Corrugated Metallic Cable Sheath

The helically corrugated, impervious, steel sheath is formed around the cable core, welded and corrugated in a continuous operation. This manufacturing method eliminates the thermal problems of the extrusion process, the length restrictions of the sinking or draw-down system, and also increases the pliability and the radial strength of the sheath. The sheath is an impervious barrier to gases and fluids which also gives mechanical protection to the cable core. Corrugation designs are based upon an engineering balance of weight, thickness of metal, pliability, compression strength, and ability to withstand internal and external pressures. The method of corrugating is flexible, and special designs can be made for specified service conditions. Even with thinner sheaths than commonly used for other types of impervious sheaths such as lead and aluminum, the corrugated steel sheath has improved radial strength and resistance to "sheath metal fatigue." Conduits, ducts, and similar accessories are not necessary to protect the cable. Service records and laboratory tests substantiate the fact that the corrugations do not damage cable cores either during the manufacturing process, installation, or service. Cables protected with the corrugated steel sheath have bending characteristics which permit them to be shipped on normal diameter reels and to meet the normal installation requirements of minimum radii and number of bends. The sheath can be bent much sharper without damage to itself than recommended by industry standards for various insulations and cores. Protective systems for the sheath have been developed for chemical and corrosive environments.