Introduction |
 
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Introduction |
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This example illustrates the use of Flexcom in an analysis to predict if upheaval buckling will occur in a pipeline installed in a water depth of 88.5m, for a user-defined seabed imperfection height and slug flow regime. The objective is not to demonstrate how such analyses should be performed as part of a pipeline design project; rather it is to show Flexcom can be readily and successfully employed in this type of study. To this end a somewhat simplified scenario is considered, as described in subsequent sections.
A multi-stage analysis procedure is employed, consisting of four static steps followed by a dynamic run which is the actual upheaval buckling analysis. The sequence of static analyses is used to develop a distribution of tension (or more correctly compression) in the pipeline. Such a distribution results from the pipeline weight in water, the seabed friction characteristics, the degree of pipeline end restraint, and the level of backfill. Classical pipeline calculations would be used in determining this distribution, a process which is not described here. In the analysis approach used here, the tension due to buoyancy, gravity and internal fluid is adjusted to the required distribution by the application of a temperature loading. This does not represent a genuine physical load condition, but is simply a convenient method to develop a used-defined compression distribution in the pipeline.
This example and the previous one in the manual (of an as-laid span) illustrate how Flexcom can be readily employed in analysing pipelines under various conditions. This present analysis also demonstrates the program facility to model multi-phase slug flow.