To increase the safety and reliability of pipelines and to assess their service life and to predict their durability it is necessary to analyse the serviceability of pipeline members taking into account their actual operating loads at various time periods. The Paper offers an analysis of the actual operating loads acting upon oil and gas pipeline members and their failures in the process of operation. It shows the variations in the workload of the pipelines transporting oil and gas, as well as pump station pipelines and the dependence of the physical causes and mechanisms of failures on the nature of acting loads. the The Paper also analyses the criteria and design diagrams for the evaluation of the durability of pipeline members in the conditions of actual random loading taking into account the low and high-frequency components of the stress variables. The Paper shows the need to consider the nature of loading while specifying the defect acceptance levels for various-purpose pipelines.
Concord of Independent States is currently operating a large-scale network of oil and gas pipelines totaling over 250,000 km. The pipelines were designed basically taking into account the need to ensure the structural strength of the pipeline under the internal pressure static loading of transported product. the The analysis of failures indicates, however, that in some cases the initiation and propagation of pipeline member failures in the process of operation cannot be explained on the basis of their insufficient strength under static loading. There are some cases of fatigue failures while running oil-product pipelines and pump station pipelines. Therefore, it is of interest to analyse the actual operating loading and serviceability of pipeline members used for various purposes, as well as the criteria and design diagrams used to evaluate their strength and durability under various workloads.
