Ensheathing

Ensheathing is the process of surrounding an object with a sheath or protective covering. The resulting item is said to be ensheathed. A sheath may be an outer jacket, insulation, or armor, and is applied to provide environmental protection, mechanical protection, and, in some cases, electrical or thermal insulation.

In electrical and communications systems, ensheathing is most visible as the outer jacket of cables and wires. The sheath—often made of polymers such as PVC or polyethylene, or of metal—provides moisture barriers, chemical resistance, flame retardance, and abrasion protection. In fiber optics, jackets and armor protect the delicate core from damage and environmental factors.

In piping and construction, ensheathing refers to an outer protective layer around pipes or conduits. The sheath shields against corrosion, impact, UV exposure, and temperature variations. Metal sheaths are common on high-pressure or corrosive-service lines, while polymer jackets are used for water, gas, or chemical lines, sometimes with additional thermal or acoustic insulation.

Materials and methods: common sheath materials include PVC, polyethylene, cross-linked polyethylene (XLPE), elastomers, and metal such as steel or aluminum. Application methods include extrusion, overmolding, wrapping with tape and adhesive, or cladding. The choice depends on operating temperature, chemical exposure, mechanical loads, and compatibility with the contents.

Considerations and maintenance: selecting a sheath involves assessing contents, temperature range, environmental exposure, installation constraints, and service life. Proper termination and sealing at terminations are required to prevent ingress of moisture or contaminants. Repairs may require cutting back and re-ensheathing or replacing the affected section.