AU2001100465A4 - Chain type pipe alignment clamp - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION INNOVATION PATENT CHAIN TYPE PIPE ALIGNMENT CLAMP The following statement is a full description of this invention, including the best method of performing it known to me PIPE CHAIN CLAMP Field of the Invention The present invention relates to clamping devices used to assist in the fitting of pipe sections together, but is also relevant to many situations where two or more items need to be connected or held with clamping force.

Description of the Invention In a typical example, a chemical processing plant is constructed incorporating numerous pipelines which are connected together to transfer fluids between different locations. The pipes used for such purposes often need to be of considerable length and incorporate bends and various types of junctions. Often the piping layout is varied and includes many elbows, tees, reducers, weld neck flanges, etc.

For ease of manufacturer pipelines are constructed by joining standard or cut lengths of pipe together. Bends or junction fittings are similarly joined to pipe lengths as required.

Typically the joining process consists of accurately aligning the end of each pipe or fitting at a joint and then butt welding them together. Large diameters of pipe and varying configurations for assembly often present difficulties in achieving accurate alignment of their ends to be joined.

Various devices have been devised to assist in the process of aligning mating ends and holding them so that they may be tack welded prior to applying a full butt weld to the joint.

Some varieties of these devices are based on the principle of applying tension to a chain or chains around the circumference of one pipe at the location of the joint. Jacking screws linked to the chain or chains are then used to provide fine adjustment of the adjacent of pipe or fitting.

Most of the chain type devices use transmission roller type chain or similar. Some types of these devices are able to tension both ends of the active chain equally, but require a relatively open linked chain to achieve 3s attachment of the tension device. Consequently the size and or length of chain along with the size of the tension device varies depending on the diametrical size and weight range of pipe on which is to be used.

Other chain styles devices use transmission roller chain to improve the performance of the chain and thereby reduce the number of models needed to cover the range of pipe diameters. In operation the tension device is placed on the pipe and the attached chain wrapped around the pipe and s reconnected to the tension unit. The tension action generally acts directly on one end of the chain. Friction within the device and its action against the pipe can result in variation in the tension around the chain. This can cause such problems as slippage, skewing of the clamp or misalignment and a reduced ability to achieve the desired clamp tension.

It is the object of this invention to overcome, or at least ameliorate one or more of the deficiencies of these devices and/or improve function and performance. This includes the ability to use increased applied force and therefore improved clamping strength whilst keeping the weight of the device to a minimum. This results in a more compact and user friendly pipe clamp.

Summary of Invention According to an aspect of the present invention there is a pipe chain clamp apparatus having: a chain tension unit consisting of a base, an upper body, a screw action tension shaft and combined chain adjustment mechanism and locking devices, a chain (or tension band) preferably made from (though not restricted to) roller (transmission) or leaf (lifting) chain, jacking bars and jacking screws.

The invention's ability to use leaf chain for the tension band considerably improves the performance allowing greatly increased clamping forces to be applied by the device. (Leaf chain being stronger than roller chain of the same pitch and dimension.) In operation the chain is fed into the chain tension unit past one combined chain adjustment and locking mechanism. The chain is then wrapped 3s around the circumference of a pipe end and fed back past the chain tension unit and retained by a chain adjustment and locking mechanism on the other side The chain is drawn through the tension unit until most slack is removed from the chain. During this process jacking bars are placed at predetermined intervals along the chain. The clamp is so positioned that the jacking screws overhang the pipe end.

Activating the screw action tension device applies tension to both ends of the chain, thereby securely clamping the jacking bars against the periphery of the pipe end. The pipe to be joined is then abutted to the end of the first pipe and the jacking screws are then adjusted and tightened until the pipes are accurately aligned and secured.

Upon completion of tack welding of the joint, the tension is released on the chain and one or both ends of the chain may be disengaged from tension unit via the locking-adjustment mechanism so that the device can be moved to the next joint.

Brief Description of the Drawings Fig. 1 is a perspective view from above of the clamp located on 1is the end of a pipe according to a first embodiment of the present invention; Fig. 2 is a perspective view from below of the clamp located on the end of a pipe according to a first embodiment of the present invention; Fig. 3 is a perspective view from above of the clamp with both pipes located in preparation for tack welding according to a first embodiment of the present invention; Fig. 4a is a side view of the tension apparatus with both combined chain adjustment and locking mechanisms engaged; Fig.4b is a side view of the tension apparatus with one combined chain adjustment and locking mechanism disengaged; Fig.5a is a side view of the Pipe chain clamp apparatus located on the end of a pipe prior to tension being applied to the chain; is a side view of the Pipe chain clamp apparatus located on the end of a pipe after to tension being applied to the chain; Fig. 6 is an exploded view of the tension apparatus according to a first embodiment of the present invention; Fig 7 is a perspective view of the tension apparatus according to a first embodiment of the present invention; Fig 8 is a perspective view of the tension apparatus according to a second embodiment of the present invention; Fig. 9a is a side view of the jacking bar Fig. 9b is a top view of the jacking bar Fig. 9c is a perspective view of the jacking bar Fig. 10 is a side view of the tension apparatus according to a third embodiment of the present invention Detailed Description Referring to Fig. 1 and Fig. 2 there is illustrated a first embodiment of the pipe chain vice designated generally by the numeral 10. The apparatus includes a chain tension unit 11, a chain 12, jacking bars 13 and jacking screws 14. The chain tension unit includes a base 20, an upper body 21, tension shaft 22 and a combined adjustment and locking mechanism 23.

These figures show the pipe chain clamp secured in position at the end of a pipe where a joint is to be made. The chain 12 has been fed into the tension unit 11, jacking bars 13 added at desired intervals and then fed back into the other side of the tension unit and applied with tension.

Figure 3 shows the second pipe 16 placed in position and aligned to pipe 15 with jacking screws 14 ready for welding.

Fig. 4a shows how chain 12 feeds through passages 30a and in base 20 and passages 31a and 31b in upper body 21. The chain is locked in position both sides of the upper body 21 by spring loaded pawls 32a and 32b, acting in combination with the adjacent vertical walls of the upper body 21, against the chain link waists 33a and 33b respectively which in turn engage lobes 34a and 34b on upper body passage walls.

When the combination locking and adjustment mechanism 23b is disengaged as shown in figure 4b, the chain 12 is released and is able to be fed back and forth through passages 31b and 30b as required. This procedure can be carried out with the either or both locking or engagement mechanisms 23a 3s and 23b to allow insertion or removal of chain ends or adjustment of the chain length.

Significant advantages arise from using the paired of locking/adjustment system. The chain can be adjusted from either end. The chain 12 may be of any desired length and be long enough to cater for multiple sizes of pipe, without interfering with the performance of the clamp. In practice this would allow the welder to have a single chain length to cater for the most commonly used sizes. The mechanism's configuration is such that roller chain or leaf chain may be alternated through the device with out effect to the locking or adjustment function.

Tension shaft 22 has a threaded end 35 which engages with a corresponding thread in upper body 21 and a shoulder 36 which bears against surface 37 of base. The reduced end 37 of tension shaft 22 is free to rotate within hole 38 and retains base 20 with collar or retaining means 39.

The chain may have attachments 40 and 41 at respective ends of chain 12 to assist in retaining or feeding it through passages within tension unit 11 Fig. 5a shows the pipe clamp 10 located on the end of pipe prior the process of applying tension to the chain. As shaft 22 is rotated, upper body 21 moves away from base 20. (Fig. 5b) As both ends of chain 12 are securely locked to upper body 21 by locking mechanism 23, the chain is drawn up through passages 30a and 30b until it bears against the walls of these passages. Any remaining slack is thereby removed from the chain and a tensional force is consequently applied to the chain.

This process draws both ends of the chain up evenly and thereby applies an equal tension force to each end of the chain. As frictional forces can be considerable, this process therefore more equally distributes tensional forces throughout the chain and jacking bars thereby maximise the clamp force performance.

Existing clamps in effect try to "stretch" the chain around the pipe from one end only and the resulting frictional forces can be significant causing 3s misalignment or slippage particularly if there are any small irregularities in the pipe. This can significantly reduce clamping efficiency.

A handle 42 assists in turning shaft 22 by hand is shown in Fig. 7 A second embodiment of the present invention would be to have shaped head tension shaft to allow it to be turned with a longer armed tool to allow greater tension to be applied to the chain. The shape of the head would correspond to the tool to be used. Fig. 8 shows an example of such a shaped tension shaft 50 with a hexagonal head, which would allow it to be turned with a spanner.

Fig. 9a, Fig. 9b and Fig. 9c show various views of the Jacking bar 14. Chain 12 is fed through passage 18 in these bars. Locking screw 17 allows these jacking bars to set at desired locations along the chain 12.

An example of an alternative method of achieving the chain locking and adjustment mechanism is shown in Fig. 10. Upper body 51 has spring-loaded pawls 52 and 53, which pivot about axis 54. Spring 55 applies force to pawls 52 and 53 to assist in engagement with link waist of chain 12 and upper body vertical faces 56 and 57 respectively so as to achieve locking of the chain against lobes within the upper body 51.

Thus this locking system operates in a similar fashion to that described earlier.

Claims (4)

1. This is a versatile chain type pipe alignment clamp with new combined features that provide greatly enhanced performance over existing similar devices.

2. The unique chain tension configuration provides increased torsional forces as it acts equally on both ends of the chain thereby providing significantly improved clamping. Evenly distributed tensional forces throughout the chain also provide improved alignment performance. The clamps unique configuration ensures that the clamp exerts equal forces on both ends of the chain as it is activated thereby considerably reducing the frictional losses throughout the chain, jacking bars and chain tension unit.

3. The clamp's ability to accept leaf chain as well as roller chain gives it both versatility and strength to allow it to be used with both light and heavy wall pipe.

4. The clamp's combined adjustment and locking mechanism is provided at both ends of the chain provides for a simple means of adjusting, connecting and releasing the chain. This allows for ease of adjustment, an easy means of centralising the chain when using on a variety of pipe sizes or changing chains if using a different number of chains with preset jacking bars. The locking configuration for the chain is such that the clamping forces on retention of the chain increase in proportion to the force applied to the chain tension. Richard Dower 26 September 2001