Abstract: Fluid transmission pipelines and similar structures which are cathodically protected from electrolytic corrosion and are disposed in urban areas under pavements and other structures which prevent access to the soil for verifying pipe-to-soil potentials are subjected to pipe-to-soil potential measurements using a reference electrode disposed in a container which has a permeable bottom and which is capable of saturating a pavement layer with a brine electrolyte to provide electrical conductivity between the reference electrode and the soil. Validation of electrical conductivity is made by a second reference electrode of a dissimilar metal which is also disposed in a container having a permeable bottom and an electrolyte which permeates the pavement layer and establishes electrical conductivity between the soil and the second reference electrode. Potential measurements between the first and second electrodes validate ion transport between the soil and the first reference electrode.

Abstract: There is provided a transient electromagnetic method and apparatus for inspecting objects. The apparatus includes a sensing portion, which has a transmitting antenna and at least one receiving antenna thereon. The sensing portion is located adjacent to the object which is to be inspected such that the antennas are adjacent to the object. There is also a magnet located adjacent to the sensing portion. The magnet has poles located adjacent to the object, so as to provide a steady-state magnetic field to the object. By applying a steady-state magnetic field to the object during inspection, increased inspection speeds and improved spatial resolutions can be achieved. In addition, casing can be inspected from inside of tubing.

Abstract: Fluid transmission pipelines and similar structures which are cathodically protected from electrolytic corrosion and are disposed in urban areas under pavements and other structures which prevent access to the soil for verifying pipe-to-soil potentials are subjected to pipe-to-soil potential measurements using a reference electrode disposed in a container which has a permeable bottom and which is capable of saturating a pavement layer with a brine electrolyte to provide electrical conductivity between the reference electrode and the soil. Validation of electrical conductivity is made by a second reference electrode of a dissimilar metal which is also disposed in a container having a permeable bottom and an electrolyte which permeates the pavement layer and establishes electrical conductivity between the soil and the second reference electrode. Potential measurements between the first and second electrodes validate ion transport between the soil and the first reference electrode.

Abstract: There is provided a transient electromagnetic method and apparatus for inspecting objects. The apparatus includes a sensing portion, which has a transmitting antenna and at least one receiving antenna thereon. The sensing portion is located adjacent to the object which is to be inspected such that the antennas are adjacent to the object. There is also a magnet located adjacent to the sensing portion. The magnet has poles located adjacent to the object, so as to provide a steady-state magnetic field to the object. By inducing eddy currents into the object, families of cracks, such as caused by environmental conditions, can be detected. In addition, magnetic flux leakage methods can be used in combination with the transient electromagnetic method to further assisting detecting crack families in pipeline inspection applications.

Abstract: There is provided a transient electromagnetic method and apparatus for inspecting objects using moving sensors. The apparatus includes a sensing portion, which has a transmitting antenna and at least one receiving antenna thereon. The sensing portion is located adjacent to the object which is to be inspected such that the antennas are adjacent to the object. The sensing portion is moved along the object at the same time the transmitting antenna is inducing current in the wall and the receiving antenna is producing a received signal of the induced current diffusion in the wall. Because the antennas are moving during data acquisition, the speed of inspection is increased. The data is then interpreted to determine the thickness of the object.

Abstract: A weld detection system for a pipeline survey pig includes a plurality of weld sensor units mounted spaced apart circumferentially on fore and aft pig support members and arranged in close proximity to the pipe wall. The sensor units comprise permanent magnet members for generating a magnetic flux field around a wire coil which is modified upon passing a girth weld or other magnetic anomaly in the pipe to produce a voltage signal which is conditioned by an amplifier and filter circuit to a signal suitable for input to a digital activation circuit. The digital activation circuit receives conditioned signals from opposed pairs of sensor units on the support members to distinguish transverse girth welds from spiral or longitudinal welds. The digital activation circuit includes circuit elements for timing the sensor output signals of the fore and aft detector arrays for measuring the velocity of the survey pig through the pipe.

Abstract: A traveling seal system for blocking a predetermined section of fluid transmission pipeline for repair or modification or for pressure testing the pipeline includes two seal devices which are interconnected by a flexible cable and are supported for traversal through a pipeline by spaced apart resilient support members supporting respective body members. Each of the seal devices includes radially extensible brake pads which are actuated by annular pistons slidable on the body of the seal devices, respectively, and are disposed in annular pressure chambers formed by the body. Each of the seal devices includes an onboard hydraulic pump for actuating the brake pads between extended and retracted positions and at least one of the seal devices includes an onboard pump for pumping pressure fluid into the space between the seal devices.

Abstract: A transient electromagnetic method for detecting irregularities on container walls by measuring wall thickness. The method utilizes a transmitting antenna and separate receiving antennas so as to form a loop-loop configuration. The transmitting antenna induces current into the container wall and the receiving antennas detect the induced current and produce received signals. The distance between the antennas and the container wall can vary, particularly where insulation is interposed therebetween. The variations in antenna distance affects the received signals. The affects are corrected by determining the maximum of the respective received signal and determining the arrival time of the maximum. The maximum and the arrival time are used to determine the thickness of the wall.

Abstract: There is disclosed a method for detecting corrosion on the walls of conductive containers wherein a transmitting antenna induces a current into a portion of the container wall and the decay of the induced current is detected by a receiving antenna, with a record of the decay of the induced current being created. The record is interpreted to determine the thickness of the container wall portion and the presence or absence of corrosion is inferred. The effects of variations in distance between the transmitting antenna and the receiving antenna and the pipe wall at one location on the pipe and between the transmitting antenna and the receiving antenna and the pipe wall at another location on the record of the decay are corrected for by examining the rate of decay of the induced current.

Abstract: A pipeline survey pig including an onboard inertial reference unit and signal processing units for receiving acceleration and angular velocity signals generated by the inertial reference unit, calculating resultant values of angular velocity and accelerations and averaging the calculated values to provide recordable signals related to the position of the pig and changes in curvature of the pipe. The pig is supported by a plurality of resilient cup shape support members which have a stiffness characteristic whereby the natural frequency of vibration which may cause lateral excursions of the pig is less than the signal generating rate yet greater than the frequency of the signal to be measured. The center of stiffness and the center of gravity of the pig are disposed along the central axis of the pig and the pipeline section being measured and are preferably coincident with each other.

Abstract: A pipeline survey pig including an onboard inertial reference unit and signal processing units for receiving acceleration and angular velocity signals generated by the inertial reference unit, calculating resultant values of angular velocity and accelerations and averaging the calculated values to provide recordable signals related to the position of the pig and changes in curvature of the pipe. The pig is supported by a plurality of resilient cup shaped support members which have a stiffness characteristic whereby the natural frequency of vibration which may cause lateral excursions of the pig is less than the signal generating rate yet greater than the frequency of the signal to be measured. The center of stiffness and the center of gravity of the pig are disposed along the central axis of the pig and the pipeline section being measured and are preferably coincident with each other.

Abstract: A change in curvature or displacement of a section of submarine or subterranean fluid transmission pipeline is measured by traversing the pipeline with a pig having an onboard instrument package, including accelerometers and a longitudinal position measuring device comprising a magnetometer for counting the girth welds or other known magnetic anomalies along the section of pipeline to be measured. The accelerometers are mounted at the central longitudinal axis of the pig which is substantially coincident with the central longitudinal axis of the section of pipeline being measured so that the roll attitude of the pig does not influence the signals generated by the accelerometers. This arrangement precludes the requirement of mounting the accelerometers on a gyroscopic stabilized platform since the absolute position of the pig in space is not required, but primarily the change in curvature or displacement of the pipeline from a predetermined course is what is desired to be known.