The paper presents the results of the calculation of the safety factor for main gas pipeline sections, taking into account the random nature of the external load and the yield strength (σТ) of the pipes material with various grades. Based on the actual values of the safety factor, the current level of main gas pipelines sections reliability was assessed. The necessity of taking intoaccount the individual laws of yield strength distribution of the material of pipes with various grades used at construction stage of gas pipeline when determining safety class of pipeline section is substantiated.
The paper presents the results of calculating the stresses in the wall of an underground pipeline loaded with single weight in the angles of rotation on convex sections of the pipeline. Taking into account the random nature of the yield strength of tube steels, samples of actual values obtained for the material of pipes from different manufacturers, the strength of curvilinear sections of the main pipeline was evaluated. The necessity of individual selection of the weight of a single weight for each section of the pipeline is justified taking into account the specific law and the dispersion limits of the yield strength of the pipe material used during the construction phase of the section.
The rising cost of electricity, as well as the rapid development of technology and technology has led to the emergence of more advanced and energy-efficient equipment used in the main transport of oil. Thus, there is an urgent issue in the energy control of equipment to reduce operating costs. This article discusses the methodology for assessing the energy efficiency of the main oil pipeline.
Hydroelastic systems can be characterized by the simultaneous manifestation of elastic and hydrodynamic instabilities and their interaction. Consideration is given to mutual effects of gas pipeline bending, internal and external pressures, action of the compression force and fluid with a set density flowing along the pipe, axisymmetric expansion of a pipe and its longitudinal shortening, change of temperature of a wall of a pipe. The smallness of inertial forces is conditioned by a relatively slow change of disturbances under slowly changing external effects (compressive forces in the pipe, hydrostatic forces, velocity of gas motion in the pipe). External effects can be both independent and interconnected with each other. Here, the static mutual influence between those instabilities is called the instability interaction in a gas pipeline. We have obtained the linearized equation of the gas pipeline bend and the critical value of the force that squeezes the gas pipeline, which represents a generalization of the classical critical value for the static longitudinal compressive force acting on the pipe in the Euler problem due to the action of pressures inside and outside the gas pipeline and the gas motion inside the pipe, axisymmetric expansion of a pipe and its longitudinal shortening, change of temperature of a wall of a pipe. The investigation is focused on static instability interactions depending on the compression force in the gas pipeline, internal and external pressures and gas velocity, axisymmetric expansion of a pipe, change of temperature of a wall of a pipe. Bending rigidity, tensile forces and external hydrostatic pressure stabilize the pipe. By contrast, compressive forces, internal hydrostatic pressure and gas movement inside the pipe at any velocity, increase in temperature of wall of pipe have a destabilizing effect.
Despite the constant development of technologies, alternative methods of protection and chemicalization of all production processes, internal corrosion of pipelines remains a key problem for the management of pipeline operation of all oil-producing organizations. The authors developed an Autonomous device for constant supply of the required volume of concentrated reagent in the pipeline, without reference to infrastructure, roads and power lines. The main market segment for the developed device-areas with lack of infrastructure, lack of power lines and access roads, as well as during seasonal off-road.
The study was carried out to study the temperature gradient distribution in the cross section of the oil pipeline wall section during the repair of corrosion damage to the outer surface of oil pipelines by welding. As a result of the studies it was found that in a certain range of values of linear energy in the heated section of the pipe wall it is possible to obtain a zone of guaranteed strength properties, the metal in which has a margin of temporary resistance to rupture. Also, the dependence describing the temperature change of the inner surface of the pipe wall at different values of the linear energy and the residual thickness in the repair area by welding is obtained.
Abstract The paper presents the results of calculating the stresses in the wall of an underground pipeline loaded with single weight in the angles of rotation on convex sections of the pipeline. Taking into account the random nature of the excess internal pressure p, the sample of the actual values of which were obtained at the pipeline operation stage, the strength of the curved sections of the main pipeline was evaluated. The necessity of individual selection of the weight of a single weight for each section of the pipeline is justified taking into account the specific law of distribution and the limits of dispersion of internal pressure in this section. Materials and methods Calculation of stresses in the pipeline and verifi ation of the fulfi lment of the strength condition of the loaded curvilinear section of main pipeline was carried out on the basis of construction norms and rules (SNiP 2.05.06-85 * Trunk pipelines). Evaluation of the strength of curvilinear sections of main pipelines in the probabilistic aspect is performed on the basis of processing random variables using methods of probability theory and nonparametric statistics. Results The implementation of the probabilistic approach made it possible to estimate the strength of the pipeline based on the actual initial data, which are of a random nature and the distribution laws specific for each section of the pipeline. The presented approach allows to provide individual selection of single weight for each of curvilinear sites at repair or reconstruction taking into account specificity of the external loading acting on the pipeline at a stage of its operation Conclusions 1. Selection of the weight of a single weight placed directly at the top of the angle of rotation of the curvilinear main pipeline section ensures a reduction in the magnitude of the maximum longitudinal stresses arising in the pipeline wall to a standard level. 2. The considered approach to the evaluation of the strength of main pipeline allows to calculate the stresses of the loaded sections of underground pipelines and justify the choice of the weight of a single cargo, taking into account the random nature of the excess internal pressure p. 3. Due to the random nature of the excess internal pressure p, the choice of the weight of the loads that ensure the fulfi lment of the strength condition for the curvilinear sections of the main pipeline must be carried out taking into account the dispersion limits and the distribution laws for the random variable p, which are individual for each of the sections. 4. Accumulated in the process of monitoring of technological parameters during the operation phase of the main pipeline, information on the values of the excess internal pressure and the limits of its change for each linear section makes it possible, based on the approach considered, to clarify the weight or to change the arrangement of the supplies at the stage of reconstruction or repair of the linear part.
The article reviews a pneumatic impact method of cleaning of the heat exchange equipment, and a combined treatment of the surfaces to be cleaned with pneumatic impact and chemical treatment of the internal surfaces. A test bed was created to imitate different modes of equipment cleaning when developing the method.
The article is devoted to the study of the problems of changing the trajectory of the wellbore at the boundary of the change in the physical and mechanical properties of the drilled soils during the construction of the main pipelines by the method of directional drilling. The article discusses the interaction of the rock cutting tool with the extensionof the pilot well with the drillable soils and describes the mechanism of formation of the ledges in the borehole that change theeffective diameter of the constructed wellbore and lead to an increase in traction forces while dragging the pipeline into the well.
Bending tests, metallographical tests and fractographic analysis were performed. The steel 20 degradation factor was set in operatingconditions; it can cause accidents together with the local corrosion.
The existing systems of monitoring of transfer pipelines include control over the technical condition of linear part and equipment; assessment of technological processes impact on the environment; analysis of qualitative indicators of material flows at the entrance and exit of equipment .
The main issues of users are limited access to the data due to isolation of monitoring systems from each other and absence of specially developed algorithms of joint processing of data of a diffirent physical nature. To solve such issues, the present article provides an analysis of existing systems of monitoring of transfer pipelines, defines main controlling parameters, suggest an approach to integration of monitoring systems of architecture and data. The practical value of this article is adaptation of such solutions as Big Data and Data Mining methods while establishing data centres at enterprises of oil and gas industry to integrate, synchronize and analyse the technical information.
A big amount of oil and gas pipelines is working in complex loading conditions under the influence of active media, causing irreversible physical and chemical changes due to steel corrosion processes that lead to loss of strength and structural failure. Considered processes are dislocation and associated with an increase in the dislocation density. These processes arem\ accompanied by microplastic deformation (creep) and stress relaxation, which are accompanied by the accumulation of damage, change in plasticity and the subsequent destruction of the structure.
Estimation of resistance of offshore pipelines on land landfall of shallow-water zone of the Arctic shelf, especially when their add subaqueous permfrost surrounding require to detect invalid pipe stress. Analytic expressions are obtained for determining the stresses in the wall of the offshore pipeline at the stage of pre-project development allow us to estimate the reserves of his strength during subaqueous permfrost surrounding defrostingin the area of landfall with minimal time cost, since the numerical simulation of contact interaction between the pipe - the soil in the software package, for example, ANSYS is associated with certain difficulties for defining and setting input parameters, the determination of the initial conditions, the choiceof an appropriate model of the soil, reliably describing the behavior of material under loading and the direct simulation of the Hertzian problem.
In the coastal zone of the Arctic shelf near the coast may development sediment subaqueous permfrost surrounding. Such areas can occur freezing of sediment surrounding around offshore pipeline to transport the pumped product, even if not more negative temperatures. When freezing of the soil is cryogenic (frosty) swelling, which may lead toa change in horizontal and vertical position of the offshore pipeline with the appearance of additional longitudinal (axial) stress, affecting operational reliability of the pipeline. The proposed analytical expressions to determine the stresses in the wall of the offshor epipeline allow with sufficient for engineering calculations accuracy and with minimum time spent to evaluate the stress-strain state of the offshore pipelines at the stage of pre-project developments in freezing of subaqueous permfrost surrounding in the coastal zone of the Arctic shelf.
Results of theoretical research of transient processes in the offshore pipeline are stated at closing/opening of shut-off-and-regulating fitting elements, that also it can be applied and to definition of places of leakages of taken product in tubing strings as a result of corrosion or other their destruction. Properties of characteristics of stream in the pipelineare investigated at formation of speed and pressure wave.
Studies have shown that in the repair of corrosion damage to the pipe wall by welding, there is extensive thermal heating. During the research it was found that the depth of the zone of thermal softening depends onthe effective heat capacity and the speed of the heat source and the thickness of the metal.
Repair of corrosion damage in the pipeline wall by using manual arc welding is labor-intensive and low-productivity. Replacement of manual arc welding to mechanized flux-cored wires can significantly reduce the time spenton the renovations. However, at the current time the data on evaluation of thermal effects on the metal wall of the repaired pipeline by using welding flux-cored wires is not exist.
The increased number of trunk pipelines failures in Russia indicates the occurrence of III stage of the life cycle of pipeline transport, characterized by a sharp decrease in the reliability and the need for urgent repairs. Itrequires the introduction of advanced searching and repair methods, one of which is thewelding defects in the pipe wall cored wires.
The article presents the results of researchfor establishing dependency of adhesion and tensile strength of the insulation coating of pipelines on the ambient temperature and service life of the coating.
Monitoring of micro-vibrations of soil using coherent OTDR is one of the most promising ways to monitor activity in the buffer zone of the pipeline. An ordinary optical fiber which is laid along the pipeline is used as the sensor (for example, the “dark” fiber in a fiber optictelecommunication cable). Movement of people or vehicles, excavation works are causing a vibration of the soil which is transmitted to the cable and is detected by the monitoring system.