Method for remotely marking a defective heat exchanger tube

摘要

A remotely controlled tool for marking the location of defective tubes in a heat exchanger tube sheet, comprising an axially extensible pilot which is extended into and retracted from the defective tube to be marked by means of an internally threaded captive nut, which is attached to the pilot and is in threaded engagement with an externally threaded drive screw. The drive screw is driven by a reversible drive motor. Marking of a tube is accomplished by means of a paint-saturated annular felt marking pad carried in a cylindrical sleeve which surrounds and is axially slideable with respect to the pilot. The marking pad is driven outwardly along the pilot to engage the tube sheet surrounding the defective tube and is retracted after the marking function has been performed by means of a solenoid. The entire marking tool is carried on a conventional remotely controlled arm mounted in the heat exchanger header compartment, and the tool is positioned opposite the defective tube to be marked by means of the remotely controlled arm with the aid of a television camera mounted on the arm.