CA2019897C - Tightener - Google Patents

Abstract

The tightener comprises a scissor clamp having first and second arms pivotally connected at their upper ends. At their lower ends, the arms are pivotally connected with the ends of a loop of chain that encircles a pair of semi-circular steel shells encircling a pipeline. The rod of a cylinder is pivotally connected to move the front arm toward the rear arm. The cylinder is positioned to operate generally perpendicularly relative to the arms.

Description

~1989~

2 In my co-pending Canadian application 2 o o ~ 8 ~1 3 - filed December 6, 1989, I teach a sleeve assembly for 4 repairing a leak in the wall of a steel pipeline for conveying oil. This assembly involves mounting a pair of semi-circular 6 steel shells around the line and tightening or pressing them into 7 load-applying engagement with the circular pipe wall. One of the 8 shells carries a protruding annular seal member which seats in 9 a recess formed by the inner surface of the shell. The seal member surrounds the leaking aperture and seals around it to 11 prevent fluid escape between the shell and the pipe. Once the 12 seal member has sealed, the stressed shells are welded 13 longitudinally to create a permanent, full encirclement sleeve.
14 In connection with tightening the shells against the pipe it is desirable:
16 - That, as much as possible, the load being applied 17 by the tightener be distributed uniformly to the 18 shells. If the load is relatively concentrated 19 at a point, there is a risk of denting the sleeve and pipe;
21 - That the tightener used be adapted for use with 22 shells and pipe of different curvatures or 23 diameter; and 24 - That the tightener is powered by a fluid cylinder so that the extent of loading may conveniently be 26 monitored.

2 *

201~897 2 In accordance with the invention, there is provided:
3 - a scissor clamp having arms pivoted at a first end 4 and having means at the second end for engaging the two ends of a chain loop; and 6 - a fluid-actuated cylinder disposed substantially 7 perpendicularly to the arms when the latter are 8 together, said cylinder carrying a support plate 9 at one end, the rear surface of the clamp's first arm abutting the support plate, the cylinder being 11 connected to the clamp's second arm between its 12 ends, whereby the cylinder may bias the second arm 13 toward or away from the supported first arm.
14 Preferably the abutting portions of the first arm rear surface and the support plate front surface have a concave/convex 16 conformance, so that the first arm remains well supported as the 17 clamp arms pivot between open and closed positions with the chain 18 tensioned.
19 The chain can be lengthened or shortened to leave a gap between its ends, when the chain is taut, which gap is about 21 equal to the spacing between adjacent chain pins. As a result, 22 the radial loading applied against the shells and pipe by the 23 undersurface lobes of the chain is substantially uniformly 24 distributed about the circumference of the sleeve formed by the shells.

2 Figure 1 is a partly broken away side view of the 3 tightener, comprising a clamp, chain and cylinder, mounted on a 4 shell and pipe assembly with the chain in a tensioned state, some of the parts being shown in shadow lines;
6 Figure 2 is a simplified rear perspective view of the 7 tightener mounted on the shell and pipe assembly;
8 Figure 3 is a simplified side view showing the clamp 9 in operation; and Figure 4 is a front view of the front arm of the clamp, 11 showing the clevis, rod and arm pins, and the rod of the 12 cylinder.

14 The tightener 1 comprises a clamp 2 having a pair of jaws or arms 3,4 pivotally connected at their upper ends by a 16 pin 5. Each arm 3,4 is formed to provide a clevis 6 at its lower 17 end. The rod 7 of a fluid-actuated cylinder 8 extends through 18 the rear clevis 6 and is connected at its forward end by a pin 19 10 to the clevis 6 of the forward arm 3 between its ends. The cylinder 8 carries a support plate 11 at its forward end. The 21 rear surface 12 of the rear arm 4 of the clamp 2 abuts the 22 support plate 11.
23 The rear surface 12 of the rear arm is formed with a 24 convex portion 13 and the front surface 14 of the support plate 11 is formed with a concave portion 15 that conforms with the 26 portion 13. This "knuckle joint" arrangement permits the force 27 from the hydraulic cylinder to be distributed equally and 201~7 1 repeatedly to the clamp arms. This enables the clamp to be used 2 with pipe and shells of different diameters.
3 The cylinder 8 is disposed to act generally 4 perpendicularly relative to the arms 3,4.
At their lowest extremities, the arms 3,4 are each 6 connected by an end pin 16 with one end of a loop 17 of leaf 7 chain. When the loop 17 is just tensioned, the ends 18 of the 8 loop 17 are spaced apart a distance substantially the same as the 9 distance between the lobes 19 of the undersurface of the chain.
Thus the inwardly directed loading of the tightening chain is 11 substantially evenly distributed about the circumference of the 12 shells 20 which are mounted on the pipeline 21. Strips 22 of 13 Teflon* or the like are preferably provided between the shells 14 20 and the pipeline 21, to save the pipeline from scoring by the chain and to ease the advance of the chain as it is tightened.
16 A lift lug 22 is connected with the upper ends of the 17 arms 3,4 for handling the clamp 2.
18 A safety housing 23 encloses the arms 3,4 in case of 19 breakage.
Conventional means, such as a hand-operated pump (not 21 shown) will be connected with the cylinder 8 to actuate it.
22 The scope of the invention is set forth in the appended 23 claims.

-:- * designates a trade-mark

Claims (2)

1. In combination:
a pipeline;
a pair of semi-circular shells mounted about the pipeline; and a tightener for clamping the shells against the pipeline, said tightener comprising a scissor clamp having a pair of arms pivotally connected at their first ends, a loop of chain extending around the shells, the ends of the loop being pivotally connected with the second ends of the arms, whereby the arms may pull on the loop ends to tighten the loop about the shells, a fluid-actuated cylinder, pivotally connected with the first arm between its ends, for biasing the first arm toward or away from the second arm, said cylinder being arranged generally perpendicularly to the arms and being spaced out of contact with the chain, said second arm abutting and being supported by the front end of the cylinder.

2. The combination as set forth in claim 1 wherein:
the cylinder carries a support plate at its front end, the rear surface of the second arm abuts the front surface of the support plate, and the abutting portions of the second arm rear surface and the front surface of the support plate have mating curved surfaces.