Patent GB-1025489-A (GB)
Title: Abrasive blasting apparatus for the cleaning of tubes
Inventor: HILL ERIC JOHN
IPC: F28G3/00
Filed: 1964-03-23
Abstract: 1,025,489. Blasting. VACU-BLAST Ltd. March 9, 1965 [March 23, 1964], No. 12244/64. Heading B3D. Abrasive blasting apparatus for cleaning the internal surface of tubes, particularly removing deposit from heat exchanger tubes in oil refineries, comprises a first carriage having rollers thereon for free movement of the carriage longitudinally of the tube, a second carriage having rollers thereon for free movement of the carriage circumferentially of the tube, a gear upon the first carriage the input of which is driven by a motor and the output of which drives a supply tube joining the carriages and having a flexible coupling therein, and a blast nozzle mounted eccentrically on the second carriage at an angle to the axis of the tube and connected to the supply tube. An air motor 27, Fig. 2, and gear-box 3 are supported by two carriages 29 having rollers so as to run freely in the tube 6. Abrasive in a compressed air stream passes through hose 2, inlet tube 28 and tube 34 to an outlet tube 24 supported by a housing 32 rotated by the motor 27 through gears 30, 31 in the gear-box. The outlet tube 24 is coupled through a rubber hose 25 and lance 4 with the blast nozzle 5. The nozzle is carried in a holder 19 mounted eccentrically on a carriage 20 having two rollers 21 and a spring-mounted roller 22, the rollers engaging the bore of the tube 6. To indicate nozzle rotation, a switch 37 on the gear-box 3 is actuated by a cam on the housing 32 to cause an indicator light on a control panel 17, Fig. 1, to flash once per revolution. The assembly is moved along the tube by a longitudinal drive unit 7, Fig. 5 (not shown), co-operating with rigid lances 8 in short sections pinned together and attached to the motor 27. The drive unit 7 is clamped against the end of the tube with an interposed dummy length of tubing 39 so that blasting starts at the extreme end of the tube. Each lance section 8 has a chain rack 41 co-operating with a sprocket 42 driven, through a gear-box 43, by an air motor 44. Flanged rollers 45 are urged by a spring 46 to maintain driving mesh between the rack and sprocket. The roller assembly and gear-box 43 are mounted on pivots 47 so that they may be swung clear of the end of the tube 39. The hose 2 is connected to a blast generator 1, Fig. 1 (not shown). After the abrasive has been directed from the blast nozzle 5 it, together with the removed deposit, is conveyed along the tube by an air stream generated by a dust collector 9. The outlet end of the tube being cleaned is connected by a flexible hose 12 to the rear end of an adjacent tube 13 the front end of which is connected by a flexible hose 10 to a reclaimer 11 in which the removed deposit in the form of dust and large debris is separated by reusable abrasive. Dust passes to the collector 9; large debris is retained in the reclaimer for periodic removal; reusable abrasive is stored in the hopper 16. When the abrasive in the blast generator 1 has been used, the generator is switched off and abrasive is automatically transferred from the hopper 16. Additional abrasive, to replace that which is broken down and carried into the dust collector, can be added to the system from hopper 14 connected through valve 15 with the hose 10. A control 18 on the blast generator 1 is remotely controlled from the portable control panel 17 which also controls the air motors 27, 44.