Dimensional parameters of corrugated sheathing for optical cables in the oil and petrochemical industry

Typical corrugated sheathing for armored optical cables features a corrugation height of around 0.5 mm and a pitch of 2.5 mm, with sheath thickness measured according to EN 60811-202 standards.Corrugated Steel Tape (CST) ParametersCorrugation Height: The initial set height of the steel tape in the sheathing machine is usually 0.8 mm, but after extrusion and assembly, the effective height inside the cable reduces by 30–40%, resulting in an actual corrugation height of approximately 0.5 mm .Pitch: The distance between adjacent crests or troughs of the corrugated tape is typically 2.5 mm .Material: Corrugated sheathing is commonly made from steel tape, sometimes combined with glass yarns, aramid yarns, or water-blocking/mica tapes for additional mechanical and environmental protection .Sheath Thickness MeasurementStandards: Sheath thickness is measured according to EN 60811-202, which specifies methods for testing non-metallic materials over both regular and corrugated surfaces .Measurement Tools: For corrugated metallic sheaths, a ball nose micrometer with a 1 mm radius and 0.01 mm accuracy is recommended. Alternatively, a measuring microscope or optical digital image analyzer can be used for precise readings .Sample Preparation: A cable sample should include at least two peaks and two troughs of the corrugation. A reference line is drawn parallel to the cable axis, and the minimum thickness is measured along this line .Additional Considerations for Oil and Petrochemical ApplicationsEnvironmental Durability: Cables often include gel-filled or gel-free loose tubes, water-swellable yarns, and flame-retardant LSZH jackets to withstand harsh conditions such as high temperature, chemical exposure, and mechanical stress .Compliance: Ensure that the corrugated sheathing and overall cable construction meet IEC 60793 and IEC 60794-3-10 standards for optical fiber cables in industrial environments .Inspection Tolerances: Due to manufacturing variations, the effective corrugation height may differ from the machine set value. Third-party inspections often require verification against the set value (0.8 mm), even if the actual height is lower .SummaryFor optical cables in the oil and petrochemical industry, corrugated sheathing typically has a pitch of 2.5 mm and an effective height of 0.5 mm, with sheath thickness measured according to EN 60811-202. Proper material selection, environmental protection, and adherence to IEC standards are critical to ensure mechanical robustness, chemical resistance, and long-term reliability in harsh industrial conditions.