Apparatus for clamping pipe or tube

An apparatus including wedges with buttons and cooperating guide blocks positioned about halfway along the length of the wedges between the buttons, each block including a projection on one side of the wedge and a recess on the other side, for clamping heavy pipes or tubes with a low number of driving assemblies. The blocks are mounted in a very simple manner.

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 
have been arranged, over which guide tracks wedges comprising inwardly 
directed buttons can travel in the axial direction of the sleeve. The 
wedges can be driven by at least one means in order to move their buttons 
in a radial direction up to the interior surface of the sleeve, while 
engaging means have been arranged to have the wedges move synchronously. 
An external pipe clamp for lifting relatively light drilling pipes with an 
outer diameter of up to 30" is known from U.S. Pat. No. 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 this type of 
apparatus is used to lift and hold tubes with a diameter of e.g. 72" or 
even 84", 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, this type of conventional 
apparatus has 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 a radial direction in relation to the 
interior surface of the sleeve. 
The guide blocks are preferably arranged in a recessed portion about 
halfway along 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 guide blocks have been offset in the direction of the 
cylindrical sleeve so as to reciprocate in bays (8) of the spacer pieces 
(6).

The clamping apparatus shown in FIGS. 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 mutual angular distances. 
A set of ten spacer means 6 has also been arranged at regular mutual 
angular distances, 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 
FIG. 3 but are to be described hereafter, move. The slabs 17 are provided 
both at the top and at the bottom 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 84", 
then it can be adapted for handling tubes of 72" diameter by positioning 
filler pieces (not shown) between the sleeve 1 and the counter wedges 4. 
It appears from FIG. 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, of the 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 along 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 dependence 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 drawings.