Retention System for Submarine Cable without Armour Wires

The armour wires’ main function is to withstand the axial load exerted on the cable during installation and to connect the cable to the accessories and to the offshore structures during its operation. Moreover, they act as a protection layer against circumferential forces. In the absence of these elements, the temporary and permanent hang offs must be designed considering the unarmored cable’s capacity to withstand axial and circumferential compressive force.

As a result, the temporary HO was designed as a polymeric two-piece clamp, applying a uniform, controlled compressive force on cable. For the permanent HO, among various potential approaches, it was chosen to anchor the cable by molding a conical body of resin around the cores and securing it within a metallic, cone-shaped mold whose inner surface matches the resin’s profile. The mold serves two purposes: first, it is used to cast the resin to the required shape around the cores and once cured, it prevents the resin’s movement due to its opposite conicity. A crucial mechanism facilitating the connection between the resin body and the cable cores is the adhesion between the cable jacket and the resin. The interlocking between the resin body and the mold, combined with the adhesion, allows axial loads to be transferred to the mold. One of the main challenges was improving adhesion between the resin and the cable’s outer jacket, made of polyethylene (PE).

The first prototypes of this hang-off were successfully tested. The concept was validated when the hang-off withstood axial forces exceeding operational demands without compromising structural integrity or electrical performance. This article dives deeper into the various steps of the design and validation process and explores further optimizations to enhance its applicability for offshore static and dynamic cable installations.