The industry looks for new steel types, as requirements for steel strength properties in corrosion environment are becoming more stringent. Duplex stainless steels have a chance to become the most advantageous material for a number of industries. The technical interest in these alloys is due to the improvement of steel production technology, as producers found an opportunity to control nitrogen content more precisely.
The paper highlights a need to study joints weldability and corrosion resistance to hydrogen sulfide stress cracking (HSC), hydrogen
cracking (HC), intercrystalline Corrosion (ICC), knife-line attack (KLA), and pitting corrosion to assess the possibility of using duplex steels in the production of structures designed for operation in corrosion environment.
Materials and methods
To assess the possibility of using duplex steels in the manufacture of structures operated in aggressive environments, it is necessary to study the weldability of these steels and the corrosion resistance of welded joints, including against hydrogen sulfide stress cracking, hydrogen cracking, resistance to intercrystalline and knife corrosion and pitting corrosion.
weldability of duplex steels, transmission of corrosion media, welding materials, welding parameters
Since the 1950s, the gas industry has encountered pipeline accidents that could be related to the presence of hydrogen sulfide (H2S). Natural gases represent a mixture of individual gases (components), predominantly consisting of saturated hydrocarbons. At the same time, natural gas may contain up to 18–25 % of hydrogen sulfide, up to 25 % of carbon dioxide, and small volumes of nitrogen and hydrogen. The article studies conditions and impact factors, when hydrogen sulfide causes destruction of pipelines made of steels of various grades. The paper proves that steels with a duplex structure are more resistant to hydrogen cracking and hydrogen sulfide stress corrosion cracking.
Materials and methods
The study considers duplex steels with good weldability, relatively high yield and strength limits regarding satisfactory ductility and impact strength. This provides less specific metal consumption in the manufacture of structures calculated for strength due to a decrease in the sheet thickness.
duplex steels, transmission of corrosive media, hydrogen sulfide content, carbon dioxide content
The certified BIPS unit developed by “Sheshmaoil” Management Company LLC makes it possible to measure the mass and gross mass flow rate of oil in the measurement range from 0,04 t/h (1 t/day) to 4,1665 t/h (100 t/day), mass and net mass flow rate of oil, volume and volumetric flow rate of associated petroleum gas in the oil and gas-water mixture, reduced to standard conditions in the measurement range from 12,5 m3/h (300 m3/day) to 208,3 m3/h (5 000 m3/day) with the content of associated petroleum gas in dehydrated oil not more than 50 m3/t under standard conditions. The values measured with the BIPS do not exceed the rates and the limits of permissible errors. The analysis of measurement results
Materials and methods
The relative errors in measuring fluid and oil mass flow, as well as those of air flow were determined on a certified test bench. A method of measurements by the BIPS unit based on the accumulation of a watergas-oil mixture in a calibrated measuring tank has been developed, certified and tested.
gas oil ratio measurement, flow rate, water cut, free and dissolved gas, measurement error
The formation of organic deposits is one of the most common problems in the production and transportation of well products. In the fight against this complication, many modern methods are used, one of them is the “Controlled Layer” technology. One of the most important values considered when determining the technological efficiency of this technology is the thermal conductivity of organic deposits. In this work, laboratory studies were carried out to determine the nature and degree of change in the thermal conductivity of these deposits from the water content of the studied emulsion. Analyzing the results of laboratory studies, it becomes obvious that the high-water content of the transported emulsion increases the
thermal conductivity of deposits, which has an exceptionally negative impact on the technological efficiency of the technology under consideration.
Materials and methods
Materials: reservoir fluid samples from the target technological object, the “Cold Finger” installation, the Rheotest RN 4.1 rotary viscometer. Methods: research on the “Cold Finger” installation, the authors method for determining the thermal conductivity of organic deposits.
“controlled layer”, asphalt-resin-paraffin deposits, thermal conductivity, intensity, water content
At the stage of assessing the technical condition of main pipelines, the stress concentration factor for stresses occurring in the pipe wall in the area of the identified corrosion defect is taken as a deterministic value. The models used to calculate this factor contain such a parameter as the pipe wall thickness, which is a random variable and has individual distributions even for pipes of the same range. Due to the presence of a functional relationship with the thickness of the pipe wall, the values of the stress concentration factor also obey distributions, the type of which depends on the statistical spread of the values of the pipe wall thickness. The necessity of taking into account the stress concentration factor in the calculation models as a random variable is justified by the example of assessing the strength reliability and the level of risk of linear sections of the main oil pipeline complicated by a corrosion defect.
Material and methods
The pipe wall thickness was measured using an ultrasonic thickness gauge of the DM2 model manufactured by “Krautkrämer GmbH & CO” (Germany). The processing of the measurement results and the calculation of the values of the reliability indicators are based on the methods of nonparametric statistics and the theory of reliability. The stress concentration coefficient is calculated on the basis of the
main oil pipeline, linear part, corrosion defect, stress concentration factor, strength reliability, failure probability
Pipeline transport is the main method of transportation of hydrocarbons. Based on the analysis of field data, it was determined that the intercleaning period of pipelines is associated with the time of year and reaches its peak in the spring. In the laboratory of “Oilfield chemistry” of the REC GiRNGM PNRPU, using the “Cold finger” installation, laboratory studies were carried out to determine the kinetic parameters of the formation of organic deposits in different months of the year. Analysis of the results of laboratory studies allows us to note that these parameters are nonlinear functions of temperature, but it is not possible to predict changes in the value of the MOS only on the basis of laboratory studies, which is why the authors of the article proposed the introduction of the value of the relative MOS. The introduction of this parameter will make it possible to predict the nature and extent of changes in the MOS of the pipeline on the basis of laboratory studies and using pipeline modeling in hydrodynamic simulators.
Material and methods
Analysis of commercial and theoretical information, conducting laboratory studies and modeling the process of paraffin formation.
asphalt-resin-paraffin deposits, statistics of treatment measures, equipment of the “Cold finger”, inter-treatment period, hydrodynamic modeling, linear oil pipeline
The strength reliability of linear sections of main pipelines is evaluated based on indicators that include the probability of failure and the safety coefficient. Probabilistic models used for calculating these indicators contain a number of parameters that are taken as random variables when calculating them. Patterns of distribution and dispersion limits of such parameters have a significant impact on the results of calculating reliability indicators. One of the parameters that is included in probabilistic models as a deterministic value, but actually has a random nature, is the thickness of the pipe wall. Based on the examples of assessing the strength reliability of sections of the main oil pipeline, the necessity of taking this parameter into account in the calculation models as a random variable is justified.
Material and methods
Measurements of the actual values of the pipe wall thickness were performed using an ultrasonic thickness gauge of the DM2 model manufactured by “Kräutkramer GmbH & CO” (Germany), processing of the measurement results and calculation of the failure probability values were performed based on the methods of nonparametric statistics and reliability theory.
main oil pipeline, linear part, reliability, probability of failure, risk level
In this paper the problem of placement the shut-off valves along the length of the pipeline is considered as a multicriterion one, taking into account such factors as the possible volume of spill oil, category of pipeline, the maximum distance between shut-off valves and possible economic losses in the event of a pipeline failure, with appropriate arrangement. As an example, we considered a pipeline section with several options for placing stop valves and selected the best one according to the proposed method.
Materials and methods
Research materials: regulatory and technical documentation in the field of pipeline design, existing coordinates of the placement of shut-off valves on the pipeline section. Research methods: Data Envelopment Analysis (DEA) method to
estimation of effectiveness structural elements placing on the oil trunk pipeline. Method of economic assessment of possible damage from pipeline breakage.
oil, shut-off valves, minimization of environmental impact, reduce environmental risks, economic damage to the environment
The article explores the methods of natural gas utilization from the emptied sections of pipelines during scheduled preventive maintenance. In order to reduce the amount of greenhouse gas emissions into the atmosphere, a
technological scheme has been developed for the utilization of natural gas using a booster compressor station by means of a successive pressure reduction.
Materials and methods
Methods of natural gas utilization.
cenomanian deposit, booster compressor station, complex gas treatment unit, gas utilization, mobile compressor unit, scheduled preventive maintenance
The paper presents the results of monitoring the safety factor of linear sections in different years of operation of the main gas pipeline. The actual values of the reserve coefficient are calculated taking into account the laws of distribution of excess internal pressure and temperature drop in the studied areas, which are individual for each year of operation, as well as the random nature of the yield strength of the pipe material. Based on the obtained results of monitoring the values of the reserve coefficient, the actual level of reliability is estimated and the safety class of the linear section sections is justified for different periods of time at the stage of operation of the main gas pipeline. The necessity of taking into account the random variation of the safety factor values established as a result of monitoring within the same sections for different periods of operation of the main gas pipeline when planning the strategy of its operation, maintenance and repair is justified.
Materials and methods
The design values of the reserve coefficient for sections of the main gas pipeline are calculated in accordance with the requirements of SNiP 2.05.0685* (Main pipelines). Experimental studies of the mechanical characteristics of the material of pipes made of steel 17G1C, performed in accordance with the requirements of GOST 1497-84. (Metals. Tensile testing methods). Regularities of changes in the yield strength of pipe metal are obtained based on processing of experimental results using nonparametric statistics. The actual values of the safety margin coefficient and the current level of reliability of sections of the main gas pipeline were estimated according to the STO of PJSC Gazprom 2-2.3-184-2007.
monitoring, main gas pipeline, linear section, safety factor
The temperature drop is one of the parameters that is taken into account when calculating the strength and stability of the main oil pipeline in accordance with the requirements of the industry regulatory standard (SNiP). The acceptable values of the temperature drop are determined as the result of calculation for the accepted pipeline design based on the limit state of the pipeline, which is determined in accordance with industry standards. However, at the operation stage, the absolute values of this parameter may not correspond to the design values, since seasonal and daily temperature fluctuations, thermal interaction of the underground oil trunk pipeline and the ground lead to changes in the temperature field around the pipe along the pipeline route. As a result, there are differences between the standard values of the temperature drop and the actual values at which the pipeline was filled with soil during construction and its subsequent operation. For this reason, longitudinal and transverse displacements and stress increase, which causes the spatial positions of the sections of the linear part to deviate from the design and may lead to loss of bearing capacity and reliability of the pipeline, as well as the risk of accidents. The paper presents the results of a study of changes in the reliability of sections of the linear part and the level of risk that occurs during the operation of the main oil pipeline, depending on different values of the temperature difference in the pipe wall.
main oil pipeline, linear part, temperature drop, reliability, probability of failure, risk
The paper presents the results of calculating the stresses in the wall of an underground pipeline loaded with pipeline solid 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 pipeline solid 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.
Assessment of the s trength reliability of main pipelines sections is based on the integration into the calculation models of reliability indicators of probability patterns for the e xternal load acting on the examined section of the main pipelines linear part, and the s trength characteristics of the pipe m aterial used at the construction stage of this section. The experience accumulated to date in calculating reliability indicators allows us to conclude that these patterns are actually individual and specific for any part of the main pipeline linear part. Moreover, even within the same section, individual probabilistic patterns for the parameters of the e xternal load and ultimate stresses are changed during the lif e of the main pipeline.
The paper assesses the impact of changes in the statistical characteristics of the distribution of the yield strength of pipe steels on the s trength reliability of sections of main pipelines.
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 (σÒ) 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.