E01 Simple rigid stinger.zip (11.3 MB) – Description PDF
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 method, and the other using an explicit method. The two models have been created using an identical lay pipe and vessel, and the rollers have been positioned in the same places. The results are therefore directly comparable.
E02 Rigid hinged stinger.zip (10.4 MB) – Description PDF (file not found.)
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.
Because 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.
E03 Detailed hinged stinger.zip (19.9 MB) – Description PDF
This model represents a stinger hinged off the back of a lay vessel, as per example E02, but with the stinger detailed using an arrangement of lines connected to 6D buoys (the buoys being assigned negligible properties), providing a more accurate representation of the true structural and hydrodynamic properties of the welded steel framework.
Because 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 tensioner. 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. Note the interaction between lay pipe and rollers is frictionless.
E04 Articulated stinger.zip (68.9 MB) – Description PDF
This model represents a three-section articulated stinger hinged off the back of a lay vessel. Each section of the stinger can hinge relative to the adjoining sections.
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 actually 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.
E05 Pipe davit lift.zip (31.1 MB) – Description PDF
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.
E08 Lay table automation.zip – Description PDF
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.