MACHINES FOR TREATING WEBS OF FLEXIBLE MATERIAL, SUCH AS ADHESIVE TAPE, METALLIC OR PLASTIC FOIL, PAPER AND/OR TEXTILE MATERIALS, SAID MACHINES BEING USED FOR WETTING, DRYING, COATING, LAMINATING, IMPREGNATING, IMPRINTING, EMBOSSING, CROSS-LINKING AND CHEMICAL SURFACE ACTIVATING; PARTS FOR THE ABOVE MACHINES, NAMELY ROLLERS, BEARINGS, SLOTTED NOZZLES, BLOWERS, HEAT EXCHANGERS AND POWER-OPERATED SQUEEGEES; MECHANICAL AND CONTACT-FREE WEB CONVEYORS