Patent ID: 6966343

Claim:
A pipe plug apparatus for insertion and selective sealing engagement with the inner wall of a section of pipe, said apparatus comprising: a cylinder having a closed end; a piston slidably received within said cylinder so as to form a pressure chamber between said piston and said cylinder closed end; a rod having a first end connected to said piston and a second end projecting from said cylinder; a first compression plate radially projecting relative to said rod; means for fixing said first compression plate longitudinally relative to said cylinder; a second compression plate connected to said rod and radially projecting therefrom; at least one sealing member disposed between said first and second compression plates, said sealing member adapted to radially expand under axial compression; means for biasing said piston toward said cylinder closed end; means for pressurizing said pressure chamber; whereby application of pressure to said pressure chamber radially relaxes said at least one sealing member and release of said pressure results in radial expansion of said sealing member.