Plug assembly for use in method and apparatus for repairing heat exchangers

摘要

A shell and tube type heat exchanger having a tube bundle supported at opposite ends in tube sheets is capable of being repaired quickly by closing off opposite ends of a damaged tube using the method and apparatus disclosed. The apparatus comprises a two-part tapered plug assembly which is adapted to be installed in the tube in alignment with the tube sheet and expanded radially outward into tight engagement with the interior of a tube by pulling an inner wedge portion of the plug assembly axially relative to an outer ring portion. The pulling is effected by an hydraulic ram which is connected by a breakaway unit to a pull rod which slides axially relative to a compression tube both of which are received axially within the defective tube. The hydraulic ram pulls the rod relative to the compression tube and thereby draws the wedge inside the ring until the breakaway connection releases the pull rod. A shorter length of compression tube and pull rod is utilized for plugging the other end of the defective tube and for plugging U-bend types of heat exchangers. A plug assembly which is particularly suited for use in closing off tubes lined with scale and/or corrosion has a sleeve with a series of circumferential cutting edges alternating with grooves. The edges sever the scale and displace the same into the grooves when the sleeve is expanded outwardly by the wedge.