Abstract: A process is taught for producing plastic jacketed cable for use in underground ducts exposed to unusually high temperatures and having a corrugated metallic shield which imprints the plastic covering includes an inner jacket capable of providing and maintaining adequate strength properties notwithstanding imprinting thereof by the corrugations of the shield contiguous thereto and an outer jacket superimposed over the inner jacket and suitable for resisting degradation while being exposed to elevated temperatures for sustained periods of time.

Abstract: A gas feeder pipe assembly includes a central duct capable of functioning as a gas feeder pipe and a plurality of pairs of electrical conductors in a unitary structure. The gas feeder pipe is located at the center of the structure, and the conductors surround the pipe in an oscillating lay. The pipe and the conductors are wrapped in a polyester film and enclosed in a coated aluminum sheath. A polyethylene jacket bonded to the aluminum sheath provides the outermost protection for the assembly.

Abstract: A cable core advances through an extruder head and then past an ultrasonic test set. In the extruder head, an annular plastic jacket is formed about the core. The test set generates four signals which correspond in magnitude to the jacket thickness in orthogonally spaced quadrants of the jacket. The signals are then applied to apparatus for centering the core with respect to the extruder head. Additional apparatus generates control signals in response to the signals from the test set. The control signals are applied to a mechanism for adjusting the jacket thickness in diametrically opposite quadrants with respect to the thickness in the quadrants adjacent thereto to control the uniformity of the jacket thickness. The control signals are also applied to a mechanism for controlling the overall jacket thickness. The signals give priority to the function of controlling the uniformity of the jacket thickness before the overall jacket thickness is reduced to a predetermined thickness range.