FR2598950A1 - Welding device for working in steam generators - Google Patents

Abstract

The welding device comprises two autonomous parts: a flexible torch composed of two rigid parts with a flexible intermediate part 59, and a gripping tool including a tubular passage which enables the torch both to rotate and to be supplied with electrical current. The torch is entirely insulated except in the region of its cylindrical terminal 64 which is gripped by the cams 80 supplying current. These cams are mounted in a rotationally controlled rotor 85 in a stator 87. The welding shielding gas is supplied via the flexible supply lead (umbilical) 71 of the torch, the current being supplied to the stator and the cams via the braid 90. This device is intended for repairing steam-generator tubes GV of nuclear reactors by welding either of internal sleeves or of a new tube end.

Description

WELDING DEVICE FOR INTERVENTION IN STEAM GENERATORS
The invention relates to a welding device intended for the repair of steam generator (SG) tubes of nuclear reactors # by welding either of internal sleeves, or of a new end of tube, by remote handling.

These cuffs cover any cracks or pitting, in order to restore the sealing of the tubes; and they are welded either clapboard or "nail" (that is to say by forming a welding bath which passes through a running part of the cuff) on the tube. When a tube end is replaced, the damaged part is cut and extracted and a new, healthy section is welded together.

Due to the lack of recoil in front of the tube plate, especially in the peripheral zone, it is necessary to use "flexible" tools.

The design and construction of these flexible devices pose difficult technological problems, in particular by the lack of recoil inside the water boot, by the weight and the inertia of the power cables which disrupt the proper functioning of the systems. drive of miniaturized tools, and the need to regularly have to quickly readjust the quality of the welding electrode as and when welding.

The present invention relates to a "flexible" welding device allowing access to the entire surface of the tube plate, which is freed from wiring problems and which responds to the demands of rapid sharpening of the electrode as and when of the intervention.

It is characterized by the fact that the welder is broken down into two completely separate parts: on the one hand an easily and quickly removable part (the welding torch itself), on the other hand an on-board part (the "spinner" of drive) on the positioning remote manipulator. It is characterized by the fact that the electrical connection of the electrode is made at the drive mechanism.

In Figure 1 is shown schematically a steam generator (GV) with its tubes in
U 903, its tubular plate 902, the bowl 901 where the interventions are carried out and the partition plate 904; the access manhole 905 and the primary circuit pipe 906.

Figures 2a, b describe the removable welding torch.

Figure 3 shows the tightening, drive and power supply spinner.

In Figure 4a is shown the welding device mounted on a remote manipulator placed in the GV bowl. In Figure 4b we see the welding torch mounted in the "spinning" drive.

FIG. 5 represents a variant of the torch / "spinner" assembly, where the electrical and neutral gas supply to the torch is ensured by the spinner on board a remote manipulator.

In FIG. 2a, the welding tata is arranged for a sided weld of the cuff 50 on the tube 51. The electrode 52 is positioned opposite the upper end of the cuff. The welding head comes to bear on the base 53 of the cuff.

The welding torch comprises an upper rigid part, an intermediate flexible part and a lower rigid part. It is extended by a neutral gas supply hose.

The upper rigid part comprises an insulating nose 54, a conductive bar 55 on which the electrode 52 is fixed, a gas diffuser 56 made of insulating material, an insulating tubular spacer 57 on which is screwed a metal connector 58 connecting to the part flexible intermediate. This spacer is pierced with orifices 65 for the circulation of neutral gas.

The intermediate flexible part comprises an external hose 59 for confining the gas, a metallic braid 60 for electrical supply which is connected to the bar 55. This flexible part extends below the tubular plate 61.

The electrical supply braid 60 is provided over its entire length with a heat-shrinkable insulating sheath 72.

The lower rigid part (FIG. 2b) comprises: a metal connector 62 for connection to the flexible sheath 59, an insulating spacer 63, a cylindrical connector 64 on which the braid 60 is welded. This connector is pierced with orifices 66 for circulation of gas. It is connected to an insulating ring 67 in which is mounted a rotary passage composed of two parts 68 and 69 mounted on self-lubricating rings 70.

The gas supply hose 71 is connected to 69. Thanks to this rotary passage, the hose 71 is not rotated by the welding torch.

The spinner (fig.3) performs three functions: gripping the torch, rotating it, and supplying power to the torch.

The gripping is provided by clamping cams 80, the opening and closing of which are controlled by driving a pinion 81 actuated by a rack 82 with pneumatic double-acting control. A rotating manifold with its three seals 89 ensures the pneumatic supply.

The rotary drive is controlled by the motor 83 driving a set of pinions 84 connected to the rotor 85 which supports the cams 80. An encoder 86 assists in the programming of the welding. your mobile part is contained in a "stator" 87; the whole is enclosed in the insulating casing 88.

The electrical terminal 90 is fixed to the stator 87, the current is transmitted to the rotor 85 by friction according to conventional means; and arrives on the metal clamping cams which feed the welding torch.

Figure 4a shows schematically the implementation of the welding assembly by a remote manipulator 91 serving the tube plate 902 of the GV.

A roller presser 93, clamping on the flexible umbilicus 71, engages the welding head in the tubular plate, through the spinner 92. The hose 71 as well as the power cables 94 of the remote control device are arranged in a loop in the bottom of the GV to, in part, lighten --3e their weight the manipulator.

In Figure 4b is shown the torch mounted in the spinner.

When the welding head 59 is engaged in abutment in the tube to be treated, the cylindrical connector 64 is engaged at the level of the clamping cams 80 integral with the rotor 85, the assembly rotating in the strator 87.

FIG. 5 represents a variant of the torch / spinner assembly, where the torch is introduced frictionally into the spinner and behaves like an electric pin. The contacts and the friction are provided by elastic metal strips 95 carried by the connector 64 of the torch.

 The metal rotor 96 is immersed in an electric mercury collector 97.

This arrangement makes it possible to avoid seals between the rotor and the stator and therefore to reduce friction.

As a variant, these flexible strips will be integrated into the spinner, and the torch would not have any.

The welding gas is also supplied at the level of the torch by a distribution groove 98 formed in the spinner. Sealing yeast seals 99 seal the gas circuit.

Under these conditions, there is no need to add an umbilicus to the welding torch, a short flexible extension is sufficient for the vertical motorization at the level of the presser 93.

Under these conditions the torch is obviously completely freed from the weight and twists of the power cables since these are no longer connected to it.

Claims (1)

Claim 1: Welding device intended for repairing steam generator tubes (GV) of nuclear reactors by welding either internal sleeves or a new tube end, by remote handling, allowing access to the entire surface of the tube plate. It is characterized in that it consists of two completely distinct, separate parts, namely: on the one hand a welding torch, easily and quickly removable from the device (the welding torch itself), on the other hand a rotational drive device ("spinner"), which is on board the positioning manipulator; and that electrical connections necessary for welding are established between these two parts. Claim 2: Welding device according to claim 1, characterized in that the welding torch comprises three parts: a rigid head carrying the electrode 52, a flexible part 59, a rigid lower part provided with a metal body 6A on which takes place the arrival of electric welding current; and that it is entirely externally isolated except for this connector 64. Claim 3: Welding device according to claim 1, characterized in that the rotary drive device performs three functions: gripping the torch, its rotary drive, the electrical supply of the torch. Claim 4: Welding device according to claim 2, characterized in that the welding torch is connected in its lower part to a flexible pipe 71 for supplying gas by a rotary passage composed of two parts 68 and 69 mounted on self-lubricating rings 70. Claim 5: Welding device according to claim 3, characterized in that the rotary drive device grips the torch by clamping cams 80 also serving as electrical terminals for transmitting current to the connector 64 of the torch. Claim 6: Welding device according to claim 2, characterized in that the welding torch comprises flexible metal strips 95 which establish the electrical contact inside the spinner.  Claim 7: Welding device according to claims 3 and 6, characterized in that the rotary drive device ensures the electrical contact and the gripping of the torch by the introduction of the soft friction torch through the drive device, the friction being achieved by means of flexible strips 95 carried by the torch or by the spinner. The spinner is also provided with a rotating mercury collector 97 allowing rotations without friction. Claim 8: Welding device according to claim 3, characterized in that the rotary drive device comprises a gas distribution 98 directly feeding the welding torch.