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Results

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Once the analysis has been successfully run, you can view various reports and results by clicking on the Results tab of the Analysis component and selecting the relevant buttons. Note that you must first select the stage of interest from the Stage drop-down list in order to view the results appropriate to that particular stage.

Reel-Lay Analysis

The initial static analysis in this example corresponds to stage number 1. Results for this analysis are presented in the first three figures below. The parameters of interest are plotted against the curvilinear distance along the pipeline from the vessel connection point ‘Lay Vessel_Reel-Lay Ramp’.

The effective tension distribution along the pipeline is shown in the first figure. It starts at a magnitude of approximately 510 kN at the connection point, but immediately begins to decrease linearly through the reel-lay ramp, continues to decrease at a lesser rate through the sagbend region, until it becomes constant at the seabed.

The bending moment distribution is presented in the second figure. The most severe moments occur in the touchdown zone. Relatively small peaks are evident at the lower supports on the tower. The maximum moment experienced is approximately 370 kNm.

The maximum Von Mises strain distribution is plotted in the third figure. Similar to bending moment, the most severe strains occur in the touchdown zone. The maximum strain experienced is between 0.05% and 0.06%.

Effective Tension Distribution

Effective Tension Distribution

Bending Moment Distribution

Bending Moment Distribution

Maximum Von Mises Strain Distribution

Maximum Von Mises Strain Distribution

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The final results for the subsequent restart installation stages, the static and dynamic reel-lay stages, are very similar to Stage 1 for the effective tension, bending moment and Von Mises strain distributions. These similarities are highlighted on the superposed graphs shown in the first three figures below. The only notable differences in the restart stages are that the pipeline has been paid out by 100m and a surge offset of 100m has been applied to the vessel. The last figure shows the effect of these changes on the structure snapshots.

Note that if the pay-out or surge movement/velocity was somewhat different then the final results across all stages would likely be different.

Effective Tension Distribution Comparison

Effective Tension Distribution Comparison

Bending Moment Distribution Comparison

Bending Moment Distribution Comparison

Maximum Von Mises Strain Distribution Comparison

Maximum Von Mises Strain Distribution Comparison

Structure Snapshots Comparison

Structure Snapshots Comparison

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DNV Postprocessing Analysis

The results of the DNV Postprocessing for local buckling checks are detailed in the table below. As can be observed, the overbend and sagbend checks pass in both the static and dynamic reel-lay stages, with the actual check values being similar.

Table: Local Buckling Checks for Reel-Lay Stages

Stage

Max. Overbend Check

Max. Sagbend Check

Status

2

0.0202

0.5965

Pass

3

0.0203

0.6054

Pass

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