Structural resistance and loading case analysis for buckling collapse prevention in thermoplastic liners for oil applications.

FEDERICO RUEDA; CAMILA QUINTANA; FRONTINI, P.M.

Advances on the Mechanical Behaviour of MaterialsComputational Modelling, Theory, and Experiments

springer

Año: 2024; p. 81 - 87

The buckling collapse induced by external pressure is themain failure mechanism in thermoplastic liners for oil applications. Thisphenomenon is caused by permeation of dissolved gases in oil throughthe polymer pipe thickness. This results in gas trapped into the annularcavity defined by the metallic host pipe and the external liner surface.During operation, the pressures of the annular and inner cavities remainin equilibrium. The problem may arise when depressurizing the pipeline,due to the resulting pressure difference between both cavities. If the linerstructure is not capable to bear the radial load, collapse buckling occurs.The damage grade depends on many factors that can be divided in twomain aspects: i) the liner resistance, related with its geometry, boundaryconditions and material behavior; ii) and the actual loading caseas a consequence of the compressible fluid in the annulus between linerand host pipe. Although both must be properly determined to predictstructure behavior, works on this subject are often concerned only withliner resistance. In this work, we propose a simple experimental methodto quantify the annular resulting space after liner fitting. This informationis then used to estimate the actual loading case. Finally, by usingpreviously verified numerical methods to predict the liner resistance, weestablish safe operation parameters in order to prevent buckling collapse.