Other

Cti Industries Corporation

Kevin W McParland

A method and apparatus for repairing a heat-exchanger of the type having a tube sheet in which the extremities of exchanger tubes are mounted. The method involves unrolling tubular insert stock from a supply roll, straightening the unrolled insert stock by passing it through a straightening device which has its output disposed substantially in alignment with one of the exchanger tubes to be repaired and at a location adjacent the mounted extremity of the exchanger tube, and forcibly pulling the straightened insert stock into the one exchanger tube. The pulled-in insert stock is then cut to length, and the ends radially expanded against the inner walls of the exchanger tube, and sealed to the tube sheet. The straightening is accomplished by a fixture having positioning pins receivable in adjacent ones of the heat exchanger tubes, such that the fixture can be manually positioned and thereafter held in place by the frictional engagement of the pins while the insert stock is being installed in the exchanger tube being repaired.

Process for repairing heat-exchanger tubes

Heat exchanger tubing has failure rates due to inlet end related problems in the 85-90% range. Such failures are normally limited to the first three to six inches of the tube inlet ends. The present method eliminates the problem without relining, removing, or sealing the tubes. The tube ends are first inspected and the condition of the inlet areas of the tubing determined. If the ends are eroded or corroded, the tube ends are cleaned down to the metal. Then a metallurgically compatible insert is installed in the damaged end and controllably roller-expanded to eliminate any end step at the downstream end as well as to prevent over expansion of the damaged tube and insert. The input end of the insert is flared to the existing inlet tube profile, thereby restoring the damaged area. This process eliminates totally replacing or relining the existing tubes. If erosion is severe, a bushing is inserted between the insert and the tube end and they are roller-expanded together. The tube may also be bored out to restore tube concentricity before the insert is installed. In another embodiment the damaged tube end is severed and replaced with a collar before the insert is installed and then roller-expanded to restore the damaged end.

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Fairfield, CT, United States of America

Kevin W McParland