TENDEUR

TIGHTENER

Abrégé anglais

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.

Revendications

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

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.

Description

~1989~
1 BACRGROUND OF THE INVENTION
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

1 SUMMARY OF THE INVENTION
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.

2019897
1 DESCRIPTION OF THE DRAWINGS
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.

13 DESCRIPTION OF THE PREFERRED EMBODIMENT
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

Dessin représentatif