Abstract: A process for the manufacture of tubes made of fluoro resin, especially of polytetrafluoroethylene, which can be employed especially as corrosion-resistant coatings for piping components, in particular those made of steel, for conveying chemical products.

Abstract: A process for the manufacture of a thin-walled tube of fluorinated resin, particularly polytetrafluoroethylene, in which a ribbon of fluorinated resin obtained by lubricated extrusion and calendaring, is wound into a tube on a mandrel, the winding of the ribbon being performed in a plurality of layers, and the thus-wound ribbon on the mandrel being brought to a temperature above the sintering temperature of the fluorinated resin for sufficient time to produce sintering. The wound tube and the mandrel are cooled; while on the mandrel the thin-walled tube is rolled to elongate the tube, to reduce the thickness of the tube, and to increase the inside diameter of the tube; and then the mandrel within the tube is extracted.

Abstract: Multi-party conferencing apparatus for use in a pulse code modulated, time division multiplexed telephone communication system including a data bus on which operating times are divided into equal frames of time and each channel of a plurality of channels has a transmit time slot and a receive time slot in each time frame. Voice signals on conferencing channels are sampled in each time frame and compared in the conferencing apparatus with the highest amplitude sample being rturned to all conferencing channels except the channel on which it originated and a second highest amplitude sample being returned to the channel originating the highest sample.