EP3529607A1

EP3529607A1 - Method for automatically inspecting a weld bead deposited in a chamfer formed between two metal pieces to be assembled

Info

Publication number: EP3529607A1
Application number: EP17793989.9A
Authority: EP
Inventors: Nicolas FEUILLY; Marco Aurelio OCCHILUPO; Eric Kerdiles
Original assignee: Saipem SA
Current assignee: Saipem SA
Priority date: 2016-10-19
Filing date: 2017-10-10
Publication date: 2019-08-28
Also published as: CN109844517A; MX2019004486A; CA3039923A1; US20190242853A1; FR3057668A1; MA45514A1; AU2017345361B2; WO2018073511A1; MY195949A; FR3057668B1; US11585788B2; BR112019007630A2; PH12019500729A1; MA45514B1; ZA201902566B; AU2017345361A1

Abstract

The invention relates to a method for automatically inspecting a weld bead (24) deposited, in several passes, in a chamfer (18) formed between two parts (20, 22) to be assembled, comprising the following steps: positioning at least one electromagnetic acoustic sensor that emits ultrasound waves (2) on one side of the chamfer and at least one electromagnetic acoustic sensor that receives ultrasound signals (2) on an opposite side of the chamfer, the sensor that emits ultrasound waves being configured to emit Rayleigh surface waves; during the deposit of one pass, automatically moving the sensors by following the movement of the welding electrodes along the chamfer; activating the sensors during their movement to allow the emitting sensor to generate and emit Rayleigh waves in the direction of the pass of the weld bead being deposited, the receiving sensor receiving the ultrasound signals transmitted and/or reflected in said pass; and repeating the operation for the entire pass of the weld bead.

Description

Title of the invention

A method of automatically inspecting a weld bead deposited in a chamfer formed between two metal parts to be assembled Background of the Invention

The present invention relates to the general field of non-destructive testing of a weld bead deposited in a chamfer formed between two metal parts to be assembled.

A non-limiting field of application of the invention is that of the inspection of an annular weld bead deposited between two tubular conduits placed end to end, in particular between two tubular elements of an underwater pipe intended for transport. hydrocarbons.

The non-destructive inspection inspection techniques are used in the petroleum industry to reveal the presence of defects in a weld bead deposited in particular by arc welding between two tubular pipe elements, such as gaps. melting, cracking, inclusions or porosities, and possibly quantifying them.

One of the techniques currently used in the petroleum industry to inspect a weld bead deposited between two tubular pipe elements during the precast phase of the pipeline or when it is laid in S or J is X-ray.

This technique is particularly used to inspect end-to-end welds of tubes internally plated with a corrosion resistant alloy layer (eg Inconel ^® ). Typically, this alloy layer has a thickness of between 2.5 mm and 5 mm and internally lining the inner surface of the carbon steel tube in order to improve its mechanical and chemical properties.

In order to coat the inner surface of carbon steel tubes with a layer of anticorrosive alloy, one of the techniques, mainly used when the pipe is subjected to high fatigue stresses, is to heat-roll the anticorrosive alloy layer. on a carbon steel sheet to obtain a metallurgical bond between the two materials. Another technique is to reload the inner surface of a carbon steel tube with the anticorrosive alloy by successive deposits. However, the construction requirements of the pipe are becoming more and more stringent, particularly with regard to the inspection of end-to-end welds of internally plated tubes. In particular, these requirements require, in addition to a final radiography of the weld beads, an intermediate radiography to ensure the absence of defects in the weld at the location of the plating. Productivity is then affected because the inspection must be done in two stages. This results in an increased cycle time of 15 to 20 minutes per weld due solely to the requirement for additional radiography.

Another technique used to inspect end-to-end welds of tubes internally plated with a corrosion resistant alloy layer is automated ultrasonic testing (also referred to as AUT for Automated Ultrasonic Testing). This technique uses ultrasonic phased array probes ("Phased Array" in English), that is to say probes comprising a matrix of ultrasonic sensors mono-elements used for inspection. These ultrasonic sensors can both emit and receive ultrasound. These are generally piezoelectric sensors converting an ultrasonic wave into an electric current and vice versa.

However, this technique has the disadvantage of being able to be implemented only after the welding completed and cooled to a temperature below 90 ° C. Indeed, the piezoelectric effect of these sensors disappears above 200 ° C. In addition, since water is usually used as an ultrasonic coupling between the sensors and the surface of the part to be inspected, the surface temperature of this part can hardly exceed 100 ° C. Finally, the hooves associated with these sensors and within which the ultrasonic waves are generated, see their mechanical characteristics evolve with temperature. This causes variations in wave speeds, which degrade the performance of ultrasonic inspection.

US 4,588,873 discloses the disclosure of a real-time ultrasonic inspection method of a weld bead W single-pass deposited in a chamfer formed by two pieces PI, PII. To this end, it plans to use two acoustic transducers for transmitting and receiving ultrasonic waves of volume PRA, PRB positioned on the one hand and on the other hand, the chamfer. The ultrasonic waves of volume (transverse or longitudinal) generated and received by these same two sensors are sent in real time to a control device that adjusts certain welding parameters to correct the appearance of defects in the welding step.

The inspection method as described in US 4,588,873, however, has many disadvantages. Indeed, the propagation of ultrasound waves in the part to be inspected requires the use of a coupling fluid between the sensor and the surface of the part. This couplant is in the form of gel or water (liquid). However, this coupling fluid can flow into the chamfer and cause the appearance of defects (i.e. porosity, cracking, etc. etc.) in the final weld bead. Due to the positioning of the sensors, this coupling fluid can negatively impact the microstructure of the welding bead (deterioration of the mechanical properties such as hardness, elasticity, etc.) by a too rapid cooling (quenching) thereof. during the real-time inspection. In addition, the use of conventional ultrasonic probes limits inspection to temperatures above 100 ° C. Finally, conventional ultrasonic sensors such as those presented in US 4,588,873 generate ultrasonic waves of volume (compression and / or shear) limited to operating in "pulse-echo" mode during inspection. With this inspection methodology, the interpretation of the ultrasonic signals is disturbed by the partially filled chamfer geometry. In addition, real-time inspection requires changing the penetration angle of volume ultrasonic waves, in order to target and inspect in real time each successive weld bead.

Yet another technique used to inspect end-to-end welds is to replace piezoelectric sensors with electro-acoustic sensors (this technology is known as EMAT for "Electro-Magneto-Acoustic Transducer"). The general principle of ultrasonic emission by EMAT is as follows: a coil, traversed by an alternating electric current and placed close to the weld bead to be controlled, induces surface-distributed currents, called "eddy currents", in an area where a permanent magnetic field has been established. Magnetic field interaction Permanent eddy currents give rise to Lorentz forces and magnetostriction on the surface of the metal which themselves result in a displacement of particles of the same metal, thus generating ultrasonic waves propagating directly in the material being inspected. These ultrasonic waves thus make it possible to highlight the existence of defects in the weld bead and to characterize these defects as a function of the alterations that the ultrasonic waves have undergone during their propagation.

Document WO 2004/007138 thus discloses the application of the EMAT principle for the inspection of an annular weld bead deposited between two tubular elements. For this purpose, this document describes an inspection apparatus which is mounted around the weld bead to be inspected and which remains fixed with respect thereto during the actual inspection operation, this apparatus comprising two electromagnetic sensors -acoustics positioned above and below the weld seam at a distance of 2mm from it.

However, the EMAT inspection method described in publication WO 2004/007138 has numerous drawbacks. Indeed, the inspection apparatus being fixed relative to the weld bead, the inspection can be performed once the weld bead fully deposited in the chamfer between the two tubular elements. The inspection method described in this document uses cross-wave emission to inspect the weld seam. However, the use of this type of wave does not allow to inspect the complete volume of a multi-pass weld. In addition, depending on the frequency of the transverse waves used or their angle of emission, the detection of certain defects present in the weld bead such as melting defects or porosities, may not be detected, because of their low dimension or their spatial orientation.

Object and summary of the invention

The present invention therefore has the main purpose of providing a method of inspection of a weld bead which does not have the aforementioned drawbacks.

According to the invention, this object is achieved thanks to a method of automatic inspection of a weld bead deposited in several passes in a chamfer formed between two metal parts to be assembled, the different passes of the weld bead being deposited by means of welding electrodes moving along the chamfer, the method comprising the following steps:

positioning at least one electro-acoustic ultrasonic wave emission sensor on one side of the chamfer and at least one electro-acoustic ultrasonic signal receiving sensor on an opposite side of the chamfer, the electro-acoustic emission sensor ultrasonic waves being configured to emit Rayleigh surface waves;

during the deposition of a weld bead pass by the welding electrodes, automatically moving the electro-acoustic sensors following the movement of the welding electrodes along the chamfer;

activate the electro-acoustic sensors during their displacement to allow the electro-acoustic emission sensor to generate and emit Rayleigh surface waves in the direction of the pass of the weld bead being deposited, the electro-acoustic sensor of reception receiving ultrasonic signals transmitted and / or reflected in said pass; and

repeat the operation for the entire weld bead pass.

The inspection method according to the invention is remarkable in particular because it allows an inspection of the different passes of the weld bead during their deposit in the chamfer. Indeed, electromagnetic-acoustic sensors (EMAT) are movable relative to the metal parts to be assembled (which remain fixed) and move following the movement of the welding electrodes. Thus, it is possible to detect in real time the presence of possible defects in the different passes of the weld bead during their deposit.

The inspection method according to the invention is also remarkable in that the electromagnetic-acoustic sensors generate ultrasonic waves directly in the part to be inspected and do not require the use of a shoe or that of a coupling fluid which allows ultrasonic inspection of the workpiece at surface temperatures of up to at least 310 ° C. The inspection method according to the invention is also remarkable in that the electro-acoustic ultrasonic wave emission sensors are configured to emit Rayleigh surface waves, that is to say surface waves combining both longitudinal and transverse modes to create an elliptical orbit movement which, as it propagates, follows the surface of the material to be inspected. The interest of this type of wave, combined with a real-time inspection during the deposition of each pass of the weld bead, is that it makes it possible to highlight all the possible welding defects present in the entire volume. of each pass, and thus ultimately throughout the thickness of the weld bead consists of all successive passes. The set of data that make up an ultrasonic signal such as the travel time of the ultrasonic wave, but also the energies transmitted and reflected by the wave and the resulting waves and their frequencies is used to detect and characterize the indications potentially present in the weld inspected.

The inspection method according to the invention has many advantages over the X-ray inspection technique. Indeed, this method makes it possible to overcome the problems of radiation protection and to eliminate the security and environmental risks. Compared with conventional X-ray or ultrasonic inspection techniques, the inspection time of a weld is also considerably reduced, which is a significant advantage in the oil field for assembling the tubular elements of the transport pipes. hydrocarbons. In addition, the method can be implemented at high temperature, which avoids having to wait for the cooling of the weld seam to inspect it. In addition, the inspection is carried out in real time during the deposition of the different passes of the weld seam, which considerably reduces the cycle time and improves the productivity of the welding and inspection steps. Furthermore, the method according to the invention is particularly well suited to the control of annular welding beads deposited between two plated tubes.

Preferably, the method further comprises, on reception of ultrasonic signals characteristic of a defect in the current pass deposition by the electromagnetic-acoustic sensor, the modification during the pass of certain welding parameters in order to correct said defect.

In this case, the modification during the pass of certain welding parameters can be performed by an operator.

Alternatively, the modification during the pass of certain welding parameters is advantageously performed automatically according to an automatic learning mode classes and examples of welding defects.

This characteristic is thus remarkable in that it makes it possible to adapt favorably and in real time the welding parameters (the speed of advance of the welding wire, the speed of advance of the welding torch or torches, their position, their oscillation, intensity and voltage required to create the welding arc, etc.) as a function of the received ultrasonic signals. A closed-loop control method for welding and inspection operations is envisaged which uses machine learning. From a self-refreshing data library consisting of imperfections observed in the past welds, the ultrasonic signals recorded by the inspection method according to the invention are processed so as to favorably adapt the welding parameters. to correct the presence of imperfection and to facilitate the decision-making of the operator in order to initiate any corrective action.

Also preferably, the Rayleigh surface waves generated by the electro-acoustic ultrasonic wave emission sensor are waves emitted at a frequency between 200 kHz and 4.5 MHz. Such a frequency corresponds to the emission of surface waves of the Rayleigh wave type.

More preferably, the process steps are repeated for each pass of the weld bead deposited in the chamfer. It is thus possible to detect the presence of possible defects throughout the thickness of the weld bead, not only at the level of the last pass.

More preferably, the electromagnetic-acoustic sensors are kept in permanent contact with a surface of one of the two parts to be assembled so as to avoid any loss of signal during the inspection. In an exemplary application, the parts to be assembled are tubular conduits placed end to end, the chamfer having an annular shape.

In this application example, the method may advantageously furthermore comprise, during the entire duration of the inspection, the acquisition of the angular position of the electro-acoustic sensors with respect to the axis of revolution of the chamfer so as to determine the circumferential location of any defect in the weld bead pass being deposited.

In this case, the acquisition of the angular position of the electro-acoustic sensors can be achieved by means of a rotary encoder coupled to a movable carriage carrying the electro-acoustic sensors.

The mobile carriage carrying the electro-acoustic sensors can thus be connected to a carriage carrying the welding electrodes to move therewith during the deposition of a weld bead pass. In addition, the mobile carriage carrying the electro-acoustic sensors can move in a circumferential direction about the axis of revolution of the chamfer along an annular guide strip positioned on one of the tubular conduits, in particular by the intermediate of an electric motor, while being able to be held stationary in any angular position.

The electro-acoustic sensors may comprise an electro-acoustic ultrasonic signal receiving sensor and an electro-acoustic ultrasonic wave emission sensor positioned on one side of the chamfer, and another electro-acoustic ultrasonic signal receiving sensor. positioned on the opposite side of the chamfer.

Alternatively, the electro-acoustic sensors may comprise an electromagnetic-acoustic sensor for receiving ultrasonic signals and an electro-acoustic transducer for emitting ultrasonic waves positioned on one side of the chamfer, and another electro-acoustic transducer for receiving ultrasound signals. ultrasonic signals and another electro-acoustic ultrasonic wave emitting sensor positioned on the opposite side of the chamfer. Brief description of the drawings

Other features and advantages of the present invention will emerge from the description given below, with reference to the accompanying drawings which illustrate an embodiment having no limiting character. In the figures:

FIGS. 1A and 1B show an example of an electromagnetic-acoustic sensor used for the implementation of the inspection method according to the invention, respectively in front view and side view;

FIGS. 2A to 2C illustrate the propagation of the surface waves implemented by the inspection method according to the invention during the deposition respectively, of the first pass, of an intermediate pass and of the last pass of a cord. welding in a V-shaped chamfer;

FIGS. 3A to 3D schematically illustrate different configurations of electromagnetic and acoustic sensors for implementing the inspection method according to the invention;

FIGS. 4 and 5 show schematically, respectively in top view and in side view, an exemplary implementation of the method according to the invention in the case of the inspection of an annular weld bead deposited between two tubular conduits placed end to end;

FIG. 6 schematically shows a top view of an alternative embodiment of the example of FIGS. 4 and 5; and

FIGS. 7 and 8 are curves showing a possible representation of the ultrasonic signal received by the EMAT sensors implemented by the inspection method according to the invention.

Detailed description of the invention

The invention applies to the inspection (or non-destructive testing) of any weld bead deposited in one or more passes in a chamfer (for example V or J) formed between two metal parts to be assembled. The inspection reveals the presence of defects in the weld bead, these defects may be including cracks, inclusions, porosities or lack of fusion.

One non-limiting field of application of the invention is that of the inspection of an annular weld bead deposited by electric arc welding in one or more passes in a chamfer formed between two tubular elements placed end to end to form an underwater pipe for the transport of hydrocarbons. By way of example, the tubular elements may be tubes that are internally plated with a corrosion-resistant alloy layer.

Of course, and more generally, the method according to the invention applies to the inspection of other types of weld bead deposited in one or more passes in a chamfer, and in particular to weld beads which are rectilinear.

The inspection method according to the invention provides for the use of electro-acoustic sensors for transmitting and receiving ultrasonic waves. These electromagnetic-acoustic sensors are called in the following description "EMAT sensors" (for "Electro-Magneto-Acoustic Transducer").

FIGS. 1A and 1B show an example of such an EMAT sensor 2 used for carrying out the inspection method according to the invention, respectively in front view and side view.

As shown in these figures, the EMAT sensor 2 is positioned inside a casing 4 of substantially parallelepiped shape. At its upper surface, this housing 4 is provided with a connector 6 intended to be connected to a power supply system and to a data acquisition and processing unit using automatic learning, itself connected to the possibly self-adaptive welding system (not shown in the figures). At its lower surface, the casing comprises wheels 8 intended to allow movement of the sensor on the surface of the parts to be assembled and to ensure permanent contact with this surface to avoid any loss of signal during inspection.

The EMAT sensor 2 itself consists of a flat coil 10 which is placed at the bottom surface of the housing 4 and which is held flat on the surface of the parts to be assembled by means of rollers 12. The EMAT sensor also comprises an electromagnetic coil 14 and a protective film 16.

The operation of such an EMAT sensor is as follows: the flat coil 10, traversed by an alternating electric current and placed close to the weld bead to be controlled, induces surface-distributed currents, called "eddy current", in an area where a permanent magnetic field through the electromagnetic coil 14. The permanent magnetic field-eddy currents interaction gives rise to Lorentz forces and magnetostriction on the surface of the metal which themselves result in a displacement of the particles, thus generating ultrasonic waves propagating in the metal. These ultrasonic waves thus make it possible to highlight the existence of defects in the weld bead and to characterize these defects as a function of the alterations that the ultrasonic waves have undergone during their propagation.

The EMAT sensor 2 can operate in transmission or reception of ultrasonic waves. In FIGS. 2A-2C, the EMAT sensors for emitting in the weld bead material to examine ultrasonic waves are illustrated by the reference 2-T, while the EMAT sensors for receiving the transmitted and / or reflected ultrasonic signals. by the material of the weld seam bear the reference 2-R.

According to the invention, the EMAT 2-T sensors are configured to emit surface ultrasonic waves of the Rayleigh surface wave type, that is to say surface waves combining both longitudinal and transverse modes to create a elliptical orbit movement which, when propagated, follows the surface of the material to be inspected.

The penetration depth in the material to be inspected by these Rayleigh waves is directly correlated to the pitch of the EMAT 2-T flat coil 10 and the frequency of the transmitted waves. Typically, a transmission frequency of the ultrasonic waves between 200 kHz and 4.5 MHz will be used.

From sensors EMAT 2-T, 2-R as described above, the inspection method according to the invention provides for positioning these sensors on either side of a chamfer formed between the two parts to be assembled, with at least one EMAT 2-T sensor placed on one side of the chamfer and at least one EMAT 2-R sensor placed on the other side (ie on the opposite side) of the chamfer.

An example of positioning of these sensors EMAT 2-T, 2-R on either side of a chamfer (V-shaped in the example) 18 formed between two parts to be assembled 20, 22 is shown schematically on the Figure 2A. Specifically, in this example, a single EMAT 2-T ultrasonic wave transmitter and a single EMAT 2-R sensor reception of ultrasonic signals are positioned on either side of the chamfer 18.

Once the EMAT 2-T, 2-R sensors are positioned on either side of a chamfer formed between the two parts to be assembled, the inspection method according to the invention provides, during the filing of a pass welding bead by the welding electrodes in the chamfer, to automatically move the EMAT sensors following the movement of the welding electrodes along the chamfer, while activating the EMAT sensors during their movement to allow the EMAT sensor to 2-T emission to generate and emit Rayleigh waves in the direction of the weld bead pass during deposition, the 2-R receiving EMAT sensor receiving ultrasonic signals transmitted and / or reflected in said pass. This operation is repeated for the entire weld bead pass, then for all the passes deposited in the chamfer.

According to this inspection method, FIG. 2A also represents the propagation of the ultrasonic waves 0 emitted by the EMAT 2-T sensor and received by the EMAT 2-R sensor in the case where the first pass P 1 of a weld bead is in the process of being filed in chamfer 18.

As shown in this FIG. 2A, when the ultrasonic wave O emitted by the EMAT 2-T sensor encounters the upper corner 18-Sl of the chamfer 18, a reflected surface wave propagates but the majority of the energy continues to follow the 18-F1 face of the chamfer until reaching the first pass Pl of the weld bead that it passes right through before going up along the other face 18-F2 of the chamfer to the opposite upper corner 18-Sl of the chamfer to reach the EMAT 2-R sensor.

The ultrasonic wave 0 'that arrives at the sensor EMAT 2-R receiving ultrasonic signals has a lower energy than the wave O emitted. When a fault is present in the first pass P1, this defect will generate a reflection and a dispersion of the ultrasonic wave O which passes through the first pass, so that the detection of this defect will be directly correlated to the amount of energy the ultrasonic signal received by the EMAT 2-R sensor. The characterization of the defect and its dimensioning will be correlated to the data set constituting the ultrasonic signal received: travel time of the ultrasonic wave, amount of energy received, frequency, etc.

FIG. 2B also shows the propagation of the ultrasonic waves 0 emitted and received by the EMAT 2-T, 2-R sensors in the case where an intermediate pass P-I of the weld bead is being deposited in the chamfer 18.

The propagation of the wave 0 emitted by the EMAT 2-T emitter of ultrasonic waves is similar to that described for the case of FIG. 2A: the energy of the wave 0 propagates essentially the along the upper part of the face 18-F1 of the chamfer 18 passes through the intermediate pass PI before going up along the upper part of the other face 18-F2 of the chamfer to finally reach the EMAT 2-R sensor. Here also, the detection of a possible fault in the intermediate pass P-I will be detected according to the amount of energy transmitted by the wave 0 'and received by the sensor EMAT 2-R. The characterization of the defect and its dimensioning will be correlated with all the data constituting the received ultrasonic signal: travel time of the ultrasonic wave, amount of energy received, frequency, etc.

FIG. 2C again represents the propagation of the ultrasonic waves O emitted and received by the EMAT 2-T, 2-R sensors in the case of the deposition of the last pass (or final pass) P-F of the weld bead.

The propagation of the wave O emitted by the ultrasonic wave emitting sensor EMAT 2-T is as follows: the energy of the wave O propagates essentially directly from an upper corner 18-S1 of the chamfer 18 to the opposite corner 18-S2 crossing right through the final pass PF weld seam. The detection of a possible fault in this final pass P-F will be detected as a function of the amount of energy transmitted by the wave O 'and received by the sensor EMAT 2-R. The characterization of the defect and its dimensioning will be correlated with all the data constituting the received ultrasonic signal: travel time of the ultrasonic wave, amount of energy received, frequency, etc.

It is readily understood from the foregoing that the inspection method according to the invention makes it possible to ensure control of the cord of solder for each pass of it. In particular, the inspection is not simply limited to the final pass PF but to all the passes deposited in the chamfer to form the weld seam. The invention thus makes it possible to detect and dimension with the same sharpness any possible defect present in all the successive passes of the weld bead, from the first pass P1 to the final pass PF.

Furthermore, the advantage of this inspection method is that the axial position of the EMAT 2-T, 2-R sensors does not need to be modified to inspect all the passes deposited to form the weld bead. .

As described above, the inspection method according to the invention requires positioning at least one EMAT 2-T ultrasonic wave emission sensor on one side of the chamfer and at least one EMAT 2-R signal receiving sensor. ultrasound on the opposite side of the chamfer.

Different configurations illustrated schematically in FIGS. 3A to 3D are thus conceivable for the implementation of the inspection method according to the invention.

Thus, the configuration of FIG. 3A provides for positioning an EMAT sensor for receiving 2-R ultrasonic signals and an EMAT emission sensor for ultrasonic waves 2-T on one side of the chamfer 18 formed between the two parts 20, 22 to be assembled, and another EMAT sensor for receiving 2-R ultrasonic signals on the opposite side of the chamfer (2-R / 2-T / 2-R configuration).

The configuration of Figure 3B is similar to that of Figure

3A by its number of ultrasonic wave reception and emission EMAT sensors (ie a 2-R receive EMAT sensor and a 2-T transmit EMAT sensor on one side of the bevel 18, and a single sensor 2-R receiving EMAT on the other side of the chamfer), with a reversal in the order of arrangement of the EMAT 2-T and 2-R sensors positioned on the same side of the chamfer (2-T / 2-R configuration / 2-R).

The configuration illustrated in FIG. 3C shows the positioning of an EMAT sensor for receiving 2-R ultrasonic signals and an EMAT emission sensor for ultrasonic waves 2-T on one side of the chamfer 18 formed between the two parts. , 22 to assemble, and another 2-T EMAT emission sensor of ultrasonic waves and another sensor EMAT for receiving 2-R ultrasonic signals on the opposite side of the chamfer (2-R / 2-T / 2-T / 2-R configuration).

Finally, the configuration of FIG. 3 is close to that of FIG. 3C with the same number of EMAT sensors on either side of the chamfer, with a reversal in the positioning order of each side of the chamfer (configuration 2- T / 2-R / 2 R / 2-T).

In connection with FIGS. 4 and 5, an example embodiment of the method according to the invention will now be described when an annular weld bead 24 deposited in several passes is inspected in a chamfer 18 (also annular) formed between two tubular conduits 20, 22 placed end to end.

In this exemplary embodiment, the method implements four EMAT sensors 2, arranged with respect to the weld bead according to one or the other of the configurations of FIGS. 3C or 3D.

The EMAT sensors 2 are more precisely carried by a carriage 28 which is movable relative to the pipes 20, 22 (and therefore with respect to the weld bead 24).

More specifically, the carriage 28 carrying the EMAT sensors moves automatically in a circumferential direction (relative to the axis of revolution XX of the chamfer 18) following the movement of a carriage carrying the welding electrodes. arc (not shown in the figures) so as to inspect the pass being deposited in the chamfer.

As the arc welding electrodes move circumferentially around the chamfer to deposit a weld bead pass, the EMAT ultrasonic wave emitting sensors emit ultrasonic waves toward the pass portion of the electrode. welding which has just been deposited and the ultrasonic signal receiving sensors EMAT receive the ultrasonic signals transmitted and / or reflected in said pass portion. Thus, it is possible to carry out a real-time inspection of each pass of the weld bead 24 during their deposition and to detect and dimension in real time any defects present in the passes.

The carriage 28 carrying the EMAT sensors is moved via an electric motor 29 automatically and synchronously with respect to the mobile carriage carrying the arc welding electrodes so as to follow the circumferential movement thereof.

Furthermore, it will be noted that the carriage 28 carrying the EMAT sensors moves in a circumferential direction about the axis of revolution XX of the chamfer along an annular guide strip 30 which is positioned on one of the tubular conduits ( here driving 20).

The presence of this guide strip 30 makes it possible to maintain a perfect alignment of the EMAT sensors with respect to the chamfer 18. This guide strip also makes it possible to maintain the carriage 28 (and therefore the EMAT sensors 2) in any angular position around the axis XX.

In addition, the carriage 28 carrying the EMAT sensors is advantageously coupled to a rotary encoder 32 so as to obtain the angular position of the EMAT sensors with respect to the axis of revolution X-X of the chamfer. The acquisition of this data makes it possible to determine the precise circumferential location of a defect detected in the pass of the weld bead being deposited.

FIG. 6 represents an alternative embodiment of the implementation of the method according to the invention for the inspection of an annular weld bead 24 deposited in several passes in a chamfer 18 formed between two tubular conduits 20, 22 put end to end.

In this variant embodiment, the method can implement four EMAT sensors 2 (arranged with respect to the weld bead according to one or other of the configurations of FIGS. 3C or 3D) which are carried by a mobile carriage 28 'by relative to the lines 20, 22.

With respect to the embodiment of FIGS. 4 and 5, this carriage 28 'also carries the arc welding electrodes 34. More specifically, the EMAT sensors 2 are arranged upstream with respect to the arc welding electrodes 34 (in the circumferential direction of the carriage 280-

This carriage 28 'moves automatically via an electric motor 29' in a circumferential direction with respect to the axis of revolution XX of the chamfer 18 so as to allow, on the one hand, the welding electrodes to the arc to deposit a weld bead pass in the chamfer, and secondly to the EMAT sensors to inspect in real time the pass being filed. In this variant embodiment, the EMAT sensors move with the arc welding electrodes, necessarily having the same speed of displacement as these (and keeping the same angular distance with respect thereto).

As the cart moves circumferentially

28 ', the welding electrodes 34 deposit a weld bead pass in the chamfer and, at the same time, the EMAT ultrasonic wave emitting sensors emit ultrasonic waves towards the portion of the weld pass that has just been deposited while the ultrasonic signal receiving EMAT sensors receive ultrasonic signals transmitted and / or reflected in said pass portion. It is thus possible to carry out a real-time inspection of each pass of the weld bead during their deposition and to detect and dimension in real time any defects present in the passes successively deposited in the chamfer.

In this variant, it will be noted that the carriage 28 'moves in a circumferential direction around the axis of revolution XX of the chamfer along an annular guide strip 30' which is positioned on one of the tubular conduits ( here driving 20).

Whatever the embodiment, the inspection method according to the invention advantageously provides different actions in case of detection of a defect in a weld bead pass during deposition.

The use of Rayleigh type surface waves makes it possible to detect various defects in a weld bead pass, namely in particular: the lack of penetration, the lack of melting on the chamfer or between the different passes, the cracks and the porosities.

In addition, the characteristics of the detected defects, namely in particular the type of defect and its dimensions, can be obtained in a manner known per se by the analysis of the ultrasonic signals received by the ultrasonic signal receiving sensors EMAT.

FIGS. 7 and 8 each show an exemplary representation of the ultrasonic signals received by the ultrasonic signal receiving sensors EMAT during the implementation of the previously described inspection method applied to a cord of weld deposited in several passes in an annular chamfer formed between two tubular conduits placed end to end.

These figures show a curve C which is a representation of the energy level (in decibel or in energy ratio) of these ultrasonic signals by the receiving EMAT sensors with respect to the circumferential position of the EMAT sensor around the axis of revolution of the annular chamfer.

In FIG. 7, two energy threshold level lines are also represented, namely a low threshold line I_i and a high threshold line L ₂ . When the curve C passes below the low threshold line Li, the operator or the welding system receives an alert signal indicating that a defect is being created in the weld pass being filed. . When the curve C passes below the high threshold line L ₂ (case for the dark parts in FIG. 7), the operator or the system receives another signal enabling it to conclude that the EMAT sensors have detected an anomaly and a defect has been created in the weld pass being filed. These threshold level lines Li, L ₂ can be obtained by feedback or simulation, and can be adapted according to the principle of machine-learning, which can be applied to the processing of ultrasonic signals. recorded.

In FIG. 8, two other energy threshold level lines are also represented, namely a low threshold line L'i and a high threshold line L ' ₂ . Compared to FIG. 7, these threshold lines are not rectilinear but curved, since they follow and adapt to the fluctuations of the curve C, in addition to self-adapting to the data obtained by feedback or by simulation according to the machine-learning principle applicable to the recorded ultrasound signals.

When curve C goes below the low threshold level line i, the operator or welding system is alerted by a warning signal that a fault is being formed in the current pass deposit. When the curve C exceeds the high threshold level line L ' ₂ , the operator or the welding system concludes that the EMAT sensors have detected an anomaly and a defect has been created in the pass of welding being filed. These threshold level lines Ι_Ί, L ' ₂ can be obtained by feedback or simulation.

If the energy threshold level line L _u L ₂ (for Figure 7) or Ι_Ί, L ₂ (for Figure 8) is exceeded (downwards), the operator or the welding system automatically receives an alert message. This warning message can then trigger (either automatically or through the operator) an adapted modification of some of the welding parameters in order to correct in real time the drop in the energy level of the curve C , and thus remedy the corresponding defect in the pass being filed. For example, the non-point reception of half of the energy emitted by an EMAT probe will potentially be representative of a lack of fusion failure, linked to an unsuitable speed or oscillation of the welding electrode.

This real-time modification (either automatically or through the operator) of certain parameters of the welding process may include modifications of the following parameters: amperage (intensity) and voltage (voltage) of the electric arc , welding speed, oscillation (ie positioning) of the welding electrode, and inert gas flow injected to create a protective halo. This modification can thus make it possible to remedy the defect detected during the inspection by modifying the welding parameters which are linked to the creation of such a defect.

Alternatively, when an alert message is sent to the operator or welding system to signal an overflow (downward) of the high energy threshold level line L ₂ or L ₂ , the welding operation can also be interrupted (either automatically or through the operator) to allow the operator or a mechanized system to remove the last filed pass (which has the fault that has triggered issuing the alert message).

Claims

1. A method of automatically inspecting a weld bead (24) deposited in several passes (P) in a chamfer (18) formed between two metal parts (20, 22) to be assembled, the different passes of the weld bead being deposited by means of welding electrodes (34) moving along the chamfer, the method comprising the following steps:

positioning at least one electro-acoustic ultrasonic wave emission sensor (2-T) on one side of the chamfer and at least one electro-acoustic ultrasonic signal receiving sensor (2-R) on an opposite side of the chamfer, the electro-acoustic ultrasonic wave emitting sensor being configured to emit Rayleigh surface waves;

activate the electro-acoustic sensors during their movement to enable the electro-acoustic emission sensor to generate and emit Rayleigh waves in the direction of the pass of the weld bead being deposited, the electro-acoustic reception sensor receiving ultrasonic signals transmitted and / or reflected in said pass;

and

repeat the operation for the entire weld bead pass.

2. Method according to claim 1, further comprising, on reception of ultrasonic signals characteristic of a defect in the pass being deposited by the electro-acoustic sensor, the modification during the pass of certain parameters of the welding in order to correct said defect.

3. The method of claim 2, wherein the change during the pass of certain welding parameters is performed by an operator.

4. Method according to claim 2, wherein the change during the pass of certain welding parameters is performed automatically according to an automatic learning mode classes and examples of welding defects. 5. Method according to any one of claims 1 to 4, wherein the Rayleigh surface waves generated by the electro-acoustic ultrasonic wave emission sensor are waves transmitted at a frequency between 200 kHz and 4,

5 MHz.

6. A method according to any one of claims 1 and 5, wherein the process steps are repeated for each pass (P) of the weld bead (24) deposited in the chamfer (18).

7. Method according to any one of claims 1 to 6, wherein the electromagnetic-acoustic sensors (2-T, 2-R) are kept in permanent contact with a surface of one of the two parts to be assembled so as to avoid any loss of signal during the inspection.

8. Method according to any one of claims 1 to 7, further comprising, on reception of ultrasonic signals characteristic of a defect in the pass being deposited by the electro-acoustic sensor, the automatic transmission of a signal. alert.

9. Method according to any one of claims 1 to 8, wherein the parts to be assembled are tubular conduits placed end to end, the chamfer having an annular shape.

The method of claim 9, further comprising, for the duration of the inspection, acquiring the angular position. electromagnetic-acoustic sensors with respect to the axis of revolution (XX) of the chamfer (18) so as to determine the circumferential location of a possible defect in the pass of the weld bead being deposited.

The method according to claim 10, wherein the acquisition of the angular position of the electro-acoustic sensors is performed by means of a rotary encoder (32) coupled to a movable carriage (28; 280 carrying the electromagnetic sensors). acoustic.

12. The method of claim 11, wherein the carriage carrying the electromagnetic-acoustic sensors is connected to a carriage carrying the welding electrodes to move therewith during the deposition of a weld bead pass.

13. Method according to one of claims 11 and 12, wherein the movable carriage carrying the electromagnetic-acoustic sensors moves in a circumferential direction around the axis of revolution of the chamfer along an annular guide strip ( 30; 30 ') positioned on one of the tubular conduits.

14. The method of claim 13, wherein the movable carriage carrying the electromagnetic-acoustic sensors moves along the guide strip via an electric motor (29; 29 ') while being able to be maintained. stationary in any angular position.

The method according to any one of claims 1 to 14, wherein the electro-acoustic sensors comprise an electromagnetic-acoustic transducer for receiving ultrasonic signals and an electro-acoustic transducer for emitting ultrasonic waves positioned on one side. chamfer, and another electro-acoustic transducer for receiving ultrasonic signals positioned on the opposite side of the chamfer.

The method according to any one of claims 1 to 14, wherein the electro-acoustic sensors comprise an electro-acoustic transducer for receiving ultrasonic signals and an electro-acoustic transducer for emitting ultrasonic waves positioned on one side. chamfer, and another electro-acoustic transducer for receiving ultrasonic signals and another electro-acoustic transducer for emitting ultrasonic waves positioned on the opposite side of the chamfer.