• MUX Cable Tensioner

    Mux cable tensioners are used onboard floating drilling rigs to maintain a near-constant tension in the upper part of the mux cable, which is the multiplexed power and communication umbilical between the rig and the subsea BOP (blow-out preventer). This saves the mux cable from heave-induced strain and material fatigue and ensures reliable command lines to the BOP.

    Description

    Our proven mux cable tensioner maintains tension by resting the cable in a hang-off saddle suspended in the wire from a single wireline tensioner unit.

    The tensioner unit consists of an air control cabinet, working air pressure vessel (PV), air/fluid accumulator, anti-recoil valve, and an upward-stroking plunger cylinder with three wire sheaves at the rod end and three at the lower end. After installation of the mux cable, the cylinder extends to mid-stroke by pressurizing the working PV from external standby PVs. The cable rests on a cushioning air spring that automatically and passively counteracts the heave and maintains the cable tension. The average maximum wire tension at the hang-off saddle is 2 metric tons.

    The most common cylinder stroke is 2.8 m, which due to the wire reeving, translates to 16.8 m of wire travel at the hang-off saddle. A fluid fill unit is needed for initial filling of water-glycol based tensioner fluid, and for topping up and fluid change, but can normally be shared with the riser tensioner. Compressors and standby PVs for the external process air supply can also normally be shared with the riser tensioner. 

     

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