METHOD AND SYSTEM FOR INSPECTION OF JOINTS IN COMPOSITE PIPES AND OF COMPOSITE REPAIRS IN METALLIC PIPELINES

Abstract

The present invention is related to techniques for the inspection of joints and repairs in pipelines. In this scenario, the present invention provides a method for the inspection of joints in composite pipes and of composite repairs in metal pipelines, comprising the steps of (i) emitting a series of acoustic wave pulses, at different frequencies, from a collar of acoustic transducers (4) positioned at a predetermined distance from the joint (5) or repair (1) to be inspected, (ii) recording, during a time interval subsequent to the emission, the echoes of the wave displacements up to the repair or joint in each of the transducers of the collar of acoustic transducers (4) in the form of A-Scan, and (iii) generating a planarized C-Scan image, by means of the CSM method, for each pulse emission frequency from the collar of acoustic transducers (4). The invention further provides a system for the inspection of joints in composite pipes and of composite repairs in metal pipelines associated with the method described above.

Claims

1. Method for the inspection of joints in composite pipes and of composite repairs in metal pipelines, characterized by comprising the steps of: emitting a series of acoustic wave pulses, at different frequencies, from a collar of acoustic transducers (4) positioned at a predetermined distance from the joint (5) or repair (1) to be inspected; recording, during a time interval subsequent to the emission, the echoes of the wave displacements up to the repair or joint in each of the transducers of the collar of acoustic transducers (4) in the form of an A-Scan; and generating a planarized C-Scan image, by means of the CSM method, for each pulse emission frequency from the collar of acoustic transducers (4).

2. Method, in accordance with claim 1, characterized by the step of generating a planarized C-Scan image, comprising processing the A-Scan data by means of back-propagation of the captured acoustic waves back to the positions from which they originated using the prior knowledge of the dispersion curves of the waveguide used.

3. Method, in accordance with claim 1 or 2, characterized by further comprising the step of circumferential evaluation of a particular defect revealed by the C-Scan using a predetermined threshold of comparison, in which: the number of channels reaching this threshold are computed; and the percentage value of the circumferential extent of the defect is computed based on the quantity of channels that reach the threshold.

4. Method, in accordance with any of claims 1 to 3, characterized by further comprising the step of longitudinal evaluation of a particular defect, in which: all of the A-Scans at the different pulse frequencies are added; the sum obtained in the previous step is transformed into the frequency domain where the distance between local minima of this curve corresponds inversely to the longitudinal extent between reflections; and the minimum longitudinal size of the defect is calculated based on the width of the frequency range used in the emission.

5. System for inspection of joints in composite pipes and of composite repairs in metal pipelines, characterized by comprising: a collar of acoustic transducers (4) positioned at a predetermined distance from the joint (5) or repair (1) to be inspected, adapted to emit a series of acoustic wave pulses at different frequencies; means of recording, during a time interval subsequent to the emission, the wave displacements in each of the transducers of the collar of acoustic transducers (4) in the form of A-Scan; and means of generating a planarized C-Scan image, by means of the CSM method, for each pulse emission frequency from the collar of acoustic transducers (4).

Description

BRIEF DESCRIPTION OF FIGURES

[0017] The detailed description presented below makes reference to the attached figures and their respective reference numbers.

[0018] FIG. 1 illustrates a schematic view of the system of the present invention applied to a polymeric or composite repair in a metal pipeline.

[0019] FIG. 2 illustrates a schematic view of the system of the present invention applied to a joint in a polymeric or composite pipeline.

[0020] FIG. 3 illustrates a graph of intensity versus time resulting from collection of the echoes of the mechanical waves by means of the system of the present invention, known as A-Scan.

[0021] FIG. 4 illustrates a graph of phase velocity versus frequency showing the dispersion curves for a polymeric pipe joint reinforced with fiberglass.

[0022] FIG. 5 illustrates a C-Scan type result of angular position versus distance.

[0023] FIG. 6 illustrates the steps of evaluation of the circumferential extent of a defect in accordance with the method of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0024] Preliminarily, it is emphasized that the description that follows will start from a preferred embodiment of the invention. As will be evident to any person skilled in the art, however, the invention is not limited to this particular embodiment.

[0025] FIG. 1 illustrates a schematic view of the system of the present invention applied to a polymeric or composite repair 1 in a metal pipeline 2. FIG. 2 in turn illustrates a schematic view of the system of the present invention applied to a threaded or bonded joint 5 in a polymeric or composite pipeline 6.

[0026] The system for inspection of joints in composite pipes and of composite repairs in metal pipelines, in accordance with a preferred embodiment of the present invention, will comprise a collar of acoustic transducers 4 positioned at a predetermined distance from the joint 5 or repair 1 to be inspected. Preferably, the transducers used in the collar of acoustic transducers 4 are piezoelectric transducers.

[0027] Preferably, the predetermined distance is up to 10 meters. More preferably, the predetermined distance is from 1 to 5 meters.

[0028] The collar of acoustic transducers 4 is adapted to emit a series of acoustic wave pulses at different frequencies. The pulses are preferably emitted in a controlled manner, followed by time intervals in which recordings are made of the echoes of the wave displacements up to the repair or joint in each of the transducers. Thus, the recordings are taken during a time interval subsequent to the emission, being stored in the form of A-Scan (FIG. 3).

[0029] Preferably, the series of pulse emissions should be realized with different emission frequencies to attain a specific band of frequencies. Preferably, the frequency band attained ranges from 10 kHz to 70 kHz.

[0030] The measurements of all the transducer elements of the collar are collected and stored in the form of A-Scans for the application of the methods of localization and evaluation of the defect.

[0031] The data in the form of A-Scan are then processed in order to back-propagate the captured waves back to the positions from which they originated using prior knowledge of the dispersion curves of the waveguide used. FIG. 4, for example, illustrates a graph of phase velocity versus frequency showing the dispersion curves for a polymeric pipe joint reinforced with fiberglass.

[0032] Preferably, the method utilized for processing the A-Scan data is the Common Source Method (CSM), widely used in the prior art for the processing of data in non-destructive tests. The application of the CSM results in a C-Scan which is a planarized image of the sound sources of the pipeline. FIG. 5 illustrates an example of a C-Scan that includes angular position versus distance axes.

[0033] Preferably, a planarized C-Scan image is generated for each pulse emission frequency from the collar of acoustic transducers 4.

[0034] The analysis of the generated C-Scan images permits the identification of points of interest in the area inspected. After a possible defect is localized using the C-Scan image, the longitudinal and circumferential positions of the defect on the surface of the pipeline are used to cut part of the A-Scan data in which two methods of evaluating the size of the defect are applied.

[0035] For the evaluation of the circumferential extent of a possible defect, a comparison threshold is used and the number of channels reaching this threshold is computed, and then the percentage value of the circumferential extent of the defect is computed as shown in FIG. 6.

[0036] To assess the longitudinal extent of the defect, it is necessary to use all of the A-Scans at the different pulse frequencies, added and transformed into the frequency domain where the distance between local minima of this curve corresponds inversely to the longitudinal extent between reflections, and therefore of the defect. The width of the frequency range utilized in the emission is linked to the minimum longitudinal size of the defect that will be able to be observed by the method.

[0037] The present invention further provides a system for inspection of joints in composite pipes and of composite repairs in metal pipelines associated with the above-described method. The system will comprise:

[0038] (i) a collar of acoustic transducers 4 positioned at a predetermined distance from the joint 5 or repair 1 to be inspected, adapted to emit a series of acoustic wave pulses at different frequencies;

[0039] (ii) means of recording, during a time interval subsequent to the emission, the wave displacements in each of the transducers of the collar of acoustic transducers 4 in the form of an A-Scan;

[0040] (iii) means of generating a planarized C-Scan image, by means of the CSM method, for each pulse emission frequency from the collar of acoustic transducers 4.

[0041] Thus, the present invention provides a fairly simple and practical method and system of non-destructive testing, which can be applied to joints in composite pipes as well as in composite repairs in metal pipelines.

[0042] Numerous variations covered in the scope of protection of the present application are permitted. Thus, it is emphasized that the present invention is not limited to the specific configurations/embodiments described above.