The need for oil exploitation in ever increasing depths drives the development of structures suitable to resist very high loads. In this context, the qualification process for flexible flowlines involves physical testing to demonstrate suitable performance for the intended application and to obtain data to improve the applied design tools.
As part of the qualification process, lateral instability under external pressure and cyclic bending, known as lateral buckling (LB), was investigated for a 6-inch ID flexible pipe flowline with wet annulus conditions. This was done by performing reduced-scale prototype testing in a hyperbaric chamber with the application of cyclic bending and external pressure. The external pressure was adjusted to the application depth of the particular flexible pipe, in an attempt to replicate the typical conditions of a Deep Immersion Performance (DIP) Test. The benefit of DIP testing is that it realistically replicates the loading conditions that the flexible pipe will be subjected to during installation or operation. However, DIP tests are very expensive, whereas reduced-scale testing can be performed at much lower costs. A concern of reduced-scale testing is if these tests can duplicate the loading conditions of the DIP tests.
This paper will describe the testing program, results and its relation to the design methodology.