Method for removing a metallic plug from a tube by simultaneously heating and stretching the plug

A method for removing a plug from a tube mounted in a tubesheet, wherein said plug includes an elongated cylindrical shell formed from a nickel alloy having a closed end and an open end, the interior of said shell including a tapered wall section, a well as an expander element that wedgingly coacts with the tapered wall section to radially expand the outer wall of the shell into engagement with the inner wall of the tube when the expander element is pulled from the closed end to the open end of the shell, comprising the steps of:

• a. pushing the expander element from the open end to the closed end of the shell;
• b. heating the tapered wall section to a temperature sufficient to lower the tensile yield thereof by at least 50 per cent by conducting an electric current across said wall section by applying an electric current through said wall section with a pushing means;
• c. applying a tensile force across the tapered wall section with said pushing means that is sufficient to elastically elongate the plug shell along its longitudinal axis so that the engagement between the outer wall of the shell and the inner wall of the tube is reduced, wherein said tensile force is applied while said tapered wall is being heated to said tensile yield lowering temperature;
• d. disconnecting said electric current from said wall section and allowing said wall section to cool and thermally contract further out of engagement with said tube;
• and
• e. pulling said plug from said tube.