Vertical Steel Tanks Research Articles

Development of Measures to Improve Occupational Safety during Operation of Reservoirs in Spring

Introduction . The paper considers the problem of ice formation on the spray ring of vertical steel tanks (VST) in spring, which threatens the safety of operating personnel when carrying out technological operations. The necessity of introduction of means of protection against ice is emphasized, which will make it possible to release commercial operators from performance of high risk operations of ice clearing from dry pipelines. Problem Statement . The task of the research is to substantiate the use of possible ways of icing control on the tank spray ring. Theoretical Part . As the basic information, the modern methods of de-icing used in mechanical engineering, oil industry and construction are presented. Conclusions . As a result, the work proposes options for the use of means to fight against icing, through which the overall level of safety in the tank farm will increase.

Edge effect of the tank wall-bottom joint on service reliability of vertical steel tank

The paper presents the analysis of the edge effect in the wall bending of a vertical steel tank RVS-20000 using a comparison between the results obtained by using the bending theory and membrane theory. It is shown that the condition of the wall-bottom joint strength is satisfied in both cases.The stresses obtained according to the bending theory with regard to multiplying safety factor, exceed the maximum stresses by 11.1 % obtained by using the membrane theory with account for the edge effect. This makes it possible to use the membrane theory equations in calculating the wall thickness, which excludes complex calculations of the bending theory. Unlike the membrane theory, the membrane theory provides the stress and strain calculation of the T-junction. The results obtained indicate that the service reliability of the wall-bottom joint is primarily determined by the preparation quality of the tank base, welding quality of the T-junction (including negative temperatures) and the methods of their flaw detection on the construction site.

Evaluation of Explosive Safety Parameters for Stationary Roofs of Vertical Steel Tanks

The article is devoted to a current problem of the need to increase the explosive safety of tanks. The paper analyzes the causes of explosions in tanks. Constructive solutions of existing stationary tank roofs are analyzed, including with an easily removable sheathing. The required areas of loss of containment of the tank roof are calculated depending on the type of flammable liquid. The dependence of the level of filling the oil product in the tank on the excess pressure during the explosion has been determined. Criteria and requirements have been developed for fixed roofs with easily removable sheathing.

Исследование процесса остывания битума в надземном резервуаре с целью разработки технологически и энергетически эффективных методов поддержания его температуры

The article is devoted to the study of the process of bitumen BND-60/90 cooling in an elevated vertical steel tank. Attention to this issue is dictated by the fact, that the specific properties of the product increasing viscosity and tendency to solidification during cooling — create difficulties in its operational turnover for the operators, and storage at high temperature leads to deterioration of the commodity properties. The relevance of the study comes from the need to find an energy-efficient solution for enterprises which accept, store and promptly dispense bitumen on an industrial scale. The work was conducted in order to explore the possibility of reducing energy consumption, while heating the product, by optimizing the design of the heater. The object of the research was an insulated tank RVS-3000 with a fixed roof, the prototype of the same volume of which was built by Himstalcon-Engineering LLC in Kaluga. It is assumed, that this tank was filled with bitumen heated to a temperature of 160⁰С. In this work the distribution of the temperature field, as well as the field of velocity of bitumen movement over the volume of the tank, were obtained. This allowed us to formulate preliminary conclusions about promising directions for the development of technologically and energetically efficient methods of maintaining its temperature.

Simulation of the stress-strain state of a cylindrical tank under the action of forced oscillations

The paper considers the classification of steel cylindrical tanks failure from the action of seismic loads. Features of static calculation of tanks were revealed. Physical and mechanical properties of the material and geometric parameters of the vertical tank were determined. A full-size finite element model of a filled vertical steel tank has been developed. The calculation of the filled vertical steel tank was performed. The values of frequencies and periods of natural oscillations were obtained. Finite element method that was implemented in LIRA-multifunctional software package allows to design and calculate the structures for various purposes.

АНАЛИЗ ДЕФОРМАЦИЙ И НАПРЯЖЕНИЙ ОБОЛОЧКИ ВЕРТИКАЛЬНЫХ СТАЛЬНЫХ РЕЗЕРВУАРОВ ПО ДАННЫМ ЛАЗЕРНОГО СКАНИРОВАНИЯ

The article considers a new technology of measurements of vertical steel tanks (ground-based laser scanning), which delivers a huge volume of unstructured information. There has been carried out a review of existing methods for solving tasks of tank walls' defomations determinations on laser reflec-tion point cloud. It is noted that the accuracy of laser scanning and scans' stitching is sufficient for tank walls' defomations determinations. The existing methods are implemented basically through building irregular triangular surfaces of tank shell on which then surface profiles are built manually or semi-automatically and the defomations are determined and compared to tolerance values. The au-thors suggest a method and algorithm for processing laser reflection point cloud, which by means of several infiltrations by height, radius tolerance and inclinations and interpolation by collocation meth-od is drawn to a rectangular topologically equivalent grid. These allow by several orders to decrease the information volume stored in the database, and regular grid model structure allows to apply numer-ical calculation method for calculating strains occurring in the tank walls. The strains are determined on semi-momentless theory for cylinder shell calculation. The method and algorithm are implemented in geodetic subsystem of automatic system of technical maintenance and repairs of equipment on the oil processing plant. The suggested method will allow in the future to move from normative assess-ment of technical tank state to the assessment on actual strains, which gives objective assessment of tank state for making substantiated decision on the prolongation of its exploitation, current mainte-nance and repair.

Investigation of parameters of leakage of toxic and explosive substances and gases under the action of high pressure from tanks of the special purpose during

Tanks for the storage of oil products and toxic substances in warehouses are the main ones. They can be in the form of separate tanks or a group of tanks. The most widespread are vertical steel tanks with a stationary roof that a placed in open areas. The tanks heat up, and the intensity of evaporation of the oil product increases in case of fire. If there is a permanent roof, the pressure in the tank will increase. If the capacity of the breathing valves is less than the intensity of evaporation then there is a risk of explosion. Explosions in the tank often lead to the separation of the bottom, and the side cylindrical surface and the roof fly away instantly, spilling oil on neighboring tanks and the territory of the tank’s park. Then the combustion area increases intensively. The destruction of the integrity of the tank, due to the separation of the bottom, contributes to temperature and power stresses, the value of which increases with increasing temperature of their heating and increasing pressure, respectively. The values of temperature stresses are added to the power stresses caused by pressure, and when the critical value is reached, destruction occurs.
 In the article by the method of mathematical modeling using the laws of thermodynamics and mechanics of liquids and gases, analytical dependences for research of parameters of leakage of toxic substances and gases at action of high pressure from capacities at their storage are received. Saint-Venant’s principle was used to model the gas flow rate process. The dependence of the duration of gas leakage from special purpose tanks at the change of the area of the emergency hole and the pressure drop is obtained. The obtained results allow determining the velocity and mass flow rate of the gas depending on the area of the hole, the time flow, and the difference of pressure. Therefore, the task of research the emergency situations of engineering cylindrical tanks under the influence of temperature and pressure, which leads to the spillage of toxic substances and gassiness is actual. The researches results are presented graphically.

Mine surveying technique and steel storage tank base deformation removal

Introduction. Vertical steel tanks are extensively used in oil fields to hold crude oil and other liquids. Their construction requires continuous surveying control. However, measurement procedures, data processing, and deviations and documentation correction are not universal and cannot be applied for tanks with a capacity of less than 3000 m3. Moreover, the process of correcting the detected bottom irregularities is poorly substantiated and intuitive. Research objective is to improve the as-built survey accuracy and reliability of the low-capacity steel tank bottom, substantiate the minimum height of its irregularities, increase the objectivity and productivity of measurement processing, develop an unambiguous method for time-predictable correction of bottom irregularities, and substantiate the optimal contents of its relief’s as-built scheme. Methods of research. Geometric leveling for the bottom profile survey failed to provide adequate accuracy and was therefore replaced by the method of trigonometric leveling. A method has been developed for determining the deviations of the existent tank bottom profile from the design position by means of algebraic actions with surfaces of a topographic order. The accuracy of determining the smallest height of bottom irregularities has been estimated under the tacheometric survey. A method has been proposed for controlling the correction of tank bottom irregularities based on evaluation calculations of bottom deformations by the finite element method. Research results. All the development results are exemplified by a specific production example. It was found that for a full completion of work, two iterations of tank bottom irregularities correction are enough. Methods of optimal design for the facility’s as-built schemes are presented. Conclusions. A simple, accurate, low-cost, productive, and time-predictable method of mine surveying, mathematical processing and correction of deviations in the tank bottom profile has been developed. This technique reduces the construction period and increases the operating time of the facility.

Dynamic Measurements of Tank Wall Deformations as a New Method for Assessing its Technical Condition

The paper proposes a new approach to assessing the residual resource of the wall of a vertical steel tank by the criterion of low-cycle loading, taking into account its actual deformations. The method is based on the principle of measuring the difference in the power of the luminous flux at the ends of the light tube (light guide) when it is bent. An experiment was carried out using an optical pair (LED and photodiode) and an optical fiber. For this purpose, templates with known radii of curvature were prepared, a prototype of an Arduino-based device was developed and an optical fiber was manufactured, which was subsequently fixed on the wall of a two-hundred-liter metal barrel. As a result of the experiments, a formula was obtained for determining the curvature of the wall depending on the readings of the sensor. The sensitivity of the proposed method is estimated. An algorithm for determining the number of cycles before the formation of fatigue cracks is proposed, taking into account the actual values of the wall deflection.

Fire resistance of a vertical oil tank exposed to pool-fire heat radiation after high-velocity projectile impact

Due to the complex effects of combined loadings on complete steel structures, the combined effects of high-velocity projectile impact and heat radiation due to a pool-fire on a vertical Q345 steel tank have not been generally considered. In this study, a consecutive coupling approach is established. The combined effects of projectile perforation and heat radiation on the failure modes and fire resistance of a vertical steel tank are investigated. Additionally, the effects of the projectile size, projectile shape, and separation distance are analyzed. The results indicate that compared with a fixed-roof tank without impact, the perforation results in stress concentrations in the plastic deformation zone. The stress level of the perforated tank is higher, and the fire resistance of the perforated tank is lower. Additionally, as the perforation size increases, the stress level triggering the thermal buckling of the perforated tank decreases outside of the plastic deformation zone. Additionally, the fire resistance decreases. Moreover, as the separation distance decreases, the stress level of the cylindrical shell increases. The fire resistance of the perforated tank decreases dramatically. By understanding the failure mode, this study is able to suggest fire and explosion protection measures in petrochemical industries to decrease or eliminate the domino effect risk and incident damage. Additionally, the fire resistance data can help improve guidelines and understanding for fire and rescue services, which would undoubtedly play a vital part in emergency response and rescue, and enhance the process safety level overall.

Automatic mass meter, increasing the accuracy of calculating the gross weight of oil in vertical steel tanks

Improving the efficiency of operation of trunk pipelines. However, to assess the activities carried out, accurate and reliable information about the amount of the pumped and stored product is required. Existing methods for measuring the amount of liquid and methods of using capacity measures lead to large errors in calculations. Measurement and tampering with the turnover reporting process depends on the “human factor” and the prerequisites for introducing measurement and tampering into the turnover reporting process. In operation, an automatic system for measuring pressure and temperature by product layers based on the hydrostatic principle of operation, which allows calculating the gross mass of oil. Also, the paper analyzes methods for increasing the accuracy of calibration tables obtained in the process of tank calibration. The proposed system improves the measurement accuracy, productivity and operational efficiency of tank farms.

Determination of crack resistance of a tank with elliptical crack

The occurrence of crack-like defects is a common phenomenon in the operation of vertical steel tanks (VST). Such defects can occur both at the beginning of the operation of the tanks, which may be associated with a violation of the manufacture conditions or the installation procedures of the tank elements and during operation. Over time, such defects increase significantly and turn into cracks. Existing regulations prohibit the operation of VST with cracks. At the same time, the organization that operates the tank does not always have the opportunity to perform repairs immediately. There are cases of trouble-free operation of tanks with non-through surface cracks at the stage of sustainable growth, which are confirmed by model calculations are known from practical experience. The analysis of crack resistance of the VST-5000 tank with a semi-elliptical crack under the action of hydrostatic pressure is carried out in the work. The level of filling the tank with petroleum products is 95% of its height. The semi-elliptical crack is located on outside surface of the wall panel in lower row of cladding. Determination of crack resistance of a tank with a crack is performed on the basis of stress intensity factors (SIF). Direct and energy methods were used to SIF calculation. Determination of the stress-strain state is performed on the basis of the semi-analytical finite element method (SFEM). The SIF distribution along the crack front obtained using SFEM by both direct and energy methods almost coincides and agrees well with the values of SIF calculated by the direct method when using three-dimensional FEM. The obtained values of SIF differ along the crack front by 50%: the minimum value of SIF acquires at the point of the front, which is located on the outer surface of the tank, the maximum one - at the point of the front inside the wall that is furthest from the outer surface. The obtained results show the quite uneven SIF distribution along the crack front, so that the calculation of such problems requires the spatial setting of problem.

The influence of pressure changes on the integrity of tanks for storage of petroleum products and toxic substances

Tanks for the storage of oil products and toxic substances in warehouses are the main ones. They can be in the form of separate tanks or a group of tanks. The most widespread are vertical steel tanks with a stationary roof that a placed in open areas. The tanks heat up, and the intensity of evaporation of the oil product increases in case of fire. If there is a permanent roof, the pressure in the tank will increase. If the capacity of the breathing valves is less than the intensity of evaporation then there is a risk of explosion. Explosions in the tank often lead to the separation of the bottom, and the side cylindrical surface and the roof fly away instantly, spilling oil on neighboring tanks and the territory of the tank’s park. Then the combustion area increases intensively. The destruction of the integrity of the tank, due to the separation of the bottom, contributes to temperature and power stresses, the value of which increases with increasing temperature of their heating and increasing pressure, respectively. The values of temperature stresses are added to the power stresses caused by pressure, and when the critical value is reached, destruction occurs.
 We investigated the stress-strain state of a steel vertical tank for the storage of oil products and toxic substances. The analysis of the reasons for the occurrence of admissible pressure in the tank, which is the reason for the loss of its integrity, is carried out. Using the differential equation of a closed cylindrical shell, which is under the action of internal pressure, analytical expressions are obtained to find deformations and stresses in the side cylindrical surface and bottom. Were calculated axial and annular stresses for the tank of RVS-900. Based on the basic relations of the theory of elasticity of thin plates and shells analytical expressions of the stress-strain state of the cylindrical tanks are obtained for conditions for changing of pressure on their structural elements. It is shown that the greatest values of axial stresses are obtained on the surface of the connection of the cylindrical surface with the bottom. The researches results are presented graphically.

Evaluation of the Thermal Radiation Intensity During a Fire in the Oil Tank Farm Dike

Petroleum product storage facilities are explosion and fire hazard systems. The occurrence of an accident with oil spillage followed by a fire creates the danger of exposure of humans and the environment to thermal radiation. The most typical emergency is a fire of spills in the dike. This paper proposes a technical solution aimed at reducing the fire and explosion hazard for oil tanks. The thermal radiation intensity during a fire of spills in the dike has been calculated. The need to protect the oil storage tank farm with a fence wall with a wave deflector baffle has been proposed and mathematically justified. Along with reducing the likelihood of oil spills at the destruction of a vertical steel tank, this appliance will reduce the environmental consequences of a man-made accident.

Welded joint permissible defects influence on the resource of a vertical steel tank under low-cycle loading

This paper is devoted to the VST determining the residual life issues by the shell welds low-cycle fatigue criterion with permissible defects, taking into account a typical stress concentrator, which has not been fully studied. The fatigue tests results analysis for materials made of low-alloy steel, taking into account welded joints, is given. The Ansys software package has built a model and calculated the stress-strain a vertical steel tank lower belt state for storing oil and oil products VST 20000 with a branch pipe. It is shown that the VST design most dangerous point is in the branch pipe upper part. The maximum stresses and stress amplitudes were obtained in the stub pipe zone and the wornom seam. The cycles to failure performed calculations number showed that the lower VST belt without welded joints wall area withstands 2.4 times more loading cycles than the area with a welded seam and 9.3 times more than the dangerous point in the nozzle stub area.

Stability of fire barriers in tank farms in case of destruction of vertical tanks

The issue of raising the level of safety of people, lands and property from potential threats in emergency situations in oil and gas storage and processing sites is particular concern to all levels of authority in countries, whether they are legal or executive authority. Study of the statistical data of incidents and fires at these equipment showed that the most negative effects for the damage to the company’s personnel, the population and the environment occurred during the quasi-instantaneous destruction of the vertical steel tank. The distinguishing features of such an accident are the complete loss of the integrity of the vertical oil tank hull and the release of all the liquid stored in the tank in the form of a powerful flow (breakout wave), which has a great destructive power, to the adjacent territory within a short term of time. The most important measures to reduce oil and petroleum products leakage in tank farms are reinforced earth dams and closed walls made of materials that are vulnerable to heat (important in the case of fire), Which led to many unsolvable cases. Recently, vertical steel tank with double walls of the “glass in a glass “type have been used in some oil tanks, in practice, they have not found wide application, which is due, first of all, it needs to allocate a significant territory for their arrangement, and its high cost.

Современные методы сборки корпусов вертикальных стальных резервуаров и методы контроля ее выполнения

Современные методы сборки корпусов вертикальных стальных резервуаров и методы контроля ее выполнения

Моделювання теплового впливу пожежі в резервуарі з нафтопродуктом на сусідній резервуар

The forecasting of the consequences of emergencies caused by the fire of a vertical steel tank with oil product in the tank group is considered. Due to the thermal impact of the fire on the next tanks, there is a threat of cascading fire.. Assumptions based on the model of heating the tank shell under the thermal influence of a fire in the adjacent tank are substantiated. This model is a differential equation that describes the process of heat transfer inside the tank shell, with boundary conditions on the outer and inner surfaces of the shell. These boundary conditions describe the heat exchange of the shell surfaces with the torch, the environment and the vapor-air mixture in the gas space of the tank. The model takes into account heat exchange by radiation and convection. An estimation of the value of the mutual irradiation coefficient with a torch for an arbitrary point on the tank shell is obtained. It is shown that after transition to dimensionless coordinates the value of the irradiation coefficient for all tanks with a capacity of up to 20000 m3 depends only on the type of liquid – flammable or highly flammable. An estimation of the convective heat transfer coefficient under free convection conditions with ambient air for the outer surface of the tank shell and with a vapor-air mixture in the gas space of the tank for the inner shell surface is obtained. The estimation is obtained by using the methods of similarity theory. Numerical solution of the heat balance equation for the tank shell allows finding the temperature distribution on the shell at an arbitrary time. This allows determining the area on the tank shell that needs cooling and determining the time limit of its onset. It is shown that within 5 minutes after the start of the fire, the temperature of the part of the adjacent tank shell that facing the fire reaches dangerous values.

Влияние осадка остаточных топлив на напряженно-деформированное состояние вертикального стального резервуара

The article studies the formation of the total sediment by the incompatibility of residual fuels and oil products, analyzes and calculates the stress-strain state of the tank taking into account oil products and sediment. The studies examined the influence of temperature fields on the sedimentation of a mixture of residual fuels caused by the incompatibility of these components. Temperatures of a stored product, namely residual fuel RMK-700, and ambient temperatures are taken into account when modelling in ANSYS product. Effects that oil product has separately and oil product with bottom sediments have on a stress-stain state are compared. Laboratory tests were performed to accurately measure density depending on various temperatures. By means of finite element method a stress-stain state of a vertical steel tank RVS-20000 is examined, the calculations showed that the maximum stresses are located in zones of the weld seam and in the places of installation of the receiving-distributing branch pipe and manhole. In these areas bottom sediment and temperature difference influence the stress-stain state greatly, with the stresses becoming even higher as the wall gets thinner.

Thermal post-buckling behavior of oil storage tanks under a nearby fire

This paper reports research on the thermal buckling and post-buckling of vertical steel tanks under heat induced by a nearby burning tank. A two-layer solid flame model is adopted and a heat transfer analysis is carried out to compute temperatures in the target tank. The temperatures are used as input in the structural analysis based on a geometrically nonlinear analysis and temperature-dependent properties of steel. The structural problem is solved by a finite element analysis to trace the pre- and post-critical equilibrium path. The lower critical temperature is detected and subsequent instabilities are identified until the temperature reaches the maximum value that can be transferred for the specific fuel burning. The post-buckling response is investigated to account for wind effects, separation between tanks, and fluid stored in the target tank. The ratio between first critical temperature and the final temperature at which the process reaches a thermal steady state, is computed in each case.