Pipeline plug

A pipeline plug is disclosed having an elastomeric disc-shaped sealing element provided with deforming means whereby the outside diameter of the elastomeric element is deformed to reduce its outside diameter to facilitate its insertion onto a pipeline. In another embodiment described, the plugging element and the deforming means are so arranged that when the deforming means act on the element, the latter is expanded into a sealing arrangement. The plugging elements are shown at one end of a spool assembly with resilient guide means to permit movement of the plug through a pipeline, but the plugging elements and their deforming means can also be used separately.

FIELD OF INVENTION 
The present invention relates to a plug for temporarily sealing (plugging) 
open end of a pipe or vessel to prevent vapors, fumes or the like from the 
pipeline to migrate into a work area. 
BACKGROUND OF THE INVENTION 
Pipeline pigs are known to provide sealing of a portion of a pipeline when 
repairs, inspection or the like tasks are to be carried out. The known 
pigs are designed for use in an environment where relatively high 
pressures are involved. Therefore, they are of a robust, complex and thus 
expensive structure for use such as preventing vapors or the like to 
escape from a pipeline into a working area, where relatively low pressures 
are normally encountered. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a structurally simple 
plug particularly suitable for use at an end of a pipeline or vessel to 
shield a working area from vapours, fumes or the like present in a 
pipeline. 
In general terms, the invention provides a pipeline plug for temporarily 
plugging an end of a pipeline, vessel or the like, comprising an 
elastomeric, generally disc-shaped sealing element having a predetermined 
outside diameter at an outer periphery thereof. The plug further comprises 
actuation means for exerting pressure upon said element to change said 
predetermined outside diameter thereof.

DETAILED DESCRIPTION 
The preferred embodiment of the plug of the present invention is shown in 
FIG. 1. It can be inserted into an open end of a pipeline or vessel. 
Turning now to FIG. 1, the plug of the invention consist of a 
frustoconical, cup-shaped elastomeric sealing element 1. The element 1 has 
a central portion and a generally frustoconical segment diverging from the 
central portion presenting obliquely oriented major wall surfaces and a 
margin at the outboard ends of the wall surfaces, thereby presenting a 
concave axial face 1a and a convex axial face 1b. The concave face 1a is 
turned toward the pressurized part of the pipe P, the convex face 1b to 
the non-pressurized part of the pipe 1. The outermost part 2 of the 
element 1 defines the outside diameter of the element 1. It has the form 
of a cone and is furnished with radial ribs 3. The central portion 
presents a smaller inner diameter portion. 
The surface angle 4 of the outermost part 2 is so oriented that upon 
contact of the seal 1 with the pipe P the outermost part is generally 
aligned with the interior of the pipeline to allow the elastomeric sealing 
element 1 to come in full contact with the inside wall of the pipe P. The 
ribs 3 enhance the sealing capability of the element as each rib acts as 
independent seal. The sealing element is disposed between two flanges 5 & 
6 and fastened by bolts 7. The rear flange has thread 8 tapped at the 
centre to receive a jack bolt 9 used to move a deflector ring 10 forth or 
back forcing the sealing element 1 into a contracted state of FIG. 1, or 
releasing it thus permitting it to expand into contact with the pipe 1 as 
shown in FIG. 2. The jack bolt 9 is inserted through a clearance hole 11 
at centre of the radial plate 1 2 of the deflector ring 10. 
The friction between the bolt head 13 and ring plate 12 is reduced by a 
thrust ball bearing 14. The bolt 9 is axially secured to the plate 1 2 by 
a snap ring 15. 
The unit just described can be used by itself or in combination with two 
spools 16 equipped with resilient discs 17 or cups if the apparatus has to 
be transported through pipeline. 
In operation, the plug in the state of FIG. 1 is inserted in a pipeline to 
prevent leakage of gases or fumes from the pipe 9. In this stage the bolt 
9 or other actuation means for exerting pressure on the sealing element 1 
is active to axially displace the deflector ring 10 to the left as shown 
in FIG. 1 to deform the seal 1 into the contracted state. 
When the seal is placed at the desired location in the pipe P, the bolt 9 
or an equivalent actuation means is caused to move the ring 10 to the 
right of FIG. 1, to the position of FIG. 2, where the ring 10 no longer 
exerts axial pressure unto the seal element 1. The seal element expands by 
its own resiliency bringing the outermost part 2 and thus the ribs 3 into 
contact with the wall of the pipe P. At this expanded state, the sealing 
element 1 is active and provides a sealing barrier preventing escape of 
gases or the like from the pipe P. 
Those skilled in the art will readily appreciate that the described 
arrangement utilizing the bolt 9 and the threaded hole 8 may be 
substituted by other known mechanisms, for instance, by a hydraulic or 
pneumatic mechanism selectively exerting or releasing axial pressure at 
the plate 12. 
The second embodiment of the plug is shown in FIGS. 3 and 4. As in the 
first embodiment, it includes a frusto-conical cup-shaped elastomeric 
sealing element 101 having the general shape of a cone where the outside 
part 102 of the element is thickened and the outer surface thereof is 
furnished with radial ribs 103 to enhance effectiveness of the sealing 
element 101. In a relaxed state, the element 101 assumes the position of 
FIG. 3 where the seal is disengaged from the pipe wall 109. 
The centre of the sealing element 101 has a clearance hole 104 allowing a 
jack screw 105 to pass through, The inner surface of the element is 
supported by a deflection disc 106. The deflection disc has threaded hole 
107 at the centre for the jack screw 105 which also cooperates with an 
outer disc 108 to squeeze the sealing element 101 by pushing the 
deflection disc 106 and the outer disc 108 axially to each other. This 
action causes the element 101 to expand (FIG. 4) and the ribbed outer 
surface 103 is forced against pipe wall 109. Friction between the bolt 
head 110 and the back plate 8 is reduced by a thrust ball bearing 111. The 
lack screw 105 is axially secured in position relative to the disc 108 by 
a snap ring 112. 
The operation is similar to that of the first embodiment but in the 
embodiment of FIGS. 3 and 4 the sealing element 101 Is contracted when in 
relaxed state (FIG. 3) and expanded by application of axial force (FIG. 
4). 
As in the first embodiment described, the required actuation means for 
exerting pressure upon the element 101 to activate the sealing element 101 
can be created by other known means, mechanical, hydraulic, pneumatic or 
electric. Therefore, the term "actuation means" as used above or in the 
accompanying claims is to be interpreted as including not only the 
particular mechanisms disclosed but also their obvious alternatives.