Spherical Storage Tank Research Articles

鋼管ブレース式球形貯槽タンクの耐震性能

A significant fire and explosion accident on spherical storage tanks for Liquefied Petroleum Gas (LPG) at Chiba prefecture in Japan were occurred due to the strong ground motion of the 2011 Great East Japan Earthquake. The braces made of steel pipe for supporting columns of a spherical tank, which was filled with water for purging air at that time, were broken by the strong seismic inertia force. Then, buckling of columns was occurred by the aftershock. To clarify the failure mechanism of the pipe braces of its supporting frame of a spherical tank, the elastic and elastic-plastic finite element analysis (FEA) was performed. From FEA results, the failure mechanism of the pipe brace was revealed as follows; (1) high stress was generated in the intersection of long and short braces due to the structural discontinuities, (2) the generated high stress was a trigger of the failure initiation of the damage of the supporting frame, (3) the breakage of the intersection of the long and short braces of the supporting frame was caused overturn of the spherical tank at the aftershock of predominant earthquake. In this paper, the fracture mechanism of the spherical storage tank was clarified for prevention of the same type accidents, and the effective reinforcement method of pipe braces of spherical tanks was proposed for securing safety.Copyright © 2015 by ASME

Numerical study of dynamic response and failure analysis of spherical storage tanks under external blast loading

The performance of energy infrastructures under extreme loading conditions, especially for blast and impact conditions, is of great importance despite the low probability for such events to occur. Due to catastrophic consequences of structural failure, it is crucial to improve the resistance of energy infrastructures against the impact of blasts. A TNT equivalent method is used to simulate a petroleum gas vapor cloud explosion when analyzing the dynamic responses of a spherical tank under external blast loads. The pressure distribution on the surface of a 1000m3 spherical storage tank is investigated. The dynamic responses of the tank, such as the distribution of effective stress, structural displacement, failure mode and energy distribution under the blast loads are studied and the simulation results reveal that the reflected pressure on the spherical tank decreases gradually from the equator to the poles of the sphere. However, the effects of the shock wave reflection are not so evident on the pillars. The structural damage of the tank subjected to blast loads included partial pillar failure from bending deformation and significant stress concentration, which can be observed in the joint between the pillar and the bottom of the spherical shell. The main reason for the remarkable deformation and structural damage is because of the initial internal energy that the tank obtained from the blast shock wave. The liquid in the tank absorbs the energy of impact loads and reduces the response at the initial stage of damage after the impact of the blast.

Ancillary services for the electrical grid by waste heat

This paper proposes a method to provide ancillary services to the electrical grid with waste heat recovery. The thermal flexibility needed to provide variable electrical output is provided by connecting the thermal source to a thermal grid and a thermal storage unit. Large capacity low heat grade thermal storages are cheaper and more readily available than large capacity electrical storage solutions, and hence thermal storage is preferable.In this paper, the dimensions of a low temperature thermal storage buffer to balance the variability of a wind- or solar plant is determined. It is calculated that a spherical storage tank of 25 m diameter and 90–130 °C would be sufficient to balance the unpredictability of a 100 MW plant of either solar- or wind energy.

Finite Element Modeling of Seismic Response of Field Fabricated Liquefied Natural Gas (LNG) Spherical Storage Vessels

All real physical structures behave dynamically when subjected to loads or displacements. This research paper, therefore, presents seismic response of field fabricated liquefied natural gas spherical storage vessels using finite element analysis. The seismic analysis procedure used represents a practical approach in quantifying the response of spherical storage vessel with its content when it is subjected to seismic loading. In the finite element method approach, six degrees of freedom per node is used for legs/column of the spherical storage tanks. Lumped mass procedure is employed to determine system mass matrix of the structure. Computer programme code is developed for the resulting matrix equation form finite element analysis of the structure using FORTRAN 90 programming language. The modeling of the seismic load utilizes the ground acceleration curve of a site. From the results of the modal analysis, the system is uncoupled thereby gives way to the application of Newmark’s method. Newmark’s method as one of the widely used time-step approach for the seismic response is applied. The developed programme coding is validated with analytical results (P > 0.5). It shows that the approach in this research work can be successfully used in determine the stability of large spherical storage vessels against seismic loadings when base acceleration spectral of the site are known. This approach gives better results than the static-force approach which gives conservative results. While the approach used in this research treats seismic loads as time event, static-force approach assumed that the full ground force due to seismic motion is applied instantaneously.

Seismic reliability of spherical containers retrofitted by means of energy dissipation devices

For the purpose of enhancing the seismic reliability of structures, external energy dissipation systems may be advantageously used. In this paper, the reliabilities of a spherical storage tank in original and updated states are assessed by means of simulation. The effect of the energy dissipation system is numerically evaluated by performing a set of nonlinear dynamic analyses on a spherical tank based on a detailed model that takes the fluid–structure interaction into account. To obtain robust estimators of the reliability, an ensemble including acceleration records with markedly different characteristics is used in the simulation study. The full reliability analysis shows that, for a typical spherical container widely used in the petrochemical industries, a reduction of the limit state probability in the order of 85% may be expected by introducing additional energy dissipation systems.

Finite Element Analysis of Von-Mises Stress Distribution in a Spherical Shell of Liquified Natural Gas (Lng) Pressure Vessels

This research work investigated the modeling of Von Mises stress in LNG Spherical Carbon Steel Storage tank using assumed displacement Finite Element analysis based on shallow shell triangular elements. Using equations of elasticity, constant thickness carbon steel spherical storage tanks were subjected to different loading conditions. This paper stresses the need for proper definition of shallow element using sector angles to obtain the shallowness. The shallow spherical triangular element has five degrees of freedom at each of its corner node, which are the essential external degrees of freedom. The assumed displacement fields of these shallow triangular elements satisfied the exact requirement of rigid body modes of motion. The FORTRAN 90 programming language was used for the programme coding to solve finite element equations resulting from the model while Von Mises stresses distribution within the spherical storage tank shell subjected to different internal pressures were determined. The results showed that the use of non-shallow elements due to improper sector angles resulted in unreliable results while real shallow elements produced results that tallied with ASME Section VIII Div 1, Part UG values.

大型球形貯槽への「SEISMIT-SP」の適用について

大型球形貯槽への「SEISMIT-SP」の適用について

球形貯槽検査用ロボットの開発

Recently new ultrasonic flaw detection system called TOFD method is utilized to externally inspect the inner and outer surfaces of weld seams on spherical storage tanks while tanks are in use. In this system, the robot mounted the sensors is not only permitted to travel along the weld seam rapidly but also required to follow the weld seam precisely. In this paper, the development of a magnetic-wheeled robot that can follow the weld seam within 5 mm based on feedback control is described. Since October 1999, this robot has been in experimental operation on an actual spherical tank. Practical introduction of this robot will shorten inspection time by about one week from the conventional 23 days, and will reduce the conventional number of inspectors required from 4 to 2-3.

Strength of welded storage tanks with shape defects during low-cycle loading

This article generalizes the numerical and experimental results of studies of the kinetics of the deformation and strength of welded storage tanks with shape defects during low-cycle loading. New relations are proposed for determining the stress-intensity factor near dents and angular sections of butt welds. The study data is used to calculate estimate the low-cycle strength of cylindrical and spherical storage tanks.

石油化学プラント機器の破壊防止法に関する検討

In order to prevent the failure of petro-chemical plants, safety assessment based on fracture mechanics is required. However, the analytical condition and the material properties are not always clear or known. For an unfavorable condition, rational assumptions with empirical background are required to be introduced. In this paper, the procedure to determine the hot start temperature and the allowable crack size for actual reactors in the lack of data is explained and the analyzed results are shown.In the case that some defects are detected during operation, the defects are usally removed and repaired with weld. However, as welding at the operating site may cause damage in some cases, repairing by grinding and smoothing is recommended in the paper. The procedure to determine the optimum shape in smoothing was proposed and is applied to an actual spherical storage tank.

Acoustic emission testing (AET) of spherical storage tanks

Acoustic emission testing (AET) of spherical storage tanks

Fatigue Reliability under Nonstationary Loads: Model Formulation

This paper develops a method for predicting the expected low‐cycle fatigue damage in structures subjected to nonstationary loading processes. The load is a filtered Gaussian random process of limited duration. The resulting strain‐response process in a given structural component determines the fatigue damage of the component. The fatigue analysis is based on a recursive definition of waiting‐time distributions for range‐pair cycles. The range‐pair waiting‐time distribution is derived from the crossing rate of the strain‐response process through strain‐range limits. The waiting‐time distributions determine the probability that a given number of range‐pair cycles will occur through the duration of the response. The damage is assumed to accumulate linearly according to the Manson‐Coffin relationship. The methodology is applied numerically to a spherical storage tank subjected to a moderate earthquake. The expected damage correlates well with the results of a Monte‐Carlo simulation, indicating that the methodology can be successfully implemented for loadings of limited duration.

Fatigue Reliability under Nonstationary Loads: Model Application

This paper develops a method for predicting the expected low‐cycle fatigue damage in structures subjected to nonstationary loading processes. The load is a filtered Gaussian random process of limited duration. The resulting strain‐response process in a given structural component determines the fatigue damage of the component. The fatigue analysis is based on a recursive definition of waiting‐time distributions for range‐pair cycles. The range‐pair waiting‐time distribution is derived from the crossing rate of the strain‐response process through strain‐range limits. The waiting‐time distributions determine the probability that a given number of range‐pair cycles will occur through the duration of the response. The damage is assumed to accumulate linearly according to the Manson‐Coffin relationship. The methodology is applied numerically to a spherical storage tank subjected to a moderate earthquake. The expected damage correlates well with the results of a Monte‐Carlo simulation, indicating that the method...

球形ガスホルダの検査ロボット

球形ガスホルダの検査ロボット

The tragedy of San Juanico—the most severe LPG disaster in history

During the early morning of Monday, 19 November 1984, one of the largest disasters in industrial history occurred in the Mexico City Area, causing the greatest rescue effort to assist population in an emergency ever undertaken. The tragic catastrophe started in at large LPG (Liquid Petroleum Gas) storage and distribution centre in San Juan Ixhuatepec, 20km north of Mexico City. The facilities, owned by the Pemex State Oil Company, consisted of six spherical storage tanks (four with a volume of 1600m and two with a volume of 2400m 2) and 48 horizontal cylindrical bullet tanks of different sizes. At the time of the disaster the storage tanks contained 11 000m 2 of a mixture of propane and butane. The inhabitants of San Juan Ixhuatepec numbered about 40 000, and a further 60 000 lived in the hills surrounding the village. The majority were poor country people living in one-storey houses constructed of concrete pillars filled in with bricks and with roofs of iron sheets. The disaster started due to LPG leakage, probably a pipe leakage or rupture due to excess pressure. A vapour cloud built up and was slowly moved by the north-east wind towards the ground-placed flare pit located in the western part of the plant. The vapour cloud was ignited around 5.40 a.m. and was followed by an extensive fire at the plant area. The first explosion was registered on the seismograph at the University of Mexico at 05 h 44 min 52s and was followed by a dozen explosions within the next hour, some of them of BLEVE type (Boiling Liquid Expanding Vapour Explosion) due to rupture of one or more storage tanks. Two of the explosions had an intensity of 0·5 on the Richter scale. Unburned and burning gas entered the houses south of the plant area and set fire to everything. Blast waves from the explosions not only destroyed a number of houses but also shifted several cylindrical tanks from their supports and added more gas to the fire. The smaller spheres and some of the cylinders exploded and fragments and even whole cylinders weighing around 30 tons, were scattered over distances ranging from a few to up to 1200m.

Damage to Oil Refineries from Major Earthquakes

Damage reports from 11 different earthquakes are summarized in tabular format for typical oil refinery structures, such as cylindrical and spherical storage tanks, tall columns and chimneys, heat exchangers, pumps, and pipes. Information included herein is limited to damage caused by direct ground-motion effects. These data reveal that the most vulnerable refinery structure is the cylindrical storage tank. Other structures, such as distilling towers and pipes, are only occasionally damaged, and rarely is this damage severe. The consequences of these rare events, however, can be very costly when they involve fires.

Calibration of spherical storage tanks

Photogrammetry seems to be the sole practical method for determining the dimensions of spherical storage tanks. This paper discusses a method using a series of single photographs.

高張力鋼製球形タンクの割れ発生状況と一考察(<小特集>大形タンクの問題点)

高張力鋼製球形タンクの割れ発生状況と一考察(<小特集>大形タンクの問題点)

Methods and equipment for measuring and preparing the edges of spherical storage tank components (survey of foreign patents)

Methods and equipment for measuring and preparing the edges of spherical storage tank components (survey of foreign patents)

Construction of spherical steel storage tanks

Construction of spherical steel storage tanks