Abstract: A method of repairing a defective portion of a tube which is one of a plurality of generally parallel elongated tubes includes severing an axial portion of the tube which contains a defective portion, bending the free end portions of the tube disposed adjacent to where the axial portion which was severed, and securing an insert tube to the free end portions of the tube disposed adjacent to where the removed axial portion was located to thereby establish a passage for free flow of fluid within the repaired tube. In a preferred embodiment of the invention, the free end portions will be bent in substantially the same direction about 20 to 60 degrees with respect to the longitudinal axis of the tube when the tube being repaired is part of a water wall of a fossil fuel fired boiler and the repair is effected from the cold side thereof.