GB2172533A - Improvements in or relating to underwater welding apparatus - Google Patents

Abstract

The disclosure relates to an underwater welding apparatus for welding a component (9) to a pipe consisting of a chamber (10) for mounting on the pipe and having a bottom part open to the pipe. The chamber has a supply (65, 66, 67) for delivering argon to the chamber to displace water therefrom, a central mounting (37) for the component to be attached to the pipe and an electric welding gun (48) mounted on a hub (57) to rotate around the mounting (37) by means of an electric motor (52) to rotate the gun around the base of the component on the pipe to weld the base to the pipe. <IMAGE>

Description

SPECIFICATION Improvements in or relating to underwater welding apparatus The invention relates to underwater welding apparatus and is particularly although not exclusively applicable to welding studs to tubular structures underwater.

Conventionally welding is carried out under water using specialist welding equipment designated to operate underwater but such equipment requires highly qualified welder/divers to operate and is also cumbersome and awkward to move from location to location where welding operations are to be performed.

Apparatus has been devices for electric arc welding joints in metal pipes at deep underwater locations in which the joint to be welded is enclosed in a chamber into which pressurised gas is introduced to displace the water from the chamber. The chamber is equipped with welding apparatus and is large enough to accommodate a diver who operates the equipment within the chamber on the area to be welded. U.K. Patent Specification No. 1241466 discloses such apparatus.

The invention provides underwater welding apparatus for welding of a component to a body, the apparatus comprising a chamber for attachment to the body and providing a welding enclosure with an opening to encircle the area to which the component is to be applied in direct communication with the welding enclosure, means releasably to mount a component to be attached to the body in the welding enclosure, means to supply an inert gas to the enclosure to displace water from the chamber and remotely controllable welding means in the body for welding a component held in the mounting means to the surface of the body in said opening.

It will be understood that the above apparatus provides a dry environment in which a remotely controlled welding device can be operated to perform a welding operation without the need for the specialist skills of a welder/diver.

Remotely controllable means may be provided in the chamber for moving the welding means whilst performing a welding operation to create a line of weld between the component and body.

More specifically remotely controlled drive means may be provided for moving the welding means in a circular path around the component to be welded to the body to create an annular line of weld between the component and body.

The means to mount the component to be attached to the body in the enclosure may comprise a socket having gripping means to receive and hold the component to be attached to the body, the socket facing towards said opening in the chamber to locate the component with the face of the component against the body.

The welding means may be mounted coaxially with the socket to rotate around the axis of the socket and remotely operable drive means are provided for causing the welding means to revolve around the axis when performing a welding operation to create an annular weld between the component and body to which the component is to be attached.

The welding means may comprise an inert gas arc welding device and the drive means for rotating the welding device comprises a motor driven rotary hub on which the welding device is mounted and means to supply electrical power and inert gas via the hub to the welding device.

In one specific construction the rotatable hub may comprise an inner wall of a non-rotating annular gas tight compartment mounted in the chamber, the hub having an encircling slip ring assembly electrically connected to the welding device on the hub and with which contact means mounted in the compartment for connection to a remote source of electrical power engage.

The compartment may having a connection for supply of an inert gas to the compartment means may be provided for the supplying inert gas from the compartment from the welding device.

Further, the means to rotate the hub may comprise an electrical hydraulic or air pressure drive motor mounted on the non-rotating enclosure and drivably connected to the hub.

The chamber may have an inlet connection to said further supply of inert gas to the welding enclosure and a heater may be provided for heating the gas.

The annular compartment may be formed with the socket to receive the component to be welded to the body and a socket guide extends from the socket through the rotatable hub towards the opening in the chamber to support the component, the rotatable hub being supported in bearings spaced apart along the socket guide.

Means are provided for adjusting the hub/ compartment towards and away from the chamber opening to enable a jet of inert gas from the welding device to be directed on to location on the body to which the weld is to be applied to dry the body.

The adjustment means may comprise a lead screw rotatably connected at one end to the enclosure and engaged in a nut mounted on the chamber whereby rotation of the lead screw moves the compartment and with it the socket for the component towards and away from the opening from the chamber to the body to which the component is to be attached.

A source of illumination is mounted in the chamber and the chamber has a viewing port to enable the weld operation to be viewed or to receive a camera for recording the welding operation.

The chamber may have an adaptor plate encircling the opening in the chamber to conform to the shape of the body to which the chamber is to be attached for the welding operation.

The following is a description of some specific embodiments of the invention, reference being made to the accompanying drawings in which: Figure 1 is a partly section partly elevation view through an underwater welding apparatus; Figure 2 is an exploded perspective view of the components of the apparatus shown in Figure 1; Figure 3 illustrates the apparatus in preparation for use; Figure 4 is a diagrammatic view of a further form of the apparatus; and Figures 5 to 8 illustrate modified forms of the apparatus.

Referring firstly to Figures 1 and 2 of the drawings, there is shown an underwater welding apparatus intended particularly for welding components such as an anode studs 9 to an underwater pipeline. The apparatus comprises an upright cylindrical chamber 10 having an open top 11 and an encircling top flange 12. Vertical ribs 13 are formed on the outer side of the chamberto strengthen the chamber wall. The bottom end of the chamber has a bottom wall 14 formed with a large central aperture 15 encircled by rim 16. In order to apply the device to the curved wall of a pipeline, an adaptor plate or saddle 17 (described with reference to Figure 3 below) is mounted on the underside of the chamber with a concavely curved recess 18to receive the surface of the pipeline and a central aperture 19 to align with the opening 15 ofthe chamber.The curved recess 18 has an annular groove 18a encircling the opening 15 on which a seal 1 8b of open cell neoprene rubber is mounted to seal with the pipeline. It will be appreciated that different adaptor plates or saddles are provided for different diameter pipes or flat or otherwise shaped surfaces.

At the top of the chamber a strong back or bar 20 extends diametrically across the chamber and is secured at its ends to the flange 12 by bolts 21. A brass collar 22 is mounted centrally in a bore in the strong back and has an internal screw thread in which a vertically extending lead screw 23 is mounted. Thumb bars 24 are mounted at the upper end of the lead screw for rotating the screw and the lower end of the lead screw is held captive to a plug 25 by a plate 26 secured to the plug and engaging in an annular slot 27 around the lower end of the lead screw.

The plug 25 is screwed into a bore 28 formed in a circular top wall 29 of a gas-tight enclosure indicated generally at 30 and extending across the chamber 10 and supported by the lead screw in the chamber. The enclosure has an outer annular wall 31 having an upper flange 32 to which the top wall 29 is secured by bolts 33. An O-ring seal 34 is provided between the top of the flange 32 and the underside of the top wall 29 and further O-ring seals 35 and 36 are mounted in spaced annular recesses encircling the annular wall 31 to engage the inner surface of chamber 10.

The enclosure has an innerannularwall 37 extending downwardly from the centre of the top wall 29 around the screwthreaded bore 28 coaxially with the axis of the lead screw 23 and the axis of the opening 15 at the bottom of the chamber. The bore of the upper part of the annularwall 37 forms a continuation of the bore 28 in the enclosure top wall 29 and a rubber socket 38 is mounted in the bore having a plurality of inwardly facing resilient flanges 39 to receive and hold the upper end of the stud to be attached to the pipeline. The tubular wall has a lower reduced diameter part 37 which guides and supports the stud component held in the socket 38.

An annular hub 40 encircles and is rotatably mounted in upper and lower bearings 41, 42 mounted on the upper and lower parts of the tubular wall 37. The hub 40 is supported vertically by the bearing 42 the inner race of which is supported in a recess 43 in the outer surface of the lower housing wall 37b and is held in position from below by washer 44 secured by a nut 45 and lock nut 46 screwed on to the housing.

The hub 40 has a downwardly and outwardly swept hollow arm 47 at the lower end of which is mounted an inwardly and downwardly angled tungsten welding device 48 to operative end 49 which is disposed beneath the lower end of the tubular housing 37 adjacent the location where the weld is to be formed on the pipeline. The arm 47 has an electrical power connection to the electrode of the welding torch and also a gas supply passage indicated at 50 for supplying gas (e.g. argon) to the welding head to issue around the electrode during the welding operation.

The upper end of the hub 40 is formed with an integral annular gear 51 and an electric drive motor 52 is mounted on the top wall of the gas tight enclosure 30 and has an output shaft 53 extending through an aperture 54 in the wall and carrying a drive pinion 55 engaging the annular gear 51. The motor is connected by electrical power leads to a source of power at the sea-surface. Instead of an electric motor, a hydraulically driven motor or an air pressure motor may be utilised with appropriate connections to a power source at the sea surface.

Rotation of the motor turns the hub and thereby moves the welding head 49 around the location where the weld is to be formed on the pipeline. In order to maintain current supply to the welding head an insulating sleeve 56 is secured to the hub 40 and a slip ring 57 is mounted on the sleeve with an electrical connection direct to the electrode of the welding device. The slip ring receives power from a contact assembly 58 mounted in the enclosure and having a power supply lead extending from the seasurface through a sealed aperture (not shown) in the top wall 29 of the enclosure.

The enclosure 30 has an integral bottom wall 59 which encircles an insulated part of the slip-ring assembly on the hub 40 and is formed with a seal 60 engaging the assembly. Inert gas is pumped to the enclosure 30 through a conduit 61 extending through a sealed opening in the upper plate 29 from the sea surface to fill the enclosure and supply gas through the passage 50 into the welding device 48.

The bottom wall 59 of the compartment also has a bulb socket 62 to receive a bulb 63 projecting downwardly to illuminate the weld area. Power for the socket is supplied through a power line extending from the sea-surface.

A further supply of inert gas 65 (e.g. argon) from the sea-surface is connected to a tubular connector 66 mounted at the lower part of the chamber 10 and incorporating an electrically powered glow plug heater or heaters 66a (See Figure 2) for pre-heating the gas. The connector has a discharge nozzle 67 which discharges the gas into the aperture 15 to displace water from the chamber below the gas tight compartment 30 over the weld area out through a drain hole 68 disposed diametrically opposite the connector 66. The heater gas also dried the surface of the pipeline where the weld is to be formed. The chamber is maintained with a positive gas pressure during the welding operation to prevent an ingress of water.

The chamber has a downwardly and inwardly angled viewing port 69 disposed in the chamber wall at a location spaced around the chamber from the connector 66 and having a clear window 69a therein and a further port 70 is formed in the chamber wall diametrically opposite port 69to which a television or video camera may be connected for viewing or recording the welding operation. A plug is provided for port 70 when it is not required for use by a camera.

Referring now to Figure 3 of the drawings, the adaptor plate 17 for attaching the chamber 10 to an underwater pipeline 9 is illustrated. The adaptor has a pair of corner brackets 17a which extend over electro-magnetically operated clamps 8 secured to the pipeline on opposite sides of the area where a stud is to be attached. The brackets are attached to the clamps by means of screw clamps 7 to lock the adaptor plate in place on the pipeline to receive chamber 10 as described earlier.

The apparatus is used in the following manner.

The stud 9 or other component to be attached to an underwater pipeline is located in the socket 38 in the chamber with the end of the stud projecting from the stud guide into the aperture 15 of the chamber.

The base of the stud incorporates a square section washer which becomes the filler material for the weld. The chamber 10 is then secured to the pipeline as described above with the base of the stud in alignment with the location where it is to be fixed to the pipeline. The apparatus can be utilised on any part of the pipeline or at any position on a flat or otherwise shaped surface.

Inert gas to the housing 66 is then switched on from the sea-surface to displace water from the lower part of the chamber below the enclosure 30, the water being displaced out through drain aperture 68. The inert gas is heated as it is passed into the chamber to dry the pipeline ready for the welding operation. Once all the water has been driven out and the pipeline is dry, the diver adjusts the lead screw 23 to bring the base of the stud and a filler washer on the base on to the pipeline ready for the welding operation to be performed. The current and gas supplies to the welding device are then switched on to start the welding operation and the motor 52 for rotating the hub supporting the tungsten welding device is also switched on to move the welding device around the base of the stud.These operations can also be viewed by the diver through the viewing port and also at the seasurface via the television/video link.

To initiate a welding arc, a series of high frequency pulses is transmitted down the welding cable from the surface welding machine. On reaching the gap between the tungsten welding device and the filler washer the pulses create a spark which establishes the welding arc. When the welding device has performed a complete revolution around the component forming a weld around the full periphery of the stud base, the welder is switched off and the apparatus is moved to the next site where a welding operation is required.

All the various gas and power lines for the apparatus described above are collected into a single umbilical which extends to the sea surface where the various lines are connected to gas and power supplies.

Figure 4 of the drawings shows a similar but simplified version of the apparatus and like parts have been allotted the same reference numerals. In the apparatus of Figure 3 the chamber is of box form and the aperture 15 in the lower part of the chamber has a downwardly extending L-section flange on the underside of which is formed a seal to engage with the surface of the pipeline to which the stud is to be attached. A further difference lies in the position of the drive motorforthe rotary hub which, in the Figure 3 embodiment is inverted and drive the hub through intermediate gearing indicated at 70. Also, the inert gas supply for the welding device 48 is fed to the device through the rotary hub. The arrangement is otherwise similar to that described above.

It will be understood that in the apparatus described above, all welding parameters are controlled from the sea surface. The washer material and welding parameters can be altered to suit the individual applications. Diver involvement is limited to attaching and securing the unit to the pipe line at the location where the stud is to be welded to the pipeline. The design of the stud can of course be altered to take into account any electrically sound connections which may be required.

Reference is now made to Figures 5 and 6 of the accompanying drawings which show a similar welder to that of Figures 1 and 2 and like parts have been allotted the same reference numeral.

In the construction shown in Figure 5, the welding deviced 48 is.mounted on a pivoting arm 84 which extends across the chamber immediately below the hub 40 the welding device being located towards one end 84a on the arm. The other end 84b of the arm is supported by means of a hinged joint 85 attached to the lower end of one side of the hub 40 to allow the arm to swing towards and away from the bottom of the chamber. An adjustable screw stop 88 is fixed mounted along the arm to bear against the underside of the hub 40 diametrically opposite the joint 85 to limit upward movement of the arm and a tension spring 87 is attached at one end to the arm and at its opposite end to an anchorage 89 on the hub 40 to hold the arm in the upper limit of its travel with the stop 88 against the hub. The welding device 48 is attached by means of a bracket 90 to the arm 84 adjacent said end 84a thereof. At the end 84a of the arm, there is an outwardly extending striker plate 86 which lies in the path of a domed cam 91 mounted on the underside of the enclosure 30'above the striker plate. The cam is mounted on a push-rod 92 extending through a sleeve 93 in the enclosure and the upper end of the push-rod carries a push-button 94 biassed upwardlyfromthetopwall 29 of the enclosure by a compression spring 95. Depression of the button 94 presses the cam 91 against the striker plate 90 and thence presses the arm 84 downwardly against the action of the tension spring 87. The welding device 48 is thereby moved into immediate proximity with the perimeter of the stud 9 to be welded to the pipeline.This is required for initiating the welding arc between the electrode 48a of the welding device 48 and the weld area at the perimeter of the stud. This is particularly important when the welding device is used at considerable depths which require the weld chamber to be subjected to high internal pressures. When the argon atmosphere in the chamber is highly compressed, the gas molecules are, consequently, packed tight together and this can inhibit the initation of the welding arc.By moving the welding device to bring the electrode of the device into close proximity or just touching the filler washer around the perimeter of the stud where the weld is to be formed, the arc can be established and the push button 88 can be gradually released to extend the arc until the welding device has returned to its normal operating position as shown in Figure 5 with the abutment 49 engaging the underside of the hub 40. The hub is then rotated to pass the welding device around the perimeter of the stud to form a complete weld around the stud as before.

A number of further modifications are incorporated in the apparatus of Figure 5. Firstly the docking plate 17 is bolted directly to an encircling flange 100 around the lower periphery of the outer housing 10. A drain valve 101 is provided in the docking plate itself for release of water accumulated on the top of the pipe. The bulb socket 62 is mounted in a downwardly inclined port 102 in the side of the chamber instead of being mounted on the lower wall of the inner enclosure. The housing has a side manifold 95 (see Figure 6) to which the argon supply cable is connected and having a discharge nozzle 67 into the chamber 10 below the enclosure 30. A pair of glow plug 103 are mounted in the housing and are connected to a cable supply 104 to the surface to heat the argon passing through the manifold.

Figures 7 illustrates a further embodiment according to the invention for welding a washer to a pipeline around the inner periphery of the washer.

In this case the welding device 48 is mounted on a central carrier 110 connected to the rotating hub 40 with the operative end of the welding device angled downwardly and outwardly with respect to the axis of rotation of the hub. The washer 111 to be attached to the pipeline is held in an annular guide 112 in position on the pipe line,the guide 112 being mounted on legs 113 extending downwardly from the underside of the enclosure 30. The arrangement is otherwise generally similar to the arrangement of Figures 1 and 2 described above.

It will be appreciated that in the above described embodiments the welding device rotates in a plane disposed above the location of the required line of weld of the stud or other component to the pipeline and as the welding device moves around the periphery of the stud, the gap between the electrode of the welding device and periphery of the stud will vary slightly. As the diameter of the component to be attached to the pipeline increases and the radius of the pipeline reduces so the gap between the welding device electrode and weld area will vary to a greater extent.

Figure 8 of the drawings to which reference is now made shows such a circumstance in which a relatively large diameter disc is to be welded to a relatively small diameter pipeline. Welding apparatus used as illustrated is generally similar to that described with reference to Figure 5 with the exception that an annular cam track 121 is mounted on the underside of the lower wall of the chamber 30 and the welding device 48 is provided with a guide roller 122 which bears on the underside of the track and is held in engagement therewith by the tension spring 87 connecting the arm 84to anchorage 89 on the hub 40. The adjustable abutment 88 of the earlier described embodiment on the arm is omitted.The track is shaped so that as welding device 48 is rotated around the disc 120 by the hub 40, the electrode 48A of the welding device follows the contour ofthe pipeline and is maintained at a constant distance from the required line of weld.

The push-button operated push-rod 92 for displacing the welding device 48 to bring the electrode of the device into close proximity or touching contact with the location at which the weld is to be formed for initation of the arc is provided as described in the previous embodiment but in this case the cam 91 at the lower end of the push-rod is omitted and a lug 122 is provided on the body of the welding device 48 adjacent the roller 121 to align with the push-rod 92. An aperture 123 is formed in the cam track 121 through which the push-rod can be extended to engage the lug 122 with which the welding device is aligned for initiation of the welding arc at the commencement of a welding operation. The arrangement is otherwise generally similar to that described with reference to Figure 5 and to Figures 1 and 2 above.

Claims (24)

1. An underwater welding apparatus for welding of a component to a body, the apparatus comprising a chamber for attachment to the body and providing a welding enclosure with an opening to encircle the area to which the component is to be applied in direct communication with the welding enclosure, means releasablyto mount a component to be attached to the body in the welding enclosure, means to supply an inert gas to the enclosure to displace water from the chamber and remotely controllable welding means in the enclosure for welding a component held in the mounting means to the surface of the body in said opening.

2. An apparatus as claimed in claim 1 wherein remotely controlled means are provided in the chamberfor moving the welding means whilst performing a welding operation to create a line of weld between the component and body.

3. An apparatus as claimed in claim 2 wherein remotely controlled drive means are provided in a certain path around the component to be welded to the body to create an annular line of weld between the component and body.

4. An apparatus as claimed in claim 3 wherein the meansto mountthecomponenttobeattachedtothe body in the enclosure comprises a socket having gripping means to receive and hold the component to be attached to the body, the socket facing towards said opening in the chamberto locate the component with the face of the component against the body.

5. An apparatus as claimed in claim 4whereinthe welding means is mounted coaxiallywith the socket to rotate around the axis of the socket and remotely operable drive means are provided for causing the welding means to revolve around the axis when performing a welding operation to create an annular weld between the component and body to which the component is to be attached.

6. An apparatus as claimed in claim wherein the welding means comprise an inert gas electrode arc welding device and the drive means for rotating the welding device comprises a motordnven rotary hub on which the welding device is mounted and means to supply electrical power and inert gas via the hubto the welding device.

7. An apparatus as claimed in claim 6 wherein the rotatable hub comprises an innerwall of a nonrotating annular gas tight compartment mounted in the chamber, the hub having an encircling slip ring assembly electrically connected to the welding device and with which contact means for connection to a remote source of electrical power engage.

8. An apparatus as claimed in claim 7 wherein the compartmenthasaconnectionforsupplyofan inert gas supply to the compartment and means are providedforsupplying gasfromthecompartmentto the welding.

9. An apparatus as claimed in claim 7 or claim 8 wherein the means to rotate the hub comprise a drive motor mounted on the non-rotating enclosure and drivably connected to the hub.

10. An apparatus as claimed in any of claims 7 to 9 wherein the chamber has an inlet connection tothe further supply of inert gas to the welding enclosure for displacing water from the welding enclosure, the inlet connection having a heaterforheatingthegas supplied to the chamber.

11. An apparatus as claimed in any of claims 7to 10 whereintheannularcompartmentisformedwiththe socketto receive the compartment to be welded to the body and a socket guide extends from the socket through the rotatable hub towards the opening in the chamberto supportthe component, the rotatable hub being supported in bearings spaced apart along the socket guide.

12. An apparatus as claimed in any of claims 7 to 11 wherein means are provided for adjusting the hub/ compartment towards and away from the chamber opening.

13. An apparatus as claimed in claim 1 2 wherein the adjustment means comprise a lead screw rotatably connected at one end to the compartment and engaged in a nut'mounted on the chamber whereby rotation of the lead screw moves the compartment and with itthesocketforthe compartmenttowards and away from the opening from the chamberto the body to which the component is to be attached.

14. An apparatus as claimed in any of claims 6to 13 wherein means are provided for mounting the welding device on the rotary hub for movement towards and away from said opening from the chamberwherethe component is supported against the body to which it isto be attached by welding, means being provided for permitting the movement of the welding device away from said opening to define a normal operating position of the welding device with respect to the opening, means operable from outside the chamber being provided for moving the welding device into close proximity with the opening to reduce the length of the are for striking the arc at the commencement of the welding operation and means being provided for returning the welding device to said normal operating position.

15. An apparatus as claimed in claim 14wherein theweiding device is mounted on a swing arm pivotally hinged to the hub, stop means being provided for limiting movement ofthe arm towards the hubto define said normal operating position and resilient means being provided for holding the arm in said operating position defined by the stop means.

16. An apparatus as claimed in claim 1 5 wherein the means for displacing the welding device towards said opening in the chamber comprise a push rod mechanism extending through the chamberto engage the arm or a part attached thereto and projecting through the chamber wall to receive a push button for displacing the rod to cause a corresponding movement of the arm and welding device towards said openings.

17. An apparatus as claimed in any of claims 14to 16 wherein a cam track is mounted around the chamberfacing towards said opening, said means being provided on the welding device or a part attached thereto to engage the cam track and biasing means being provided for holding the guide means in engagement with the cam track, the cam track being shaped to cause the welding device to move towards and away from the opening in the chamber as it rotates around the chamberto maintain a substantiallyconstantarogapwiththeweld linetobe created around the component to be attached to the body.

18. An apparatus as claimed in claim 17 and in the case where the welding device is mounted on a pivotally mounted arm supported on the hub, wherein the guide means for engaging the cam track comprise a roller mounted on the arm supporting the welding device and engaging the cam track and the means to hold the guide means in engagement with the cam track comprise a tension spring acting between the arm and hub.

19. An apparatus as claimed in claim 17 or claim 18 and in the case where a push rod mechanism is provided for displacing the welding devicetowards the opening for initially striking the welding arc, wherein the cam track is provided with an aperture through which the push rod passes to act on the arm on which the welding device is mounted to displace the welding device away from the cam track towards the opening chamber against the action of the resilient means.

20. An apparatus as claimed in any of the preceding claims wherein a source of illumination is mounted in the chamber and the chamber has a viewing port to enable the weld operation to be viewed or to receive a camera for recording the welding operation.

21. An apparatus as claimed in any of the preceding claims wherein the chamber has an adaptor plate encircling the opening in the chamber to conform to the shape of the body to which the chamber is to be attached for the welding operation.

22. An apparatus substantially as described with reference to and as illustrated in Figures 1 to 3 of the accompanying drawings.

23. An apparatus substantially as described with reference to and as illustrated in Figure 4 of the accompanying drawings.

24. An apparatus substantially as described with reference to and as illustrated in Figures 5 and 6,7 or 8 of the accompanying drawings.