Large Oil Storage Research Articles

Elastic-Plastic, Large Deformation Finite Element Analysis of Uplifted Shell-to-Annular Joint in a Large Aboveground Oil Storage Tank

Elastic-Plastic, Large Deformation Finite Element Analysis of Uplifted Shell-to-Annular Joint in a Large Aboveground Oil Storage Tank

Buckling Characteristics of Large Aboveground Oil Storage Tanks under External Liquid Pressure

Buckling Characteristics of Large Aboveground Oil Storage Tanks under External Liquid Pressure

Buckling Characteristics of Large Aboveground Oil Storage Tanks under both Internal and External Liquid Pressure

Buckling Characteristics of Large Aboveground Oil Storage Tanks under both Internal and External Liquid Pressure

Overview of Problems and Solutions in Fire Protection Engineering of Wind Turbines

The wind energy industry is one of today’s leading industries in the renewable energy sector, providing an affordable and sustainable energy solution. However, the wind industry faces a number of challenges, one of which is fire and that can cast a shadow on its green credentials. The three elements of the fire triangle, fuel (oil and polymers), oxygen (wind) and ignition (electric, mechanical and lighting) are represent and confined to the small and closed compartment of the turbine nacelle. Moreover, once ignition occurs in a turbine, the chances of externally fighting the fire are very slim due to the height of the nacelle and the often remote location of the wind farm. Instances of reports about fires in wind farms are increasing, yet the true extent of the impact of fires on the energy industry on a global scale is impossible to assess. Sources of information are incomplete, biased, or contain non-publically available data. The poor statistical records of wind turbine fires are a main cause of concern and hinder any research effort in this field. This paper aims to summarise the current state of knowledge in this area by presenting a review of the few sources which are available, in order to quantify and understand the fire problem in wind energy. We have found that fire is the second leading cause of catastrophic accidents in wind turbines (after blade failure) and accounts for 10 to 30% of the reported turbine accidents of any year since 1980’s. In 90% of the cases, the fire leads to a total loss of the wind turbine, or at least a downtime that results in the accumulation of economic losses. The main causes of fire ignition in wind turbines are (in decreasing order of importance): lighting strike, electrical malfunction, mechanical malfunction, and maintenance. Due to the many flammable materials used in a wind turbine (eg. fiberglass reinforced polymers, foam insulation, cables) and the large oil storage used for lubrication of mechanical components, the fuel load in a turbine nacelle is commonly very large. The paper finishes with an overview of the passive and active protection options and the economics (costs, revenue and insurance) of wind turbines to put in context the value of a loss turbine compared to the cost and options of fire protection. We hope that this paper will encourage the scientific community to pursue a proper understanding of the problem and its scale, allowing the development of the most appropriate fire protection engineering solutions.

A New Method to Prevent Elephant Foot Buckling on Tank Wall of Large Oil Storage Tanks

A New Method to Prevent Elephant Foot Buckling on Tank Wall of Large Oil Storage Tanks

FOAM CONCENTRATES APPLICATION RATE AND THEIR FLOW RATES: AN OVERVIEW ON FLOATING ROOF TANK FIRE EXTINGUISHMENT

The basic characteristics of foam concentrates appl ication rate and their flow rates for fire fighting to extinguish tank fire are briefed. It is pointed out that the present fire fighting systems of large scale crude oil storage depots canno t meet the need to extinguish tank fires. In petroleum refinery, various hydrocarbons, both liquid and gaseous are handled. These hydroca rbons are flammable and explosive in nature and volatile to varying degrees depending upon their operating conditions. As the process operations are carried out at elevated temperatures and pressures, they of fer high risk of fire and explosions and therefore it is imperative that proper safety precautions are taken in carrying out operations sa fely and prevent incidence of fires and explosions. This paper covers the application rate and flow rates of foam onto a fire is normally expressed as the amount of foam soluti on, in litres per minute, to be applied to every square metre of the total area to be covered with foam.

Fire Risk Forecast and Early Warning Technology for Large Oil and Gas Storage & Transport Tank Areas

According to the characteristics of the storage and transportation working functions in large oil and gas storage tank areas, based on the analysis of equipments leakages, fires, explosion and other disaster scenes and accidents evolution model in the tank areas, the effect factors of the tanks area fire risk were studied. Combined with the analysis of key equipments and process fittings failure probabilities and tank fire-fighting equipments effectiveness, the fire and explosion accidents forecast analysis methods based on the dynamic monitoring technology were put forward. Through the analysis of the critical temperature, pressure, liquid level, gas concentration and other state parameters of the oil and gas storage tank equipments failure, using the advanced information technologies (GIS geographic information system, RS remote sensing and telemetry systems, etc.) and remote singles monitor technologies, the status parameters of dangerous materials and process equipments can be carried out with real time measurement and monitoring.

Deformation Characteristic Evaluation of Large Oil Storage Tanks under the Planar Inclined Foundation

Oil storage tank plays an important role in modern oil industry. The development of large-scale oil storage tanks has resulted in the complexity of stress distribution and deformation situation of tank wall and tank bottom. Especially in soft foundations, the tank structure is susceptible to various types of settlement deflections. The most common type is planar inclined foundation. In this paper, the finite element model of large-scale oil storage tank was built according to the pattern of design and the deformation characteristic and stress distribution of large storage tank under the planar inclined foundation was obtained. Considering the floating roof, the ultimate value of large storage tank under the planar inclined foundation is determined.

Acoustic Emission Based Tank Bottom Floor Corrosion Detection

The tank bottom floor is a crucial component of large oil storage tanks, and its status has a pivotal impact on the integrity of the entire tank. Acoustic Emission (AE) monitoring is an advanced, in-service, nondestructive testing method internationally recognized to be capable of assessing the tank bottom floor without the necessity of prior tank cleaning. In this paper, the principle of Time Difference of Arrival (TDOA) is illustrated, and the efficiency of piezoelectric AE sensors is verified through a field experiment. The authors then investigate Mach-Zehnder interferometerbased AE sensors with a view to using optical fiber sensors as a substitute for acoustic emission detecting. The results of the experiment indicate that optical fiber AE sensors based on the Mach-Zehnder interferometer can be used as transducers sensitive to acoustic events, so they can serve as indicators of the imminent failure of a structure. In addition, some suggestions are put forward regarding forthcoming actual application.

An analytical formula for elastic–plastic instability of large oil storage tanks

Assuming axisymmetric buckling and according to the adjacent equilibrium criterion, a buckling critical stress formula of a perfect tank wall is first obtained through analysis of elastic–plastic buckling carried out by J2 plastic flow theory. Furthermore, combining the current tank seismic design standards and the results obtained in this paper, a new critical buckling stress formula of the tank wall is derived after correction for material plasticity by introducing a plasticity influence coefficient. Comparisons between the results obtained and those from the relevant formulas in the design standards of America, Japan, China and Europe are also performed. Our research shows that under interaction of high hydraulic and axial compression, the material properties of the tank wall change rapidly, and the buckling strength of the tank wall also decreases rapidly. The relation between the tank wall buckling critical stress and the hydraulic pressure is similar to Rotter's semi-empirical formula. The results presented in this paper can provide technical support in further protection of large oil storage tanks.

Method Study for Finite Element Modeling of Large Oil Storage Tanks

This article, basing on the field test stress of an oil-storage tank in the site, investigated finite element modeling method for large oil storage tanks. To study the effects of contact conditions among the tank wall, bottom plate and the foundation, the soil of the foundation, and holing on the tank stress, six different finite element models were built by ANSYS finite element analysis software. The stresses in the tank were calculated under the gravity load and the water pressure. Results of the six models have been compared with the field test values. It was obtained for the stress distribution in the tank wall, bottom plate, and big horn weld and around the manhole from which the influence scope and extent to the tank was investigated. It shows that the calculated stresses have a good agreement with measurement. The plane model has enough precision for the tank stress analysis. The contact conditions and soil affect on the stress in the scope with 0.2H and 0.24H (the height of the tank), and holing affects the adjacent area with 2D (the diameter of the manhole).

Study of Fire Fighting System to Extinguish Full Surface Fire of Large Scale Floating Roof Tanks

The basic characteristics of full surface fires of large scale floating roof tanks are briefed. It is pointed out that the present fire fighting systems of large scale crude oil storage depots cannot meet the need to extinguish full surface fires of large scale floating roof tanks. Adequate data of successful extinguishment of large scale tanks full surface fires and full scale tank fire experiments in the world are badly needed to design fire fighting system to extinguish full surface fires of large scale tanks in large scale crude oil storage depots. According to “Code of design for low expansion foam extinguishing system” and relative study results abroad, the fire fighting systems are calculated and designed to deal with full surface fires of large scale floating roof tanks. It is shown that designing parameters provided by API are more credible and large foam monitors act as the main fire extinguish facilities. The fire water supplying system is designed according to “Fire prevention code of petrochemical enterprise design”. The results show that the capability of the present fire fighting system should be raised up to at least 6-10 times to meet the need to extinguish full surface fires of large scale floating roof tanks. The reconstructing programs of fire fighting system are provided to deal with full surface fires of large scale floating roof tanks in the end.

Effect of Weld on Axial Buckling of Cylindrical Shells

Large oil storage tank (oil tank for short) shells are vulnerable to buckling damage when suffering the seismic loads. Numerical simulation analysis was taken to estimate the effects of the weld form, number and their location to axial buckling stress of cylindrical shells, considering not only the characteristic of welding processes, but also the effects probably caused by magnitude of residual stress and deformation on elephant foot buckling to oil tanks. It is revealed that the existence of circumferential welds had obvious negative effect on axial buckling critical stress compared with the structure without welds, while the effects of weld number and location were not as much; longitudinal welds had no visible effect on axial buckling critical stress; controlling the residual stress and deformation range caused by circumferential welds should be the key point during the tanks welding process.

大形石油タンクの底隅角部溶接継手の曲げ変形能を表わすパラメータについて (第3報) パラメータの誘導

大形石油タンクの底隅角部溶接継手の曲げ変形能を表わすパラメータについて (第3報) パラメータの誘導

Broadband Ground Motion Reconstruction for the Kanto Basin during the 1923 Kanto Earthquake

Ground motions of the 1923 Kanto Earthquake inside the Kanto Basin are numerically simulated in a wide frequency range (0–10 Hz) based on new knowledge of the earthquake’s source processes, the sedimentary structure of the basin, and techniques for generating broadband source models of great earthquakes. The Kanto Earthquake remains one of the most important exemplars for ground motion prediction in Japan due to its size, faulting geometry, and location beneath the densely populated Kanto sedimentary basin. We reconstruct a broadband source model of the 1923 Kanto Earthquake from inversion results by introducing small-scale heterogeneities. The corresponding ground motions are simulated using a hybrid technique comprising the following four calculations: (1) low-frequency ground motion of the engineering basement, modeled using a finite difference method; (2) high-frequency ground motion of the engineering basement, modeled using a stochastic Green’s function method; (3) total ground motion of the engineering basement (i.e. 1 + 2); and (4) ground motion at the surface in response to the total basement ground motion. We employ a recently developed three-dimensional (3D) velocity structure model of the Kanto Basin that incorporates prospecting data, microtremor observations and measurements derived from strong ground motion records. Our calculations reveal peak ground velocities (PGV) exceeding 50 cm/s in the area above the fault plane: to the south, where the fault plane is shallowest, PGV reaches 150–200 cm/s at the engineering basement and 200–250 cm/s at the surface. Intensity 7, the maximum value in the Japan Meteorological Agency’s intensity scale, is calculated to have occurred widely in Sagami Bay, which corresponds well with observed house-collapse rates due to the 1923 event. The modeling reveals a pronounced forward directivity effect for the area lying above the southern, shallow part of the fault plane. The high PGV and intensity seen above the southeastern corner of the fault plane and further east are largely due to this effect. Waveforms above the fault plane contain both short- and long-period components, but the short-period components are not observed further afield. Away from the fault, long-period waves (>2 s) dominate the ground motion, and in areas where the base of the third layer is relatively deep, the predominant period is >5 s. Levels of long-period ground motion in the southern part of the study area, around Sagami Bay and the southern parts of Boso Peninsula and Tokyo Bay, exceed that recorded at Tomakomai during the 2003 Tokachi-oki earthquake, when large oil storage tanks collapsed in response to sloshing generated by strong long-period motions.

Axisymmetric Finite Element Analysis for Sloshing Response of Floating Roofs in Cylindrical Storage Tanks

Floating roofs are widely used to prevent evaporation of the contents of large oil storage tanks. The 2003 Tokachi-Oki earthquake caused severe damage to floating roofs due to liquid sloshing. Establishing the structural integrity of floating roofs subjected to sloshing is an urgent issue for the petrochemical and oil refining industries. The present paper proposes an axisymmetric finite element analysis for the sloshing response of floating roofs in cylindrical storage tanks. The hydrodynamic coupling of the fluid and the floating roof under seismic excitation is taken into consideration in the analysis. The fluid is assumed to be incompressible and inviscid, and the roof is assumed to be linear elastic. In addition, the sidewall and the bottom are assumed to be rigid. The theory for the finite element analysis, in which the behavior of the fluid is formulated in terms of dynamic pressure using the Eulerian approach, is proposed. The basic vibration characteristics of the floating roof, such as the natural frequencies and vibration modes, can be obtained from this analysis. These characteristics provide engineers with important information on the floating roof design.

Influence of Direct Quenching on Microstructure and Mechanical Properties of Steel Plate for Large Oil Storage Tanks

The influence of direct quenching on microstructure and mechanical properties of high performance steel plates for large oil storage tanks was studied. The direct quenched and tempered (DQ&T) steel plates were rolled at different finish rolling temperatures (1113 and 1173 K), and their microstructures and mechanical properties were compared with those of reheat quenched and tempered (RQ&T) steel plate. The optical microscopy of the DQ steel shows deformed grains elongated along the rolling direction, while complete equiaxed grains are visible in RQ steel. Transmission electron microscopy (TEM) of the DQ steel shows refined lath martensite with high density of dislocations, which acts as preferred precipitation sites for NbC or Nb(C,N) particles during tempering. In all the plates, strength decreases with increasing tempering temperature. The strength of RQ steel increased significantly compared with that of DQ steel at the higher tempering temperature, which leads to better tempering resistance in DQ steels. The optimum combination of strength and toughness (yield strength (YS) reaches 585 MPa, tensile strength (TS) 667 MPa, and Charpy impact energy at 253 K of 291 J) in the DQ steels is achieved by quenching at 1113 K and tempering at 923 K.

263 センターポンツーン付きシングルデッキ形浮屋根式タンクのスロッシング

The floating roofs are widely used to prevent evaporation of content in large oil storage tanks. The 2003 Tokachi-Oki earthquake caused severe damage to the floating roofs due to liquid sloshing. Several damaged floating roofs in large diameter tanks were the single deck type with center pontoon. This paper presents the sloshing characteristics of a single deck floating roof with center pontoon in cylindrical storage tank. The hydrodynamic coupling of fluid and floating roof is taken into consideration in the axisymmetric finite element analysis. It is assumed that the fluid is incompressible and inviscid, and the floating roof is linear elastic while the sidewall and the bottom are rigid. The basic vibration characteristics, natural periods and vibration modes and so on, of the floating roof due to the sloshing are investigated. These will give engineers important information on the design.

Axisymmetric Finite Element Analysis for Sloshing Response of Floating Roofs in Cylindrical Storage Tanks

The floating roofs are widely used to prevent evaporation of content in the large oil storage tanks. The 2003 Tokachi-Oki earthquake caused severe damage to the floating roofs due to liquid sloshing. The structural integrity of the floating roofs for the sloshing is urgent issue to establish for the petrochemical and oil refining industries. This paper presents the axisymmetric finite element analysis for the sloshing response of floating roofs in cylindrical storage tanks. The hydrodynamic coupling of fluid and floating roof under seismic excitation is taken into consideration in the analysis. It is assumed that the fluid is incompressible and inviscid, and the roof is linear elastic while the sidewall and the bottom are rigid. The theory for the finite element analysis in which the behavior of the fluid is formulated in terms of dynamic pressure as the Eulerian approach is developed. The basic vibration characteristics of the floating roof, such as natural frequencies and vibration modes, can be obtained from the analysis. These give engineers important information on the floating roof design.

Sloshing Characteristics of Single Deck Floating Roofts in Cylindrical Storage Tanks (Natural Periods and Natural Vibration Modes)

The floating roofs are widely used to prevent evaporation of content in the large oil storage tanks. The 2003 Tokachi-Oki earthquake caused severe damage to the floating roofs due to liquid sloshing. The structural integrity of the floating roofs for the sloshing is urgent issue to establish in the petrochemical and oil refining industries. This paper presents the sloshing characteristics of single deck floating roofs in cylindrical storage tanks. The hydrodynamic coupling of fluid and floating roof is taken into consideration in the axisymmetric finite element analysis. It is assumed that the fluid is incompressible and inviscid, and the roof is linear elastic while the sidewall and the bottom are rigid. The basic vibration characteristics, natural periods and vibration modes, of the floating roof due to the sloshing are investigated. These will give engineers important information on the floating roof design.