The DRT is an active hydro-pneumatic type tensioner system so each stroke of the DRT should allow initial wellhead offset in accordance with the worst wellhead offset distance and offset tolerance with the worst load case combination. This worst case offset should be considered in conjunction with all possible offset positions of the platform itself that may result in possible upstroke of the riser.
The DRT should be equipped with a tension control and have adequate stiffness so that the tension imparted to the riser at maximum upstroke or downstroke results in constant riser support tension. As, appropriate, worst-case minimum tension (maximum upstroke) should be considered in conjunction with a failed tensioner element with appropriate load case.
Twisting of the DRT should be considered according to the maximum yaw that can be developed and should accommodate the stroking of the riser due to thermal effects.
The DRT should be designed in such a way that one load support unit can be replaced in the operating condition, as appropriate.