Method of repairing heat exchanger tube ends

Abstract

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.

Dependencies are inferred from the claim text.