intervention to replenish the gas in the event of component failure removal and repair or replacement of the unit may be necessary however this design can provide an efficient solution it is the basis that is used for developing the riser top tensile stress computations that are shown in fig e 4 b of the u s provisional patent application serial no 60 375 619 filed on apr 26 2002 this approach results in tensile stress increase primarily as the host facility approaches maximum offset limits even so the related maximum tensile stress remains well within acceptable limits most of the time host facility offsets will be much less than the extreme offsets and the tensile stress change is quite small the second approach is to use an u201c open u201d system for the pressurized gas that is used in the cylinder and rod assembly this method is represented in fig8 b this approach has the advantage that a constant level of gas pressure can be applied via the host facility resulting in the capability to maintain a near constant level of pressure on the cylinder and rod piston this allows maintaining a more constant top tensile stress at the top of the riser throughout the range of host facility movements however this additional capability comes at considerable additional cost and complexity with near certainty that the frequency of component failure removal or replacement of the unit is expected to be little different than for the closed system approach due to the added complexity of this system it could even.