Orcaflex 2rd limiting stress
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Such movement could occur if the disconnect were to occur at the “worst phase” of a vessel's heave cycle. Minimum tensions are limited by avoidance of contact between the LMRP and the BOP, as the LMRP cycles back downward toward the BOP after disconnect. The allowable limits on riser recoil set the following riser top tensions: minimum top tensions to keep the LMRP from damaging the BOP during disconnect maximum top tensions to avoid slack in the tensioner lines just after disconnect and maximum top tensions to avoid the riser impacting the drill floor. John Halkyard, in Handbook of Offshore Engineering, 2005 9.2.9.3 Allowable Limits
#Orcaflex 2rd limiting stress code
If additional bending stiffness is non-zero, OrcaFlex will automatically determine what proportion of each load (wall tension, bend moment, shear and torque) should be considered to contribute to the stress results and code check results, so that the reported loads are those carried only by the original line type structure and exclude the proportion due to the additional stiffness.James Brekke.
![orcaflex 2rd limiting stress orcaflex 2rd limiting stress](https://www.orcina.com/wp-content/uploads/2008/06/Soil-Model-Drawing.png)
This means that, unlike most data items, OrcaFlex allows you to modify these values after a simulation has been run. These results are derived after the simulation has completed: the stress loading factors do not affect the progress of the simulation. The stress loading factors only affect the wall tension results, stress results, fatigue analyses and code check results. To obtain stress estimates for the main pipe you would then set the stress outer and inner diameters to '~' and the bending and shear stress loading factors to 0.7. You might estimate that the main pipe takes all of the tensile and torsional loads, but only carries 70% of the bending loads, the other 30% being taken by the piggyback pipe.
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For example, consider a line representing a composite structure consisting of a main carrier pipe and an external piggyback pipe. In some cases, values less than 1 may be appropriate. See line pressure effects theory for more details.įor many cases, such as a simple homogeneous pipe that carries all the loads, these factors should be set to their default value of 1. Where $C_1$ is the tensile stress loading factor. The value of effective tension used in the code checks is calculated from the total, unscaled, wall tension, $\Tw$, as The stress loading factors also influence the effective tension used in calculating the code check results.
![orcaflex 2rd limiting stress orcaflex 2rd limiting stress](https://ars.els-cdn.com/content/image/1-s2.0-S0029801820307149-gr8.jpg)
The reported wall tension result is scaled by the tensile stress loading factor. Each of wall tension, bend moment, shear force and torque is multiplied by the corresponding stress loading factor in these results calculations. The stress loading factors define the proportion of each load (wall tension, bend moment, shear and torque) to be used in calculating stress results and code check results. A value of '~' here tells OrcaFlex to not draw any limit curve. This value is only used to draw a limit curve on stress range graphs it does not limit the stress achieved in the line. The maximum allowable stress for this type of line. For more complex cases, for example where the pipe outside diameter allows for added buoyancy modules that are not load bearing, the stress diameters can be set explicitly. For simple cases, the stress diameters can be set to '~', in which case they will be taken to be the same as the pipe diameters. They are used in the wall tension and stress results calculations, which are based on the assumption that the loads in the line are taken by a simple homogeneous cylinder. The stress diameters are the inside and outside diameters of the load-bearing cylinder.