Cam-assisted, wedge actuated, metal-to-metal seal, block and bleed plugging tool

1. A method of plugging a pipeline employing a cam-assisted, wedge actuated, metal-to-metal seal, block and bleed plugging tool comprising the steps of:

(a) sealably securing onto the exterior of the pipeline first and second spaced apart collars, each collar having a sealing face in a plane perpendicular the pipeline axis;

(b) cutting and removing a length of pipeline from between said collars leaving two open pipe ends;

(c) positioning first and second seal cups between said collars, each seal cup having on a forward face a forwardly extending circumferential lip of internal diameter greater than the external diameter of the pipeline, each seal cup having a top and a bottom cam followers; and

(d) moving opposed sides of a wedge against rearward faces of said seal cups to force said seal cups apart from each other and said circumferential lips thereof into metal-to-metal sealing engagement with said sealing faces of said collars, closing said pipe.

2. A method of plugging a pipeline according to claim 1 employing said top and bottom cam followers to guide the movement of said seal cups as said wedge is forced between rearward faces of said seal cups.

3. A method of plugging a pipeline according to claim 1 including:

retaining said seal cups between a top support and a bottom support, the top support having a pair of opposed cam slots therein slidably receiving said top cam follower of each said seal cup and the bottom support having a pair of opposed cam slots therein slidably receiving the bottom cam follower of each seal cup; and

forcing said top and bottom supports towards each other to guide said seal cups away from each other.

4. A method of plugging a pipeline according to claim 3 wherein said seal cups, said top support and said bottom support and said wedge are transported as an assembly into and out of positions between said collars.

5. A method of plugging a pipeline according to claim 1 wherein steps (b), (c) and (d) are carried out within a containment housing secured to said collars.

6. A method of plugging a pipeline according to claim 4 wherein said assembly is transported into and out of position between said collars by means of a rod moved by a piston reciprocated within a cylinder.

7. A method of plugging a pipeline according to claim 6 wherein said rod moved by said piston reciprocated within a cylinder is laterally movable but non-rotatably supported relative to said cylinder.

8. Apparatus for sealing openings through opposed first and second spaced apart paralleled toroidal collars having facing planar toroidal sealing surfaces employing a cam-assisted, wedge actuated, metal-to-metal plugging tool comprising:

a pair of seal cups each having a forward face having a circumferential seal surface dimensioned to fit said toroidal sealing surfaces;

upper and lower cam followers affixed to each said seal cup rearwardly of said forward faces;

a top and a bottom support each having a pair of cam slots for receiving said cam followers and configured to guide said seal cups towards and away from said toroidal sealing surfaces;

translation apparatus for moving said top and bottom supports towards and away from each other to thereby guide said seal cups towards and away from said toroidal sealing surfaces; and

a wedge forcably positionable between rearward surfaces of said seal cups.