1,144,242. Finned heat-exchange tubes. MASCHINEN - UND APPARATEBAU SCHKEUDITZ VEB. 26 Feb., 1966, No. 8553/66. Heading F4S. [Also in Division B3] A method of making a heat exchanger tube bank from a single length of tubing comprises the steps of forming on the tube by rolling, a single helical fin 20 which is reduced in height at axially-spaced portions of the tube length, annealing these portions and bending the tube to form the tube bank. The fins of reduced height may be formed by machining portions of a smooth tube before rolling the fins or by retracting the fin-forming rolls at intervals during the rolling operation. The rolling of the fins simultaneously raises a helical fin 6 on the inside of the tube of the same pitch as that of the outside fin 20. The tube may be formed of aluminium or other light metal.