STABILITY ENSURING OF PIPELINE DESIGN POSITION TAKING INTO ACCOUNT HYDRODYNAMIC IMPACTS

Abstract

Background Most subsea pipeline sections at water crossings are unstable and move out of their design position either during the testing period or in the first year of operation, or after long operation and frequent pumping stops. This confirms that the design of such sections does not take into account loss of stability, such as hydrodynamic or gas-dynamic impacts. Aims and objectives The aim of the studies is to ensure the stability of the design position of the pipeline taking hydrodynamic or gas-dynamic effects of the pumped product flow. For ensuring the stability of the design position of the pipeline in the convex section of the profile it is proposed to determine the hydrodynamic or gas-dynamic impact of the pumped product flow and to carry out the additional ballasting of the pipeline taking into account the intensity of hydrodynamic or gas-dynamic impact. Methods The forces of hydrodynamic and gas-dynamic influence of the pumped medium flow on the pipeline were determined with the use of the theory of classical mechanics, the theorems of force impulse taking into account the repulse from the air, the theorems of force impulse without taking into account the repulse from the air and the law of distribution of flow velocities. Results On the basis of the received dependences of change of a vertical component of force of hydrodynamic influence of a water stream from a pipe turn angle it has been established that the least error of a trend line between experimental and calculated data has the graph built on calculated results of impulses theorem taking into account a repulse from air.