Below is a list of links to OrcaFlex example topics. Within each topic are a number of examples which each comprise one or more simulation files, a description pdf file, workspace files and sometimes other supporting files. The files for each example are zipped for easy download. The simulation files can be opened and viewed with the demonstration version of OrcaFlex.
In these examples, two different methods of modelling a simple rigid stinger are presented. Both use the pipelay supports method, with one model using a simple supports geometry, and the other using an explicit method. The explicit method provides some additional features which are described in the relevant section of this document. The two models have been created using an identical pipeline and vessel, and the rollers have been positioned in the same places to allow direct comparison of the results.
This model represents a rigid stinger hinged off the back of a lay vessel using the pipelay supports feature. In addition to the lay pipe, another line is included to model a cable 'piggybacked' to the pipe.
As the interaction between the lay pipe and the stinger can tolerate axial movement of the pipe, this model allows the pipe to move in and out of the two tensioners. The model therefore represents the situation where welding operations have been suspended and the pipe is moving relative to the vessel so as to limit stresses. Modelling both tensioners is not generally necessary, but it has been done here to demonstrate how easily it can be done. A third tensioner is included on the piggyback line.
The pipe has also been assigned some code check data to allow a check against DNV OS F201 to be performed.
This model represents a stinger hinged off the back of a lay vessel, as per the example E02. Here, the stinger is modelled using an arrangement of lines connected together, providing a more accurate representation of the true structural and hydrodynamic properties of the welded steel framework.
As the interaction between the pipeline and the stinger can tolerate axial movement of the pipe, this model allows the pipe to move in and out of the tensioner. The model therefore represents the situation where welding operations have been suspended and the pipe is moving relative to the vessel to limit stresses.
This model represents a three-section articulated stinger with roller boxes, hinged off the back of a lay vessel. The stinger is detailed using an arrangement of single segment lines which provides an accurate representation of the true hydrodynamic properties of the welded steel framework. The stinger lines are connected to 6D buoys with negligible properties.
Previous examples in this set have treated each roller box on the stinger as a single support. This approach will be quite satisfactory for many applications, but it is not a precise representation of reality because each roller box typically consists of a set of rollers attached to a frame that is able to pivot slightly relative to the stinger. In this example, we model the roller boxes in detail.
The free end of a steel pipe is lifted from the seabed by davits to bring it alongside a workboat. The lift is modelled dynamically in small waves and no current.
This example demonstrates how the OrcaFlex automation tools can be used to create installation lay tables.
A basecase model is analysed to determine the range of top tension values within which the lay operation can proceed. To find the limiting tensions, a range of pipe (or umbilical) spans from ship to touchdown are analysed statically to find the cases where one or more of the acceptance criteria is infringed. Once the limits are found, a set of intermediate cases are analysed, and results are reported to a lay table, which clearly indicates the acceptable / unacceptable cases.
