Method and apparatus for welding pipes

0001The invention relates to a method and a device for welding pipes or tubes to each other for forming pipe lines for for instance oil or gas, as described in the preambles of claims 1 and 10, respectively. The invention particularly relates to welding stationary, lying pipes to each other.

0002Such a method and device are known from DE-A-39 37 094.

0003It is known to use a so-called line-up clamp to that end, which clamp is moved within the pipes until on either side of the weld to be formed, and which, at that location, is brought into clamping engagement with the inner surfaces of the ends of the pipes to be welded together. The frame on which the clamping means for both pipes have been arranged provides a rigid orienting means, as a result of which the pipes will be exactly aligned before welding. Such an arrangement is for instance shown in Dutch patent application 90.02396. Here, after orienting the pipes an annular supporting frame for the welding equipment is placed at the outside of the pipes, using a mounting belt arranged earlier on,on one of the pipes. For said technique, International patent application WO 95/21721 could also be referred to, in which document a line-up clamp which is mobile within the pipes is described.

0004The use of a line-up clamp which moves within the pipes requires special provisions, such as long operating lines, the length of which corresponds to the length of the pipe line made ready. Furthermore the line-up clamp has to be retrieved entirely in case it malfunctions. This results in considerable delays in the work.

0005It is an object of the invention to improve on this.

0006From one aspect the invention to that end provides a method for welding pipes to each other, as described in claim 1.

0007By letting the clamping means for the pipes to be welded together engage at the outside they can always be reached well and can be checked. The operating lines can remain short here, despite the fact that they have to make the movement of the frame possible. Moving the frame over the pipes makes it possible to use the pipes as a guide and a support, as a result of which the frame can be kept simple.

0008It is noted that from European Patent application EP 0 119 636 it is known to use a stationary frame for welding vertical pipes to each other, which frame comprises a cage construction with two coaxial sleeves in it for accommodation of the two pipe ends, in which at the outside of the sleeves two clamping jaws acting on the sleeves are provided for fixating the pipes in their positions. The frame is furthermore provided with welding means. After arranging a weld the clamping means are detached and the upper pipe is pushed downward until said pipe and the pipe placed on it are accommodated in their respective sleeves, after which the process can start over again.

0009Preferably use is made of rollers on or at the frame for engagement of the outer side of the pipes, in which the rollers can be rotated about an axis perpendicular to the centre line of the pipes, in which way a simple guiding and supporting means for the frame on the pipes is used.

0010Preferably the frame is moved over the pipes by means of driving means provided on the frame, such as a driven roller for instance. External provisions can be kept limited as a result.

0011Alternatively it is possible to pull the frame on a cable, in which case the frame can remain lightweight and the movement can take place more quickly.

0012Preferably at least a first connecting weld is made between the pipes by means of welding means that are supported on the frame. Here the frame is used for other purposes, whereas the frame also ensures movement of said welding means, so that no additional measures need to be taken.

0013In a further development of the method according to the invention, the welding activities are split up, to which end after making the first connecting weld the frame is moved to a next pipe transition, and the weld is finished with the help of external welding means, preferably simultaneously to the movement or the making of the next first connecting weld. The - relatively expensive- line-up part here is used no longer than strictly necessary and it can be used again quickly for a next welding process. The weld connection is sufficiently strong here for holding both pipes together. The weld can be finished with simpler welding means.

0014From a further aspect the shape of the one pipe is determined with the help of the first clamping means, said shape is stored in a memory as shape data, the second clamping means are brought into engagement with the other pipe and based on the shape data stored in the memory are urged into a position corresponding to the shape stored.

0015Thus it can be achieved that the contours of the end edges of both pipes have the same shape, so that the weld can be properly arranged and a reliable connection can be laid over the entire circumference. Pipes are usually a little deformed and different as to roundness, which by using the method according to the invention need not have detrimental effects any more, as the shape is now partly adjusted.

0016It is preferable here that after storing the shape data of the one pipe, the first clamping means are further operated until in a position in which the one pipe is clamped.

0017Preferably the second clamping means are operated to clamp the other pipe after said deformation movement.

0018From a further aspect the invention provides the measure that the first and second clamping means are arranged on two respective frame parts, which are connected to each other in an adjustable manner in pipe axis direction, in which the mutual axial distance of the end edges of both pipes is adjusted to the weld shape to be made.

0019From another aspect the invention provides a device for welding pipes to each other, as described in claim 10.

0020Preferably the means for guiding engagement of the outer side of the pipes are formed by rollers, for rolling support of the frame on the pipes.

0021Preferably the device according to the invention comprises welding means supported on the frame, such as in particular a welding robot guidance, and possibly means for welding gas supply and/or a welding wire supply. The service lines towards the device can be kept short and simple as a result. This may result in a largely independent combined aligning and welding device.

0022Preferably the clamping means comprise a circumferential series of clamping plates which can be radially retracted and extended, for direct engagement of the outer surfaces of the pipes. The division in clamping plates renders a better controllable clamping and aligning possible.

0023The initial placement is facilitated when the clamping means are arranged for a part of the circumference on a frame part which can be opened with respect to the rest of the frame, in which preferably the part of the frame that can be opened takes up approximately 180 degrees or more of the circumference in circumferential direction. As a result the entire frame can be placed in radial direction around the pipes that are to be welded together. Compared to the known line-up clamp that can be moved within the pipes and the aforementioned known welding device that works with clamping sleeves, the advantage is obtained that bringing the device to its destined place does not need much movement along the first pipe.

0024Preferably the frame is provided with, preferably hydraulic, operating means for moving the frame parts that can be opened.

0025In an advantageous manner the frame that is situated outside around the pipes can be used for an additional function, in that sense that the frame is furthermore provided with a wind shield for screening off the welding area radially to the outside.

0026Preferably the frame is furthermore provided with a longitudinal shell or structure extending in pipe centre line, which preferably has a circumference of 180 degrees or less. Said structure or said longitudinal shell can be advantageous for the aligning and for the movement of the frame, as well as for the support of the parts for the operation and drive of the parts of the device. It is advantageous here when the longitudinal shell or structure is provided with supporting or guidance rollers, which preferably in pipe centre line direction are in line with each other like several rollers.

0027The aligning and guidance is promoted when several sets of rollers are present which are spaced apart in circumferential direction.

0028Preferably the first and the second clamping means are arranged on different frame parts, that are connected to each other by means of connection means that can be adjusted in axial direction, preferably (hydraulic) cylinders, in order to be able to adjust the position of the end edges to the desired position for the weld.

0029From a further aspect the device comprises means for operating the first clamping means, means for determining an abutment position of the first clamping means, means for storing the abutment position in a memory, means for operating the second clamping means, in which the means for operating the second clamping means are connected to the control means for moving the second clamping means to a position corresponding to the abutment position, based on the abutment position as stored in the memory.

0030Preferably the means for operating the first clamping means and the means for operating the second clamping means are adapted for urging the clamping means from the abutment position to a clamping position.

0031The invention will be elucidated below on the basis of an exemplary embodiment shown in the attached drawing, in which: <ul id="ul0001" list-style="none"><li>Figure 1 shows a view in perspective on a device according to the invention, in a partly opened position;</li><li>Figure 2 shows an end view on the device of figure 1, in another position; and</li><li>Figure 3 shows a view in perspective on the device of figure 1, however from another side.</li></ul>

0032The aligning device 1 of the figures 1 and 2 is used for aligning the pipes 2 and 3, which are situated with their end edges near each other. The pipes 2 and 3 are here supported by means that are not further shown, the pipe 2 for instance on blocks or a mound of soil, the pipe 3 hanging from a crane or also on a mound of soil. The part of the pipe line that is ready extends in the direction A.

0033The device 1 comprises a frame 100. The frame is substantially formed by two rings 101 and 102, in which clamping shoes 32 and 33, respectively, have been arranged in a radially extendable and retractable manner, in which in figure 1 the ends of the radially movable jacks 30 and 31, respectively, of the clamping shoes 32 and 33, respectively, can be seen.

0034The main parts of the rings 101 and 102 are semi-circular brackets 9 and 10, which at their ends are hingedly connected to bracket segments 11, 12 and 41, 51 by means of hinged joints 25, 26 and 42 (see figure 2: it will be understood that the bracket 10 is designed substantially identical to bracket 9). The bracket segments 11, 12 and 41, 51 are moreover connected to the brackets 9 and 10 by means of hydraulic cylinder assemblies 13, 14, 15, 16, and namely by means of hinged attachments 19, 20, 43 on the brackets 9 and 10, hinged joints 21, 22 and 44 on bracket segments 11, 12 and 41, 51 and cylinders 23, 24 and 45 attached in between them. Bracket segment 51 corresponds to bracket segment 41.

0035As can be seen in figure 2 the clamping shoes 32, 33 form series running in circumferential direction.

0036The frame 100 is further provided with supports 17 and 18 extending radially and axially from the brackets 9 and 10, which supports are connected to each other by means of cylinders 52a, 52b in a rigid, though axially adjustable manner. In a comparable manner supports 36, 37 and 34 and 35, respectively, extend from the bracket segments 11, 12 and 41, 51, which supports are connected to each other by means of cylinders 39 and 38 in the same manner as the supports 17 and 18.

0037Furthermore attached to the frame is a relatively long, semi-circle cylindrical shell 4 to the already part of the pipe line (which shell is short enough, however, to be able to traverse the bends of the pipe line) and a relatively short funnel 5 extending around the pipe 3, which funnel for that matter is divided. The shell 4 can also be formed like an open structure, such as a lattice structure. The shell 4 can be provided with running/supporting wheels 6, 7 and 8, with which the device 1 is supported on the pipes 2 and 3 and can be moved over it in the direction B. In this case the wheels or rollers 6 and 8 can rotate freely, to which end, as shown for the rollers/wheels 6 and 8, suspensions 27 and 29 have been provided. The rollers 7 are driven by means of a drive supported on the shell 4, which drive is not shown, and are bearing mounted in trestles 27. An active control can be provided for the rollers 7. A roller can furthermore be coupled to an inclinometer. Finally the exemplary embodiment 1 shown, according to the invention is provided with a bracket 50 which is attached to both the shell 4 and the frame and connects them to each other, from which bracket the device can be suspended during its placement and removal and by means of which the device 1 can be pulled in the direction B. Apart from the bracket 50 no constructive connection is necessary between the shell 4 and the frame 100.

0038The bracket assemblies 9, 10, 11, 12, 41, 51 assembled in the manner of figure 1, form as it were one frame and are moreover able to offer room to welding means, such as a guide for a welding robot extending in circumferential direction, the welding robot itself (see 80 in figure 3), gas supply means, wire supply means etc. Moreover the frame or shell 4 can offer room to driving means for the cylinders 23, 24, 45 and so on and for the clamping shoes 32 and 33 that are provided on the brackets and the bracket segments.

0039Furthermore a control and regulation unit (not shown) has been arranged on the frame 100 or on the shell 4, with which unit the various parts can be operated and controlled. Said unit particularly comprises a measuring device for determining the position of the clamping shoes 32 and 33, in particular at abutment against the wall of the pipe concerned, and storing said position in the memory.

0040When the pipes 2 and 3 have to be welded to each other with their ends, the device 1 is lowered on the bracket 50, until the wheels or rollers 6, 7, 8 find support on the outer surfaces of the pipes 2 and 3. In this way the device 1 is also somewhat centred with respect to the pipe 2. The pipe 3 is then still hanging from a crane. Subsequently the cylinders 23, 24, 45 are activated to urge the bracket segments 11, 12, 41, 51, according to rotation movements C and D, from the opened position into the closed position, for bracket 11 shown in figure 2. Subsequently a tangential coupling is made with the help of couplings 53a, 53b between the supports 34 and 36 that are near each other, and the same for the other supports 35 and 37, so that an as it were continuous ring bracket is created. The funnel 5 here helps as orienting means for the pipe 3 hanging from the crane, which after that can be supported by placing a mound of soil under the pipe 3.

0041Subsequently the jacks 30 are operated to let the shoes 32 abut the outer surface of the pipe 2. Said position, which corresponds to the degree of radial expansion of the jacks in question, is noticed by the aforementioned measuring device, and on the basis thereof a contour sketch is made and stored in a memory. Subsequently the jacks 30 are driven to let the shoes 32 clamp the pipe 2.

0042The jacks 31 are then driven to bring the shoes 33 against the outer surface of the pipe 3 and subsequently move it to a position corresponding to the position as determined by the measuring device for the corresponding shoes 32, in order to obtain an identical contour sketch, by deforming the wall of the pipe 3 where necessary. When the contour of pipe 3 is already sufficiently of the same shape as pipe 2, adjustment of pipe 3 is of course unnecessary. The jacks 31 are subsequently driven to let the shoes 33 clamp the pipe 3 entirely, so that the pipes 2 and 3 are now both clamped and, as it were, form a unity with the frame 100 and as a result are fixed radially with respect to each other, in line with each other. It is noted that the jacks are adapted for generating sufficiently large clamping and deformation forces, such as for instance 3-4 tons.

0043Subsequently the hydraulic cylinders 38, 39, 52a and 52b are operated to bring the end edges of the pipes 2 and 3 at the wanted distance from each other for making the weld. In case of a V-seam a little distance is necessary, but in case of a J-seam not. When the wanted distance is reached the cylinders are fixed/secured in their expansion.

0044The aligning device 1 has been installed then and applying the welded joint can be started with with the help of welding robot 80, which is moved in the circumferential direction E. With the device according to the invention adjustment can take place with such precision that for welding also laser welding methods can be used.

0045It is advantageous when welding to weld the pipes 2 and 3 to each other such that they are connected to each other in a movement fixed manner, to move the device 1 to a next welded joint to be made and to simultaneously finish the weld between pipes 2 and 3 with other welding means.

0046When the pipe line in question is completed, the device 1 need not be moved to a location where it can be driven from the last pipe, but the bracket segments can simply be opened again and the device 1 can be hoisted away.