Teco Tube Expanders Company

LUBRICATION, CARE AND MAIN­ TENANCE OF TUBE EXPANDERS The type of use demanded of tube expanders is severe and therefore these precision tools should be given a reasonable amount of care. For long, trouble-free and economical service the following is suggested: 1. Remove all rust, mill scale and other foreign matter from the inside and outside of the tube. Foreign matter on the inside of the tube will tend to become embedded into the tube wall and being abrasive may cause the rolls and mandrel of the tube expander to start breaking up. Mill scale or dirt left on the outer wall of the tube can cause damage to the tube seat and prevent the formation of a pressure-tight joint. Cleaning of the tube ends may be best accomplished by wire brushing or polishing. Remove any protective coating by washing with light oil or other solvents. NB: DO NOT LEAVE A RESIDUE OF LIGHT OIL ON THE OUTSIDE OF THE TUBE AS THIS MAY ALSO PREVENT A PRESSURE-TIGHT JOINT. 2. Before using, the expander should be washed in any commercial solvent to remove protective coatings, dirt, grease and other foreign matter. Make sure that the rolls and mandrel are in good condition and working correctly. 3. Before using, expander should be properly lubricated with a pressure resistant lubricant. We recommend using TECO ‘Lube-A-Tube’ . This water soluble lubricant was developed for tube rolling and may be mixed with water to the desired consistency. For small diameter and light tube gauges immerse the expander in TECO ‘Lube-A- Tube’ or light oil such as SAE 10 or 20. For large diameter and heavy gauge tubes, brush the expander with TECO ‘Lube-A-Tube’ or mixture of SAE 40 oil and graphite. 4. Expanders should be rotated at a speed proportionate to the tube size, gauge and length of tube seat. Tube materials must also be taken into consideration. The proper speed will provide a safe cold working of tube metal without crystallization or surface damage. Speed is also a major factor in expander life and if correctly set will prevent undue roller or mandrel breakdown. Ideal speed will keep to a minimum mandrel slip and the heat generated in mandrels and rolls when working. 5. After rolling each tube, clean and cool the expander in solvent or light oil and then properly lubricate the expander again. It is good practice to use two expanders so that one can be cooling whilst the clean expander is being used. 6. Inspect the rolls and the mandrel after rolling each tube. Replace any chipped rolls or mandrels immediately. A small chip in a roll can damage the entire expander, rolls or mandrel if not replaced at once. It can also damage the tube causing marks in the expand­ ed area which may necessitate tube removal. 7. After the job has been completed, the expander should be cleaned thoroughly with a commercial solvent or a light oil and stored in a manner which will avoid possibility of parts rusting. NB: DO NOT LEAVE A RESIDUE OF LIGHT OIL ON THE OUTSIDE OF THE TUBE AS THIS MAY ALSO PREVENT A PRESSURE-TIGHT JOINT. SOME GUIDELINES FOR TUBE EXPANSION Improperly rolled joints create additional expense to rectify. Under-rolling can be easily corrected merely by re-rolling, but over-rolling will require complete tube replacement. The optimum joint is one that develops a leak tight joint with adequate strength for the service intended with the minimum amount of cold working or reduction of the tube wall thickness. Experience indicates that joints of this type can be obtained with non-ferrous tubes in surface condensers by expanding to a wall reduction of 5% to 6%. This wall reduction is only achieved after metal to metal contact between the tube O.D. and the tube sheet hole. Steel tubes in heat exchangers may require wall reductions of 4% to 6%; soft copper and aluminium tubes in heat exchangers also require larger wall reductions in the area of 7% to 10%. A typical example of the application of this method is indicated for 3/4” x 18 gauge (19.05 x 1.24 mm) tube in a condenser. 1. Tube Sheet Hole = 19.30 mm (.760”) Tube O.D. = -19.05 mm (.750”) Clearance 0.25 mm (.010”) 2. Tube I.D. = 16.56 mm (.652”) Clearance = + 0.25 mm (.010”) I.D. Metal to Metal 16.81 mm (.662”) 3. 6% of 1.24 mm x 2 = 0.14 mm (.006”) Tube I.D. Metal to Metal = +16.81 mm (.662”) Expanded Tube I.D. 16.95 mm (.668”) LUBE-A-TUBE TECO Lube-A-Tube is a water soluble lubricant especially compounded for use with tube expanders. When rolling large or small, ferrous or non-ferrous tubes, use TECO Lube-A-Tube for smoother rolling and longer expander life, for clean tube ends after rolling simply wash with water. Tube Expanders for Condensers, Heat Exchangers and Boilers can of 5 kg (11.1 lbs). tube expanders company 4