Estimation of temporary decommissioning impact on reliability and durability of oil pipelines

Abstract

Purpose: Due to changes in the volume of oil transportation, part of the pipelines must be temporarily decommissioned. The purpose of the work is theoretical and experimental study of pressure fluctuations during operation of oil pipelines and their impact on the durability of the pipeline material in work state and after temporary decommissioning (conservation). Design/methodology/approach: The results of oil pressure fluctuation research have given a chance to choose the terms of experimental research providing of the pipe metal mechanical features changes research during oil pipeline exploitation. Findings: Fatigue test modes are selected based on the calculations of the mathematical model developed. Experimental studies of the dependence of the fatigue strength of the pipe material on the conditions of operation have been carried out, which made it possible to determine the parameters of the fatigue curve of the samples. Has been defined that fatigue strength for the new metal pipe samples is more for 20-25% than for the metal samples which had the contacts with lime milk and for 30-40% more than for metal samples which were under exploitation. Research limitations/implications: In the future, more combination of "pipe material – preservation medium" should be explored to establish pain of general regularities. Practical implications: The probabilistic curves of the pipeline non-destruction are constructed, which will be used for practical calculations of the reliability and durability of the 13G1S-U steel pipelines. Originality/value: Mathematical model is made that describes non-stationary oil moves in oil pipeline, that has been caused by jump like changes of oil supply in oil pipeline, on this basis was defined, that oil pressure in oil pipeline provides within non stationary process in a range of 0.4-0.6 Hz frequency and amplitude fluctuation of pressure is 0.1-0.5 MPa.