Plug assembly

A plug assembly for use in plugging a tube, comprising:

• a compression ring having an inner surface and an outer surface, said outer surface of said ring for contacting a tube inner diameter for forming a seal therewith;
• and
• a pin receivable within said ring for radially outwardly expanding and compressing said ring against the tube inner diameter when said pin is displaced axially through said ring;
• said pin extending longitudinally from a front end to a rear end and having an outer surface extending from said front end to said rear end, said front end having an outer diameter that is less than an outer diameter of said rear end such that said outer surface of said pin is tapered, said inner surface of said ring and said outer surface of said pin being disposed in confronting relation and being slidable relative to one another between said front end and said rear end of said pin;
• said pin having a nose section which includes said front end, a rear section which includes said rear end, and an intermediate section that extends from said nose section to said rear section;
• an outer diameter of said intermediate section increases along a length thereof from said nose section to said rear section such that an angle of taper of said intermediate section adjacent said nose section is greater than an angle of taper of said intermediate section adjacent said rear section;
• and
• a portion of said outer surface of said pin along said nose section tapers at a constant angle relative to a longitudinal axis of said pin.