Measuring and testing – Inspecting
Reexamination Certificate
1998-10-16
2001-03-06
Raevis, Robert (Department: 2856)
Measuring and testing
Inspecting
Reexamination Certificate
active
06196075
ABSTRACT:
This application claims Paris Convention Priority of German Patent application number 197 46 511.0 filed Oct. 22 1997, the complete disclosure of which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
The invention concerns a device for the inspection of pipes having sensors disposed about an outer periphery.
In order to inspect pipelines, in particular those under water or pipelines traveling below the earth, conventional so-called inspection pigs are utilized having inspection devices with inspection elements or sensors disposed about an outer girth by means of which the condition of the walls of the pipes can be inspected. The sensors can be effected in differing manners; piezoelectric sensors, Electro-acoustic sensors electromagnetic sensors such as Hall sensors, stray field sensors and eddy current sensors are all known in the art. Differing wall conditions, e.g. due to corrosion etc. provide differing signals to be further processed in an electronics unit.
Particularly for the case of conduits traveling under water, it is extremely expensive to provide an input location and extremely difficult to introduce an inspection pig into such a conduit. For example, difficult and expensive input lock mechanisms having expensive valves must be provided for. For introduction, a diver must submerge to substantial depths to introduce such a pig into a pipeline so that the pig can travel through and inspect same. On the other hand, this type of pipeline can have a relatively large diameter, on the order of the magnitude of e.g. 40 inches (corresponding to 1 m), and therefore cannot be passed from the ground to the upper surface of the water, since its weight is prohibitive.
It is the underlying purpose of the invention to create a device for the inspection of pipelines which avoids the above mentioned disadvantages and facilitates, in particular, a simple introduction into the pipeline.
SUMMARY OF THE INVENTION
This purpose is solved in accordance with the invention using a device for the inspection of pipes having sensors disposed about an outer girth thereof which is characterized by radially expandable inspection units.
The solution in accordance with the invention allows a pig to be passed through an introductory pipe having a smaller diameter, e.g. a diameter of 16 or 28 inches (corresponding to approximately 40 and 70 cm, respectively) and introduced to the main conduit having the above mentioned diameter, whereas the pig has a smaller diameter than the introductory conduit and can expand to the larger diameter of the main conduit passing the medium while nevertheless permitting a reliable inspection of the pipe conduit by means of the sensors disposed around its outer girth (in the respective expanded position).
A most preferred embodiment provides for a front and a back inspection unit having sensors disposed about their girths in a displaced fashion and which can be axially moveable relative to each other. The expansion of sensors located on arms of such a pig causes an increase in their angular separation within an inspection unit. On the other hand, one must inspect the pipe conduit about its entire periphery. This is fundamentally possible in that sensors, when appropriately axially displaced, are disposed in such a fashion as to cover the entire periphery of the pipe. Since however the signals from the individual sensors have to be correlated and in particular since, when passing though curves in the pipe conduit, the relative angular positions of the sensors, possibly provided on two differing inspection units, does not remain defined, it is therefore advantageous to completely cover the entire girth of the pipe conduit with sensors at one axial position. This is accomplished in the above mentioned preferred embodiment in that the inspection units are capable of displacement towards each other in such a fashion that the mutually angular-displaced sensors of the two inspection units occupy the same axial position. This guarantees that the entire girth of the pipe is covered by sensors and appropriately inspected at a common axial position when the device for inspection of pipe conduits is expanded.
In order to avoid difficult and expensive active displacement mechanisms for the inspection units which would require their own drive and power supply (the providing of sufficient electrical power to a pig is difficult since this must be supplied in the form of batteries or rechargeable batteries over substantial lengths and over long periods of time), the invention provides, in a most preferred improvement, that the rear inspection unit be moveable towards the front inspection unit under the action of the flow pressure of the fluid flowing in the pipeline, wherein, in particular, the back inspection unit can be moved towards the front inspection unit by means of a pull unit. The pull unit thereby has a collar which seats under the action of fluid pressure on the inner wall of the pipe conduit and is also pushed in a forward direction under the pressure of the flowing fluid such that it moves together with the rear inspection unit in the direction of motion of the inspection pig and in the direction of motion of the device for inspection of the pipeline conduits in a manner more rapid than the front inspection unit (relative to an external stationary point) to thereby more towards the front inspection unit. Since the extensive additional elements of an inspection pig such as electronic units, power supply units etc. are connected to the rear inspection unit and the pull unit, the front inspection unit moves relative to this residual portion of the inspection pig.
Further preferred embodiments of the invention provide that the inspection units are fixed relative to each other in certain angular positions, wherein, in particular, the sensors of the inspection units are disposed in angular displaced positions in such a manner that a sensor of the front inspection unit has an angular position midway between two neighboring sensors of the rear inspection unit with sensors of an inspection unit being aligned with each other.
A preferred embodiment provides that the inspection units can radially expand under the action of a spring force. In this manner, one guarantees that the sensors of the inspection units are pushed closely against the inner wall of the pipe conduit, wherein a predetermined defined separation can be effected by guide rollers mounted to a sensor support along with the sensors to guarantee that the sensors are located at a small defined radial separation from the inner wall of the pipe conduit while not coming in contact therewith, to prevent wear. A further improved embodiment can provide that the sensors be disposed on parallelogram rods. In this manner a stable configuration of the expandable inspection unit system is created, wherein one guarantees that, independent of the expansion position, the sensors always remain constantly parallel to the axis.
An additional preferred configuration is characterized by a releasable blocking mechanism to axially fix one of the inspection units, in particular the front inspection unit, to a guide element (guide rod), wherein, in particular, a release mechanism for releasing the blocking mechanism is provided when the corresponding inspection unit has reached its expansion position. This guarantees that, in the introductory position of the inspection unit, the front inspection unit is blocked on a guide rod at an axial separation with respect to the rear inspection unit and can not move relative thereto to prevent damage. One simultaneously guarantees that, when a predetermined radially expansion position is reached, the blocking mechanism is released so that the above mentioned relative motion between the two inspection units can transpire and the inspection units can move towards each other in an axial direction so that their sensors can occupy the desired common axial position (with angular displacements).
Further advantages and features of the invention can be extracted from the claims and the following des
Comello Corry
Laursen Poul
Maki Jukka
Pipetronix GmbH
Raevis Robert
Vincent Paul
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