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.

Description

FIELD OF INVENTION

The present invention is related to pipeline inspection techniques. More specifically, the present invention is related to techniques for the inspection of joints and repairs in pipelines.

BACKGROUND OF THE INVENTION

Composite materials are being increasingly used in various industrial sectors. The aerospace sector is the largest user of this type of material. However, industries of the petroleum, gas, and energy sectors are following this trend, primarily because of the high strength/weight ratio, immunity to corrosion, and possibility for “cold” application of these materials. In the petroleum and gas industry, the possibility for cold application of joints and repairs is very attractive because it eliminates the need to isolate the environment and leave it free of combustion and explosion risks.

Two classes of applications for composite materials are being established in the petroleum, gas, and energy industry: repairs with composite materials and structural materials produced entirely of composite materials. The first involves the application of a layer of composite material over a metal structural element, serving as a barrier to corrosion or as a structural reinforcement. The second class primarily involves pipes and pressure vessels consisting entirely of composite materials.

In the petroleum, gas, and energy industry, the history of failures with composite materials is predominantly related to assembly defects or problems during the application of coatings in the field. This is the typical case of repairs and protective coatings of composites and of connections between pipes of composite materials.

In both cases, the conditions of application are normally not favorable, resulting in a higher probability of incidence of defects such as: adhesion failures (at the metal-composite and composite-composite interfaces); delaminations (adhesion failures between layers of the composite); inclusions (presence of bubbles and foreign bodies between layers of the composite); and non-homogeneity in the distribution of fibers in the composite. There can also be structural defects stemming from the manufacturing process of the components.

Defects in protective coatings and repairs can compromise the efficacy of the protection or structural reinforcement. If not detected and corrected, defects in joints and connections of composite pipe structures can evolve and lead to operational failures, entailing the risk of product leakage.

The use of composite repairs in metal pipelines has increased in the field; however, the lack of an inspection tool makes its use highly restricted. Thus, in the current state of use of these materials, it is imperative to inspect the coatings and repairs applied in the field as well as connections and joints in composite structures.

The current prior art is replete with the most varied techniques for pipeline inspection, as can be observed in the examples below.

The document EP1523393B1 discloses a method for the inspection of welds in pipelines via the arrangement of a series of electromagnetic acoustic transducers (EMAT) arranged circumferentially in relation to the internal or external wall of the welded end of the pipeline. By inducing the EMAT arrangement to sequentially or simultaneously transmit acoustic shear wave signals of different modes and at different angles toward the weld, it is possible to detect shear waves.

However, the technique of document EP1523393B1 does not apply to joints in composite/polymeric pipelines, nor to polymeric/composite repairs in metal pipelines.

The documents RU2380699C1, RU2278378C1, and U.S. Pat. No. 7,424,910B2 disclose methods for detecting defects between polymeric coatings and metal pipelines. However, these techniques do not apply to joints of pipelines of composite or polymeric materials, for example.

Thus, there is a need in the prior art for an efficient method that encompasses the inspection of joints in composite/polymeric pipelines and polymeric/composite repairs in metal pipelines, both of which are currently widely used in the petroleum and gas industry.

As will be explained in greater detail below, the present invention aims to solve the aforementioned problem of the prior art in a practical and efficient way.

SUMMARY OF THE INVENTION

The present invention has the main goal of providing a method and system of non-destructive inspection that can be applied to joints in composite pipes and in composite repairs in metal pipelines.

In order to achieve the objective described above, the present invention provides a method for inspection of joints in composite pipes and 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 positioned at a predetermined distance from the joint or repair 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 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.

The present invention also provides a system for inspection of joints in composite pipes and of composite repairs comprising (i) a collar of acoustic transducers positioned at a predetermined distance from the joint or repair to be inspected, adapted to emit a series of acoustic wave pulses at different frequencies, (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 in the form of A-scan, and (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.

BRIEF DESCRIPTION OF FIGURES

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

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

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

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.

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

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

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

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.

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.

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.

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

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).

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.

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.

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.

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.

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

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.

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.

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.

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:

(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;

(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;

(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.

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.

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.

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; andgenerating 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; andthe 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; andthe 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; andmeans 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).