ASSESSMENT OF THE OPERABILITY OF AN OIL COLLECTION PIPELINE OPERATED IN THE CONDITIONS OF THE FAR NORTH

Ensuring reliable and safe operation of field oil pipelines is the most important strategic direction for the stable development of regions remote from the central part of the Russian Federation. The peculiarity of the operation of oil collection pipelines in the Far North is associated with a harsh climate (low temperatures, high humidity, long winter (from 6.5 to 9 months) and short summer periods), difficulty in maintenance due to remoteness and inaccessibility. Oil collection pipelines are operated under conditions of changing pressure of the pumped fluid, vibrations, and cyclic loads. One of the main causes of pipe failure is corrosion damage as a result of both internal and external corrosion. This article examines the effect of low-cycle corrosion fatigue on ensuring a stable pipeline operation and preventing the occurrence of various emergency situations. An important engineering task is to determine the rate of crack development under various operating conditions and conditions of equipment and to assess the durability of metal structures. Corrosion and fatigue failure of equipment is a serious problem that occurs as a result of crack formation, their growth and uncontrolled equipment breakage. The influence of factors such as stress concentration, structural features of the material, composition and time of exposure to a corrosive environment determine the fatigue resistance of the material. The authors' earlier studies of the structural and mechanical properties of materials of oil and gas equipment operated under conditions of complicating factors and a corrosive environment showed changes in the mechanical characteristics of the equipment material. As a result of simultaneous exposure to mechanical loads, including cyclic, and corrosive media, the tensile strength, yield strength and hardness of the equipment material are significantly reduced.The purpose of the study is to predict the resource of a field oil pipeline with crack-like defects operated in the conditions of the Far North. The tasks for achieving the set goal are defined: — according to the data of the technological services, determine the operating conditions of the oil collection pipeline; — to analyze the chemical composition of the material in order to determine the grade of steel; — to establish the effect of changes in the depth of the crack in the pipeline on the stress intensity coefficient K; — select the dependence of the crack growth rate on the stress intensity coefficient, taking into account the steel grade and the operating conditions of the pipeline; — to assess the resource of the oil collection pipeline with identified defects.