APPARATUS FOR CLAMPING A PIPE OR TUBE

Abstract: By providing cooperating guide blocks (13) about halfway the lenght of the wedges (8) between the buttons (16), said blocks (13) comprising a projection (14) on the one side of the wedge and a recess (15) on the other side, it is sufficient to provide an apparatus for clamping heavy pipes or tubes with a low number of driving means (11), whereas at the same time mounting of the blocks (13) is very simple.

Description: The invention relates to an apparatus for clamping a pipe or tube, comprising a cylindrical sleeve onto which at the interior surface at regular angular distances a number of counter wedges with guide tracks has been arranged, over which guide tracks wedges comprising inwardly directed buttons can travel in the axial direction of the sleeve, which wedges can be driven by at least one means in order to move their buttons in radial direction up to the interior surface of the sleeve, while engaging means have been arranged to have the wedges move synchronously. Such an external pipe clamp for lifting relatively ligth drilling pipes with an outer diameter of up to 762 mm (30") is known from US-A-4,275,488. With this known apparatus, the engaging means have to be united before mounting them on the apparatus. This feature is inconvenient if an apparatus is concerned that is to be used to keep tubes with a diameter of e.g. 1829 mm (72") or even 2134 mm (84"), lifted to their position by a crane ship, firmly in place during welding. Known equipment for handling such heavy tubes have the joint disadvantage that under the influence of different actions of the driving means, the wedges will not always reciprocate synchronously. On account of that, these known apparatus have to be designed with greater dimensions than is strictly necessary. Apart from that, with the known apparatus the driving means of the wedges are easily damaged. The invention aims to improve the above-mentioned situation. According to the invention, this has been attained in that the engaging means consist of guide blocks arranged in the plane of operation of the wedges, said guide blocks having a projection at the one side of the wedge and a recess on the other side, the projections being adapted to reciprocate within the recesses as the wedges are moved in radial direction in relation to the interior surface of the sleeve. The guide blocks are preferably arranged in a recessed portion about halfway the length of the wedges between the buttons. Only a small number of driving means is required. In theory, even one driving means would suffice. Since the driving means have been arranged between two adjacent wedges, the additional advantage of a compact apparatus is obtained. In those places where no driving means have been applied, spacer pieces can be provided. In that case the projections and recesses of the guid blocks have been offset in the direction of the cylindrical sleeve so as to reciprocate in bays (8) of the spacer pieces (6). The invention will be further elucidated hereafter on the basis of the drawing, in which as an example an embodiment of an external clamping apparatus according to the invention is represented. In the drawing: fig. 1 shows a top view of the apparatus, fig. 2 shows, at a larger scale, a cross-section along the line II-II of fig. 1 with the wedges in two extreme positions, fig. 3 shows, at a larger scale, a cross-section along the line III-III of fig. 1, and fig. 4 shows a downcast view of the interior surface of the apparatus of fig. 1. The clamping apparatus shown in figures 1-4 comprises a cylindrical sleeve 1 which at its top and bottom is provided with external reinforcing flanges 2 and 3. On the interior surface of the sleeve 1 a set of twenty counter wedges 4 with guide tracks 5 has been arranged at regular mutal angular distances. A set of ten spacer means 6 has also been arranged at regular mutual angular distance, always between two counter wedges 4 and these spacer means extend over the entire height of the sleeve 1. The radially inwardly directed sides of the spacer means 6 are provided with slabs 17 for covering a bay 18 in which the guide blocks, which have been deleted from figure 3 but are to be described hereafter, move. The slabs 17 are both at the top and at the bottom provided with a bevel 7 for guiding a pipe or tube (not shown). The guide tracks 5 of the counter wedges 4 cooperate with wedges 8, only five of which have been shown in fig. 1. Supposing that the shown apparatus has been designed for handling tubes with a diameter of 2134 mm (84"), then it can be adapted for handling tubes of 1829 mm (72") diameter by positioning filler pieces (not shown) between the sleeve 1 and the counter wedges 4. It appears from figure 2, that the wedges 8 comprise two guiding arms 9 that engage around the guide track 5. The top guide arm 9 of a number, e.g. two or four wedges 8, is rotatably connected to the end of a piston rod 10 of a cylinder 11 that is rotably connected itself to a counter wedge 4. About halfway the length of the wedges 8 in a recessed portion between the buttons 16 a guide block 13 is fastened with the aid of a set of four bolts 12, said guide block having on the one side of the wedge 8 a projection 14 and on the other side a recess 15. Said projections 14 and recesses 15 obviously have to be able to pass the bays 18 of the spacer means 6. For reasons of standardization, it is of course efficient to construct all the guide blocks 13 with S-shaped ends in top view. When the piston rod 10 is moved from the high position indicated by broken lines to the low position indicated by full lines, all the wedges 8 end up on a smaller diameter as the guide blocks 13 take on the non-driven wedges 8. Moreover the possible disharmonious action of the cylinders 11 is thus compensated for. The wedges 8 have been provided in the usual manner with buttons 16 for a tight clamp into the exterior surface of the tube or pipe. At first sight, it would seem a major disadvantage with respect to the known apparatus that the button series are interrupted. However, this is only partly so, as for calculating the maximum admissable load of the tube or pipe its length is obviously most relevant, although the addition dependent on the diameter and wall thickness past the ends is also taken into account. This may also be done at the location of the guide blocks 13. The scope of the claims also cover other embodiments than the one shown in the drawing.

Claims: 1. Apparatus for clamping a pipe or tube, comprising a cylindrical sleeve (1) onto which at the interior surface at regular angular distances a number of counter wedges (4) with guide tracks (5) has been arranged, over which guide tracks wedges (8) comprising inwardly directed buttons (16) can travel in the axial direction of the sleeve (1), which wedges (8) can be driven by at least one driving means (11) in order to move their buttons (16) in radial direction up to the interior surface of the sleeve (1), while engaging means (13) have been arranged to have the wedges (8) move synchronously, characterized in that the engaging means consist of guide blocks (13) arranged in the plane of operation of the wedges (8), said guide blocks having a projection (14) on the one side of the wedge (8) and a recess (15) on the other side, the projections (14) being adapted to reciprocate within the recesses (15) as the wedges (8) are moved in radial direction in relation to the interior surface of the sleeve (1). 2. Apparatus according to claim 1, characterized in that the guide blocks (13) are arranged about halfway the length of the wedges (8) between the buttons (16). 3. Apparatus according to claim 1 or 2, characterized in that the number of driving means (11) is considerably lower than that of the wedges (8) and counter wedges (4). 4. Apparatus according to one of claims 1-3, characterized in that in places where no driving means have been applied, spacer pieces (6) are provided. 5. Apparatus according to claim 4, characterized in that the projections (14) and recesses (13) of the guide blocks (13) have been offset in the direction of the cylindrical sleeve (1) so as to reciprocate in bays (18) of the spacer pieces (6). 6. Apparatus according to any of the preceding claims, characterized in that the driver means are fluid-operated cylinders (11).

Inventors: VAN STEIJN, THEODORUS GERARDUS WILHELMUS
Applicants: P. BOER & ZN. B.V.
Application year: 1989
Main classification: B23K37
IPC codes: B23K37