Buckle Analysis Of Oil And Gas Pipelines

A big percentage of oil is transported using pipelines which usually run very long distances.It is therefore essential that these pipelines are strong enough to hold the oil they carry over long distances at the high temperatures and pressure.The oil is kept at high temperature and pressure so as to ease its movement,and to prevent formation of wax,and these pipelines are either laid on the ground or even buried to prevent damages from fishing and anchors.Pipelines usually have imperfections that occur during manufacture or even as they are laid down on the ground.Due to the high temperatures and pressures,the pipelines expand which leads to frictional compressive forces build up and later resulting into buckling.It is assumed that the initial imperfection leads to the buckling.In this paper,an analytical method is employed to study the buckle forces in relation to the amplitude of the buckle at the different initial imperfections.Dimensions of the pipeline like the pipe diameter are varied to see if they would have any effect on the buckling force.The resulting buckling length is also observed for the different pipeline diameters to see how it is also affected.Most work done in the analytical study is done using initial guesses taken by the engineer depending on their expertise.In this thesis,a comparative study is made to find out the relationship between the final buckle length and the initial imperfection.It is later discovered with a known initial imperfection of the pipe,one can actually be able to tell the buckle length.This very length can also be used to estimate the buckle force of the pipeline.A relationship between the diameter of the pipeline and the buckle length plus the initial imperfection is also got.ANSYS is used to carry out the Finite Element analysis and results got are compared to those got in ABAQUS.It is discovered that ANSYS can also be used comparably to ABAQUS.The soil model in this study is represented by springs with forces equivalent to those brought about by the soil cover and weight of the pipeline.These springs are evenly distributed along the pipeline to mimic the non-elastic behavior of the soil.Conclusions are made and recommendations for what further studies to be done are also given.The researcher hopes that more study can be made on the equation got with more data to minimize the errors got in the final answers.