Device for cleaning inner surface of heat exchanger tubes

A grit blasting device for cleaning tubes mounted perpendicular to top and bottom tubesheets, comprising:

• a positioning frame;
• a grit blast nozzle mounted on said positioning frame and projecting outwardly from said positioning frame, said grit blast nozzle defining a longitudinal axis and having an outlet to be directed into a tube opening of a tube during a cleaning operation;
• a plurality of stop pins mounted on said positioning frame and projecting outwardly from said positioning frame, said stop pins having distal ends which define an imaginary plane;
• wherein the grit blast nozzle is mounted on said positioning frame such that the longitudinal axis of said grit blast nozzle is defined relative and perpendicular to the imaginary plane defined by the distal ends of said stop pins;
• wherein with the grit blasting device placed opposite a tubesheet of the top and bottom tubesheets during the cleaning operation, the imaginary plane is parallel with the tubesheet, the longitudinal axis of the grit blast nozzle is essentially coaxial with the tube, and the distal ends of the plurality of stop pins are configured to abut the tubesheet and prevent the outlet of the grit blast nozzle from extending into the tube;
• and
• wherein the outlet of said grit blast nozzle is configured to create a venturi effect at a juncture of the outlet and a first tube portion nearest the tube opening of the tube being cleaned, whereby the first portion of the tube is treated with grit blast material.