Seal and clamp assembly for pipeline flanged connection

The assembly is designed to contain a leak arising from a damaged gasket positioned between the flanges of a pipe connection forming part of a pipeline carrying pressurized fluid. The assembly comprises a pair of steel half rings that are hinged together at one end so that they can be mounted to the connection in the form of a split ring. Each half ring contains an elongate seal element having an annular configuration. The ends of the half rings are lapped so that the split ring can be contracted with the ring ends overlapping. A chain and clamp assembly is tightened around the split ring to compress the seal elements into sealing engagement with the flanges. Shoulders formed by the half rings squeeze the abutting seal element ends together to effect a seal at the split ring breaks.

FIELD OF THE INVENTION 
This invention relates to a seal and clamp assembly for sealing a flanged 
connection whose gasket is leaking. 
BACKGROUND OF THE INVENTION 
The present invention was developed to temporarily seal a flanged 
connection joining two pipe ends. The flanged connection forms part of a 
pipeline carrying fluid under pressure, such as natural gas or oil. 
There are many such connections along the length of a pipeline and it is 
not uncommon for the gasket of one of them to fail and begin leaking. 
Heretofore, the normal practice for repairing such a leak has first of all 
involved isolating the segment of line containing the connection. This 
would be done by closing upstream and downstream valves at each end of the 
segment. Then the connection would be dismantled and the gasket would be 
replaced. 
This repair procedure requires that the flow of fluid through the line must 
be temporarily suspended. This is an undesirable requirement. 
It would be advantageous if the leaking connection could be temporarily 
externally sealed and contained with a suitable, easily applied assembly. 
Replacement of the gasket could then be postponed to a more convenient 
time, such as that of a scheduled maintenance shut-down of the pipeline. 
The present invention is directed to providing such an assembly. 
The new assembly incorporates some features of a known pipeline repair 
sleeve assembly. This known assembly was designed for repairing a small 
hole in the pipe wall. The assembly was disclosed in U.S. Pat. No. 
5,123,451, issued to Donald Savard. 
The Savard assembly comprises a pair of semi-circular steel shells. The 
inner surface of one shell forms a central, circular recess. A flat, 
cylindrical, annular seal element is seated in the recess. It closely fits 
the recess, so that it is supported and contained along its top and side 
surfaces by the recess walls. The seal element protrudes inwardly a small 
amount beyond the inner surface of the shell containing it. When used, the 
shell carrying the seal element is mounted to the pipe so that the seal 
element encircles the leakage site. The other shell is also applied to the 
pipe. The resulting split sleeve almost entirely encircles the pipe. A 
belt-like chain and clamp assembly is then positioned around the shells 
and cinched up to tightly clamp them to the pipe to create steel-on-steel 
contact. The ends slide together during clamping. These ends are then 
welded together longitudinally and the sleeve ends are welded 
circumferentially to form a permanent pressure vessel encapsulating the 
leaking pipe segment. The chain and clamp assembly is then removed. 
When the sleeve has been formed in this manner, the protruding seal element 
is compressed into sealing engagement with the pipe surface. The 
pipeline's internal pressure acts against the radial inner surface of the 
seal element opening and further compresses the seal element into sealing 
engagement with the rigid containing surfaces of the shell and pipe. As 
the seal element is flat, broad and thick, its considerable volume cannot 
be easily extruded through any slight clearance between the shell and 
pipe. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, a seal and clamp assembly is 
provided for temporarily sealing and containing a flanged connection whose 
gasket is leaking. The assembly involves the following: 
A pair of rigid half rings are provided having means for connecting them 
together at their ends to form a split ring having two breaks; 
Each half ring has lapped ends. At one end, the inner portion of the half 
ring wall is cut back to form an inner recess and an outer protruding 
segment. At the other end, the outer portion of the half ring wall is cut 
back to form an outer recess and an inner protruding segment. When the two 
half rings are assembled, the inner recess of one half ring receives or is 
associated with the inner protruding segment of the other half ring. The 
shoulder end face at the inner end of the inner recess of one half ring 
and the end face of the inner protruding segment of the other half ring, 
provide radial squeezing surfaces at each break for a purpose to be 
described; 
The inner surface of each half ring forms an inwardly opening, central 
channel, of rectangular cross-section, extending longitudinally thereof; 
A pair of flexible and resilient seal elements are provided, one for each 
ring half. Each seal element takes the form of an annular, flat, elongate 
rectangle, having a central rectangular opening. Stated otherwise, the 
seal element incorporates a pair of coextensive, parallel, spaced apart 
side members and a pair of transverse end members. One of the end members 
extends outwardly beyond the side members, to form protruding lugs. This 
end of the seal element can be described as having a double T-like shape 
(i.e. "TT"); 
A seal element is seated in the channel of each half ring. The double 
T-like end seats in and fills the inner recess of the half ring. The top 
and outer radial surfaces of the seal element have a close fit with the 
channel, so as to be supported and contained by the channel walls. The 
inner radial surfaces of the seal element are open to the pressure 
originating from the leak. The seal element is thicker than the channel is 
deep and protrudes inwardly therefrom; 
Preferably a hinge assembly is provided for connecting and hinging one pair 
of half ring ends, said assembly being constructed so as to enable the 
ring to contract a limited amount; and 
Preferably a latch assembly is provided for connecting the other pair of 
half ring ends, said latch assembly being adapted to complete securing the 
hinged half rings together. 
In use, each half ring is fitted with a seal element which is seated in the 
channel. The hinged together half rings are then mounted to the opposed 
flanges of the connection. The openings in the seal elements are 
positioned directly over the leaking gasket. The side members of the seal 
elements engage the surfaces of the two flanges. The latch assembly is 
engaged to form a loose split ring. A belt-like chain is positioned about 
the half rings and is cinched tight with a cinching or clamp device. As a 
result, the side members are pressed inwardly to seal against the flanges. 
As a further result, the inner radial squeeze circumferential surfaces of 
the half ring ends, at each break, cooperate, as the lapped ends slide 
together in overlapping fashion, to squeeze together the seal element's 
lug ends to effect a seal at the breaks. Pressure from the leak acts 
against the inner radial surfaces of the seal elements, to deform the side 
members so that they press harder against the flange circumferential 
surfaces. 
The belt-like chain can be locked in place and the cinched-up seal and 
clamp assembly can be left in place until the gasket is to be replaced. 
The assembly can then be quickly removed. 
The seal and clamp assembly is characterized by the following features: 
The use of a split ring enables a quickly mounted, properly conforming 
rigid jacket to be used. However, the split ring has to be adequately 
sealed at the breaks to contain the internal pressure of the pipeline 
fluid. The provision of the double-T end of the seal element, in 
conjunction with the squeeze surfaces of the lapped ends of the half 
rings, enables this objective to be met; 
The protruding nature of the seal elements, in conjunction with the 
overlapping, adjustable nature of the half ring ends, enables the seal and 
clamp assembly to fit itself to the flanges in sealing engagement, even 
though the flanges may be misaligned; and 
The pressure of leaking fluid acts against the inner radial surfaces of the 
seal element's central opening only serves to cause the element to seal 
better.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The present invention relates to a seal and clamp assembly 1. The assembly 
is used to temporarily enclose and seal the leaking gasket 2 of a flanged 
connection 3. 
The flanged connection 3 connects a pair of pipe ends 4 and forms part of a 
pipeline system carrying fluid under pressure. 
The assembly 1 comprises a pair of rigid half rings 5,6. These half rings 
are hinged together at one pair of ends 7,8 and can be fastened together 
at the other pair of ends 9, 10 to form a split ring 100 which closely 
encircles the flanges 11, 12 of the connection 3. 
Each half ring is semi-circular in configuration. At one end, the outer 
portion 14 of each half ring is cut back to form an outer recess 15 and an 
inner protruding segment 16. At its other end, the inner portion 17 of the 
half ring is cut back to form an inner recess 18 and an outer protruding 
segment 19. The inner recess 18 is bounded at its end by a transverse 
shoulder 20 having a radial end face 21. The inner protruding segment 16 
has a radial end face 22. 
The half rings 5,6 are assembled together so that each pair of associated 
half ring ends 7,8 and 9,10 has one end with an inner recess 18 and the 
other end with an outer recess 15. Thus, for each associated pair of ends, 
the protruding segments 16, 19 overlap in sliding engagement. 
The internal surface 23 of each half ring is formed to provide an internal 
channel 24 which extends centrally and longitudinally thereof. The channel 
24 has a rectangular cross-section bounded by laterally spaced apart side 
walls 102. 
A pair of resilient, flexible seal elements 25 are provided, one to be used 
with each ring half. 
Each seal element 25 comprises a pair of parallel, spaced apart, 
coextensive side members 26 joined at their ends by transverse end members 
27, 28. The seal element 25 therefore has an annular form and defines a 
central opening 54. One end member 27 extends laterally beyond the side 
members 26 to form protruding lugs 29. This end of the seal element can be 
described as having a "double T" shape. 
Each seal element 25 is dimensioned to extend the full length of the half 
ring with which it is associated. It snugly fits in the channel 24 so that 
its outer surface 57 and side surfaces are supported and contained by the 
solid surfaces of the channel. The seal element 25 is of sufficient 
thickness so that its inner surface 56 protrudes inwardly from the shell's 
internal surface 23. 
The transverse end member 27 of each seal element 25 is disposed in the 
inner recess 18 of its associated half ring. Thus, when the two half rings 
5,6 are assembled, each transverse end member 27 is bracketed by the 
recess radial end face 21 of one half ring and the protruding segment 
radial end face 22 of the other half ring. 
A hinge assembly 30 is provided for hinging and connecting the two half 
rings 5,6 together at one pair of ends 7,8. More particularly, a pair of 
laterally spaced apart bosses 31 protrude radially from the outer surface 
of one ring half. A pair of laterally spaced apart bosses 32 protrude 
radially from the side surfaces of the other ring half and bracket the 
bosses 31. The bosses 32 each form a slot 33 extending longitudinally 
along the main plane of the split ring 100. Each boss 31 carries a 
laterally extending pin 34 which slides in the adjacent slot 33. The hinge 
assembly 30 thus enables the two lapped ring halves 5,6 to move together 
to contract the split ring 100 a limited amount, while still remaining 
operative to hinge and connect them together. 
A latch assembly 40 is provided for fastening the ring half ends 9, 10 
together, once the ring halves have been mounted onto the flanges. The 
latch assembly 40 comprises a pair of bosses 41 protruding radially from 
the side surfaces of one half ring end 9 and supporting a laterally 
extending pin 42 on which a bolt and nut assembly 43 is pivotally mounted. 
A second pair of bosses 44 protrude radially from the side surfaces of the 
other associated half ring end 10. The bolt and nut assemblies engage the 
bosses 41, 44 to secure the ends 9, 10 together. 
Retainer tabs 50, 51 are spaced angularly and protrude radially from the 
side surfaces of the half rings 5,6 for roughly guiding the half rings 
into proper position over the outer surfaces 52 of the flanges 3. 
In use, the seal elements 25 are seated in the channels 24 of the two 
hinged ring halves 5,6. The split ring 100 is mounted to the flanges 11, 
12 so as to extend therearound, with the inner surface 56 of one side 
member 26 of each seal element riding on circumferential face or outer 
surface 52 of one of the flanges, as shown in FIG. 10. The seal elements' 
central openings 54 are then positioned over the leaking gasket 2 to form 
a sealed chamber 55. 
A belt-like chain and clamp assembly 60 is now provided. The assembly 60 is 
similar to that described in U.S. Pat. No. 5,123,451. In general it 
comprises a belt-like chain 61 and a clamp device 62. The clamp device 62 
has jaws 63,64 which pivot about a pin 68 at their outer ends and attach 
to the chain's end links 84,86 at their inner ends 80,82. A hydraulic 
cylinder 70 is mounted to a stationary plate 72, which holds the back 
surface 76 of the jaw 63. The cylinder 70 pushes against a movable plate 
74, which bears against the back surface 78 of the jaw 64 and which is 
slidably connected with the stationary plate 72. The cylinder 70 thus 
biases the jaw 64 toward the jaw 63, thereby cinching the chain 61 tight 
and contracting the split ring 100. The ends of the chain 61 are then 
secured together by a bolt 87 and nut 89 connecting bosses 83,85 mounted 
to the chain ends. See FIG. 5. 
As the ring halves 5,6 are pressed to the pipe connection, the following 
results follow: 
the slot 33 and pin 34 of the hinge assembly 30 allow the ring half ends 7, 
8 to telescope a small amount; 
the two pairs of ring half ends 7,8 and 9,10 telescope to allow the split 
ring 100 to contract a small amount; 
the inner surfaces 56 of the seal elements 25 are pressed against the outer 
surfaces 52 of the flanges 11,12 and the outer surfaces 57 of the seal 
elements are pressed against the internal surfaces of the channel 24 to 
effect a circumferential seal; 
the leaking gasket 2 communicates with the sealed chamber 55; 
the overlapping half ring ends contract, squeezing the transverse end 
members 27,28 together to effect a seal at the end faces 58,59 of the 
abutting seal elements; the opposing pairs of radial faces 21,22 squeeze 
the transverse end member 27 projecting lugs 29 to effect a seal at the 
half ring breaks 7,8 and 9,10; and 
the leakage pressure acts against the inside radial surfaces 61 of the seal 
elements to intensify their compression and increase their sealing.