Internally finned tube

An internally finned tube for use as part of a heat-exchanging system comprising:

• an elongated cylindrical tube;
• an array of fins in the form of a hollow integral sheet metal cylinder having V-shaped corrugations, with the corrugation ridges extending parallel to the axis of the tube when said cylinder is inserted in the tube, the outer ridges of said cylinder being in contact with the inner surface of the wall of said tube for substantially the full length of said outer ridges, each of said outer ridges being notched at a plurality of spaced locations along their length, each notch being formed by the removal of metal at said ridge and for a predetermined depth therefrom toward each adjacent inner ridge, said notches being arranged in relatively widely spaced pairs, each notch pair comprising two very closely spaced notches which define therebetween a very narrow readily yieldable connecting link of metal bridging the gap between the notches of said pair and across the outer ridge, said outer ridges between said notched pairs being slit in a longitudinal direction to completely sever the two sides of each ridge from each other except for said connecting links, such severence leaving a clean-cut edge on the outer radial end of each fin for engaging it with the inner surface of the tube wall, one of either the cylinder or the inner surface of the tube wall being clad with a material having a melting point lower than that of either the base material of the tube or of the cylinder so that said sharp edges of the fins may be brazed to the inner surface of the tube, said fins being so disposed within the tube that fluid flowing from the tube may be in contact with both faces of each fin as well as with the inner surface of the tube wall.