overall string. A saturating magnetic field and a fluctuating magnetic field are applied to the tubing and the magnitude of the induced fields and the changes are measured to quantify defects in the tubing.

Abstract: A method and apparatus for determining the extent of defects in ferrogmagnetic elements, such as tubing comprising a continuous string for use in an oil or gas well is disclosed. The tubing trip tool measures the depth of local defects, such as corrosion pitting, during removal of the tubing from the well. Tubing velocity is also measured, and couplings between tubing sections are detected and counted, in order to specify the axial location of defects on each tube, and also provide a profile of the condition of the overall string. A saturating magnetic field is applied to the tubing and a comparison of two derivatives of flux leakage is made to quantify defects in the tubing.

Abstract: A tubing trip tool for use in determining the extent of defects in tubular elements comprising a continuous string used in a subterranean oil or gas well during removal of the string from the well is disclosed. Local defects and axially extending defects, as well as the average wall thickness of the tubular elements, are measured. The position of the defects is determined by measuring the variable velocity of the tubular elements as they are removed from the well and by detecting end couplings having a larger cross-sectional area and the direction in which the end couplings are moving. A string profile of the position of the defects in the continuous string can also be established.

Abstract: A method and apparatus are provided for effecting the inspection of a ferromagnetic element, or piping, and particularly piping that is already installed. The invention incorporates a device for indicating wall thickness of a length of the ferromagnetic element, including means for producing a value of magnetic flux extending longitudinally through a portion of the element. A voltage generating device is disposed in surrounding relationship to the element and is movable axially relative to the length of the element containing the value of the magnetic flux. Means for indicating the voltage generated in the voltage generating means by the value of the magnetic flux also are provided. Preferably, an axially split spool is provided which may be closed in surrounding relationship to an installed pipe. A saturation level of magnetic flux is induced in the pipe by a flexible cable which is wrapped around the spool in a multi-turn configuration and supplied with electrical current sufficient to produce saturation.

Abstract: A method and apparatus are provided for effecting the inspection of a ferromagnetic element, or piping, and particularly piping that is already installed. The invention incorporates a device for indicating wall thickness of a length of the ferromagnetic element, including means for producing a value of magnetic flux extending longitudinally through a portion of the element. A voltage generating device is disposed in surrounding relationship to the element and is movable axially relative to the length of the element containing the value of the magnetic flux. Means for indicating the voltage generated in the voltage generating means by the value of the magnetic flux also are provided. A saturation level of magnetic flux is induced by a multi-turn supplied with electrical current sufficient to produce saturation. The voltage induced in a central pickup coil is amplified, integrated and correlated to average thickness of the pipe.

Abstract: A method and apparatus for determining the extent of defects in ferromagnetic tubular elements comprising a continuous string for use in an oil or gas well is disclosed. The tubing trip tool measures tubing average wall thickness, local defects, such as corrosion pitting, and axial defects, such as sucker rod wear during removal of the tubing from the well. Tubing velocity is also measured, and couplings between tubing sections are detected and counted, in order to specify the axial location of defects on each tube, and also provide a profile of the condition of the overall string. A saturating magnetic field and a fluctuating magnetic field are applied to the tubing and the magnitude of the induced fields and the changes are measured to quantify defects in the tubing.