Sleeving of tubes of steam generator

Abstract

Apparatus for processing the damaged tubes of a steam generator. This apparatus includes a sleeving tool for inserting sleeves in the tubes, a high-roller tool for rolling the sleeves at their upper ends where they have been expanded, and a low-roller tool for rolling the sleeves at their lower ends in the tube sheet. Each tool is provided with locking pins which engage tubes adjacent to a tube to be processed and suspend the tool in processing position. The sleeves are inserted in the tubes and are rolled by rolls driven by a hydraulic motor. For sleeve insertion and for high and low rolling, the motor is controlled by a servo control valve. The feedback signal to this valve is derived from a flow transducer in the feed line for the motor. The feedback for the force of sleeve insertion is the pressure across the motor derived from pressure transducers in the conductors through which the motor is supplied. For insertion speed and for rolling speed, the feedback is derived from a fluid-flow transducer. The passage of fluid through the servo valve is capable of varying continuously responsive the controlling error signal. The cage or roll tube and mandrel of the low roller are advanced into the sleeve by a piston of a hydraulic cylinder. The flow of fluid to the locking pins and to this hydraulic cylinder is controlled by a directional control valve.