Calculate high temperature pipeline upheaval buckling using either the Hobbs method, the Pipeng method, or the LRSTAR method.
The Hobbs method can be used for used for pipelines lying on the seabed. The LRSTAR and Pipeng methods are suitable for buried pipelines, and have been developed using the results from finite element analysis (FEA). The LRSTAR method uses a cubic spline fit for the dimensionless Richards length number and Richards weight number. The Pipeng method uses a simple mathematical relationship between the Calladine Length number and the Calladine load number based on beam theory.
The Hobbs method calculates the initiation temperature from the global axial load, the load outside the slip zone, and hence accounts for the expansion of the pipe prior to buckling. The Pipeng method and LRSTAR method calculate the initiation temperature from the axial load in the buckle, and do not account for the expansion of the pipe prior to buckling. The Pipeng method and LRSTAR method are therefore slightly conservative. In addition, the LRSTAR method includes a built in design factor. The LRSTAR method is therefore more conservative than the Pipeng method.
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