Tank Dome Research Articles

A novel stability analysis method of single-layer ribbed reticulated shells with roof plates

The steel dome of liquefied natural gas (LNG) storage tanks comprises a curved roof plate welded onto a single-layer ribbed reticulated shell (SLRR shell). However, the roof plate may cause diaphragm effects, which may resulting in instability of the steel dome at a relatively low load level. In this paper, an innovative equivalent single-layer ribbed reticulated shell (ESLRR shell) was proposed to investigate the impact of the diaphragm effect. Specifically, the roof plate and H-shaped radial beam were equated as radial irregular beams based on the principle of plate-shell composite action. Next, we performed a systematic analysis of the instability mechanisms in the ESLRR shell, revealing the interaction between the beam buckling and the overall structural instability. Finally, through parametric study, we explored the effects of roof plate thickness and rise-to-span ratio on the ESLRR shell, and obtained the optimal structural parameters. The results show that the proposed method effectively solves the challenges associated with the presence of roof plates in LNG storage tanks steel dome stability analysis; Under the combination of weak boundary stiffness and high bending moment, radial irregular beams are more prone to buckling; Increasing roof plate thickness or rise-to-span ratio can reinforce the stability of the ESLRR shell. Overall, this research work provides theoretical guidance for the future design and optimization of LNG storage tank domes.

A Two-Step Marginal-Restraint Mandrel-Free Spinning Method for Accuracy in Forming Large, Special-Shaped Aluminum Alloy Tank Domes

The special-shaped tank dome of a launch vehicle is a large, thin-walled, curved structure that is difficult to form using the conventional center-restraint spinning method. This study proposes a two-step marginal-restraint mandrel-free spinning method for forming large domes. The finite element analysis results indicate that a larger roller fillet radius and larger feed ratios lead to a larger upper convex angle and the minimum thickness value for the bottom contour. This study explored the impact of shape parameter variations on the upper convexity and transition rounding angle on forming accuracy. The results show that the convexity of the bottom of the special-shaped domes increases with a larger roller fillet radius and larger feed ratios while the overall height decreases. The forming accuracy is adversely affected by larger transition rounding angles and smaller upper convexities. For the accurate forming of domes, the mutual coupling influence during two-step forming should be considered, and a suitable process and suitable trajectory compensation parameters must be carefully selected. Finally, the study verified that a two-step marginal-restraint mandrel-free spinning method with a 10 mm roller fillet radius, a 2 mm/r feed ratio, and the corresponding trajectory compensation can achieve the precise forming of 2250 mm thin-walled special-shaped domes.

Vapor cooling of a structural skirt for a large-scale hydrogen tank

The demonstration of vapor cooling on a structural skirt was one of the main objectives of the Structural Heat Intercept, Insulation, and Vibration Evaluation Rig (SHIIVER) testing. SHIIVER consisted of a 4-meter diameter stainless steel tank with an aluminum forward skirt. The forward skirt was cooled by directing effluent vapor from the tank through two flow channels that each went 360 degrees around the interior of the skirt in a helical pattern. Flow rates, temperatures, and pressures in the system were measured allowing for the calculation of heat load removed via cooling stream and heat load reduction into the tank. Testing occurred at fill levels between 25% and 90% full using both liquid hydrogen and liquid nitrogen. Boil-off rate was varied independent of the skirt performance by adding multilayer insulation over the spray-on-foam insulation on the tank domes, while leaving the barrel insulated only with spray-on-foam. The results from the testing, which demonstrate vapor cooling removed heat flow from the tank flange and reduces total propellant heat load by as much as 19%, are analyzed and discussed.

Вибір оптимальної конструкції забірного пристрою у баку пального першого ступеню ракети-носія «Циклон-4»

The residues of rocket propellant in tanks after the launch vehicle stage burnout have a substantial influence on the launch vehicle power budget. In modern launch vehicle tanks, the intakes maintain the continuous supply of propellants from a tank to the propulsion system, keeping the continuity of flow and minimizing the number of residual propellants. Tunnel pipelines in the launch vehicle propellant tanks make it complicated, or impossible in certain cases, to take in propellants from a tank pole. A lateral intake can be a solution to the issue of propellant intake in this situation. However, the displacement of such devices by a certain angle relative to the tank dome can cause blow-by fluctuations at the feed line inlet and, consequently, a much larger number of residual propellants. The analysis of an optimum lateral intake design was carried out and the authors explain the grounds for the design of a lateral intake shaped as a profiled plate, using as an example the third stage of the Cyclone-4 launch vehicle where a device of such a type is used. The siphon and annular designs of an intake are considered, the calculations of their key parameters were made, and a comparative analysis was done for the power budgets of launch vehicles with the considered intake designs. The effectiveness of the considered intake designs was determined by the value of the level drop depth (Hcr) under static conditions that directly define the mass of non-burnt propellant residues. The results of the conducted analysis and computations demonstrated the siphon intake to be the optimum design option by many parameters. The use of an upgraded lateral siphon intake in the Cyclone-4 propellant tanks will allow the payload to orbit to be 4.4 kg heavier, thereby resulting in a better power budget for the launch vehicle.

An analytical method for the thermo-mechanics coupling study of thin-walled spherical shell structure

For large LNG storage tanks, the thermal load has a very important influence on the failure mode of the thin-walled spherical dome. However, the traditional calculation of thermal stress is very complicated for the spherical shell. To obtain an analytic solution with a simple expression, an approximate method was proposed in this paper. The mechanical behaviour caused by the temperature difference is divided into two parts, i.e. the thermal strain directly acting on the shell and the binding force exerted by the boundary. The thickness is ignored in the calculation of deflection caused by boundary constraints. Then, its accuracy was verified by a linear elastic numerical model. Furthermore, the crack pattern in a nonlinear plastic simulation was also well captured. The case study shows that the thermal-induced meridional cracks distribute uniformly along the circumferential direction; these cracks first appeared on the inner surface at the edge of the tank dome, and then rapidly expand to the centre and outer surface; increasing the amount of reinforcement cannot effectively limit the development of such cracks.

LNG Tank in Świnoujście: Nonlinear Analysis of the Tank Dome Elements Behaviour

Abstract In this paper, the dome of a tank in the Świnoujście LNG terminal is analysed. Some of the rafter ribs at the connection with hangers were not mounted during construction of the tank dome. Therefore, it has become necessary to estimate its response, which has been done with the aid of some computational models of the dome, that have been created in the finite element method environment. Different local models are studied, aiming to recreate possible outermost conditions of the tank dome response, i.e. with or without composite action between steel and concrete parts of the tank dome. Static calculations with material and geometric nonlinearities are carried out on the computational models, enabling the creation of a load capacity envelope of the rafter with or without ribs. The obtained results are then used to decide if repair works need to be done and whether the missing ribs should be welded.

浅议国际EPC项目管理中储罐铝制拱顶漏水的预防对策及措施

浅议国际EPC项目管理中储罐铝制拱顶漏水的预防对策及措施

Collapse of reticulated domes, a case study of Talakan oil tank

In this paper, instability of single layer reticulated domes is discussed. This purpose is elaborated by a case study on Talakan oil tank dome which is analyzed in this work with research package. This paper provides technical information related to the design, fabrication and collapse of Talakan dome. The secondary paths, especially in unstable buckling, can play an important role in the loss of stability and led to failure of the structure. The authors show that the stiffness of the dome is not adequate to prevent buckling under the prescribed snow loads. It is also shown that the capacity of the dome to resist eccentric snow load is about half of its capacity to resist symmetric snow loads. Although six combinations of load and support fixity are included in design assumptions, considerable attention has been focused on the bifurcation behavior in Talakan dome. The stiffness of the aluminum sheets of the roof cover have not been taken into account in the stability analysis.

A Study on Post Weld Heat Treatment of Friction Stir Welded Al2195 Blank for Spin Forming

It is well known that the significant weight reduction and increased strength have placed advanced aluminum-lithium alloys at the forefront of aerospace materials research. For example the use of aluminum-lithium based alloys for rocket fuel tank domes can reduce weight because aluminum-lithium alloys have lower density and higher strength than Al-Cu alloy 2219. However, Al-Li alloys have been shown the inherent low formability characteristic that make them susceptible to cracking during the spinning operations. In this study a novel heat treatment process on the formability of friction stir welded Al-Li alloy blanks are presented. It is shown that the successful heat treatment process has been developed with superior mechanical properties and currently the patent is applied.

Structure Design and Stability Calculation of Large Storage Tanks with a Reticulated Shell Dome

With the large-scale development of refined oil storage tanks, adopting spatial reticulated hell structures as the tank dome is becoming an inevitable trend. Although reticulated shell structures have mature theory and design experience in the field of architecture, there are still many technical problems about its application in large storage tanks. The advantages and disadvantages of existing large reticulated shell structures are analyzed and compared and the selection opinions of grid type, bar section and node form are given against the structural features of large storage tanks with a reticulated shell. In order to improve the connection security of the reticulated shell and lower tank body, a new bearing structure is proposed which is applicable for large storage tanks with a reticulated shell. The calculation method for overall stability of reticulated shell dome is discussed, the critical buckling load will be calculated by the method of whole process analysis of load-displacement considering geometric nonlinearity, and the influence of lower tank body, different constraint conditions and installation deviations on the stability capacity of a reticulated shell dome. Moreover, a 50 000 m3 large storage tank with a reticulated shell is used as an example to conduct case analysis according to related standards, such as JGJ7-2010 Technical specification for space frame structures, which verities that relevant specifications are also applicable for tank reticulated shells.

LNG Tank Dome Air Raising Technology Research Based on Closed-Loop Tension Control

LNG gains popularity as a kind of clean and efficient energy, LNG tank dome air raising installation technology is a key problem for tank construction, chain preloaded is adopted in traditional balance guidance device, the wire rope tension cant maintain a constant in air raising, which brings great safety hidden trouble. In this paper, the tension control technology based on closed-loop was put forward, the tension control device was designed and the hydraulic system principle was designed. Tensioning force can be adjusted automatically in the air raising process by researching on LNG dome air raising technology based on closed-loop tension control. It is of great significance for improving the efficiency and safety in the process of air raising .

Seal Optimization Technology Research of Large LNG Storage Tank Dome Gas Lift

Dome gas lift is the technical difficulties of a large LNG (liquefied natural gas) tanks in the process of construction. The sealing structure is one of the core link in the process of the gas lift. In this paper, the seal structure of large LNG storage tank dome gas lift is studied. A new kind of sealing structure is designed by using gap seal. This paper has carried on the simulation analysis with ANSYS software to verify the feasibility of new type sealing structure. This kind of sealing structure can reduce the friction in the process of gas lift. It also can use the smaller contact area to achieve good sealing effect. The method has important practical value in enhancing the security of gas lift of LNG storage tank dome.

The Design of Pressure Regulating System for Large LNG Storage Tank Dome Gas Lift

Dome gas lift is one of the core link in the process of the construction of a large LNG (liquefied natural gas) storage tank. The process of traditional gas lift is relying on the working experience to control the gas pressure inside the storage tank, which has low control precision and poor operability. In this paper, a kind of PID control method was designed through the analysis of the gas lift process and the data was extracted as the feedback parameters by multi-point gas pressure sensors. Simulation was proceeded by the MATLAB software. The results show that, this PID control method can automatically adjust the pressure of the process of gas lift. And it also has fast, stable and reliable control performance. This method has important practical value in improving the control precision of the large LNG storage tank gas lift.

High strain rate deformation and cracking of AA 2219 aluminium alloy welded propellant tank

Aluminium alloy AA 2219 (Al–6.6Cu–1Mn) is the candidate material for the fabrication of propellant storage tank of launch vehicle. Cold rolled sheets of 6.5 mm thickness are used to make the cylindrical shell, while sheets of 4.5 mm thickness are used for the construction of dome through petal forming technique. Petals, formed through cone rolling, treated to T87 temper condition are welded together by TIG welding to configure the dome. Such domes are joined to the cylindrical shell through a ring by TIG welding. The upper stage consists of two tanks, one oxidizer tank (liq. O 2) and other fuel tank (liq. H 2). After completing various developmental qualification tests, propellant flow rate test of one of the system was carried out. Almost all the liquid oxygen of the tank was removed and only a little quantity remained at the bottom. During one of the subsequent tests; when dry nitrogen gas was purged to evaporate the remaining liquid oxygen, the oxidizer tank dome catastrophically fractured with an audible sound. Fracture of oxidizer tank dome, placed at lower part of the system caused excessive deformation and subsequently it also caused fracture of fuel tank dome placed just over it. Detailed metallurgical investigations were carried out on the failed components and it was found that the tank failed under very high strain rate deformation. This paper brings out the details of the investigation carried out.

Impact Assessment of Existing Vadose Zone Contamination at the Hanford Site SX Tank Farm

The USDOE has initiated an impact assessment of existing vadose zone contamination at the Hanford Site SX tank farm in southeastern Washington State. The assessment followed the Resource Conservation and Recovery Act (RCRA) Corrective Action process to address the impacts of past tank waste releases to the vadose zone at the single‐shell tank farm. Numerical models were developed that consider the extent of contamination presently within the vadose zone and predict contaminant movement through the vadose zone to groundwater. The transport of representative mobile (technetium‐99) and immobile (cesium‐137) constituents was evaluated in modeling. The model considered the accelerated movement of moisture around and beneath single‐shell tanks that is attributed to bare, gravel surfaces resulting from the construction of the underground storage tanks. Infiltration, possibly nearing 100 mm yr−1, is further amplified in the tank farm because of the umbrella effect created by percolating moisture being diverted by the impermeable, sloping surface of the large, 24‐m‐diameter, buried tank domes. For both the base case (no‐action alternative) simulation and a simulation that considered placement of an interim surface barrier to minimize infiltration, predicted groundwater concentrations for technetium‐99 at the SX tank farm boundary were exceedingly high, on the order of 106 pCi L−1 The predicted concentrations are, however, somewhat conservative because of our use of two‐dimensional modeling for a three‐dimensional problem. A series of simulations were performed, using recharge rates of 50, 30, and 10 mm yr−1, and compared to the base case (100 mm yr−1) results. As expected, lowering meteoric recharge delayed peak arrival times and reduced peak concentrations at the tank farm boundary.

Model of the filling of an automotive fuel tank

One of the problems associated with automotive fuel tanks is premature shut-off during the filling process. This occurs when the fuel dispensing nozzle shuts off before the fuel tank is completely filled. A comprehensive but simplified lumped parameter model has been developed to determine the pressure and flow rate associated with the automotive fuel tank for the purpose of predicting premature shut-off. Unlike previous work, this model includes the entire fuel system, including a closed rectangular tank with a filler tube, rollover valve, and vent tube that connects the filler tube to the tank. The system was divided into several control volumes and connecting valves. Continuity equations were written for each of the control volumes and energy equations were written for each of the connecting valves. The model includes the effects of the fuel tank system geometry, fuel nozzle dispensing rate, fuel volatility, multiphase, multicomponent flow through the filler tube, air/fuel vapour in the tank dome, vapour generation and choking in the vent tube, and the rollover valve due to the low speed of sound of the vapour droplet flow. This mathematical model consists of five nonlinear, integral equations and a number of algebraic equations. A commercial numerical solver (Simulink) was used to solve these equations subject to appropriate boundary conditions. The simplified model was used to generate results to compare with existing experimental results. In spite of its simplicity, it was capable of predicting the nature of the shut-off for all of the corresponding sets of experimental data. Prediction of the magnitudes of the tank dome pressure and the filler tube pressure were, however, only in fair agreement with the experimental values. The model was also used to perform a sensitivity analysis of model parameters. The results were found to be most sensitive to vent area around the filler nozzle, liquid dispensing flowrate, and fuel volatility.

Dynamics of contained liquids: A personal odyssey

Dynamics of contained liquids: A personal odyssey

Thermal degradation of the concrete roof of high-level waste storage tank

The DOE's high-level waste storage tank (HLWST) sites consist of single- and double-shell concrete tanks covered with soil overburden. Due to the high temperature (212 °F and above) of the liquid-filled waste, the concrete walls and domed roofs are expected to endure thermal degradation which, in turn, may lead to cracking of the concrete. A remote video camera inspection of one such HLWST indicated some ‘irregularities’ on the inner surface of the tank dome. A finite element model using ADINA was developed to simulate the field conditions including concrete strength deterioration. The model was first validated against the results obtained from tests conducted on a 1 10 th-scale model. The analysis was then extended to study the actual field behavior. The results confirmed the overall structural integrity of the tank by considering the global response of the tank and a detailed analysis of likely crack patterns in the dome area. The paper describes the complexities in validating the scale model as well as prototype response.

ON THE FATE OF SINUSOIDAL RADIATION TO A VOLATILE OPAQUE LIQUID

A method was developed that predicts the energy distribution of sinusoidal radiation incident on a volatile opaque liquid surface. The energy is absorbed by the liquid phase, absorbed by the gas phase and used to furnish the heat of vaporization of the volatile liquid. In an example of heptane and air, 94.8% of the energy conducted into the liquid phase 1.0% was conducted into the gas phase and 4.2% was required for the heal of vaporization The method could be used to determine the emissivity of a material radiating to a volatile opaque liquid. Results may also find application in reducing hydrocarbon emissions from fixed-roof tanks by as much as 30% if aluminum instead of steel tank domes were used

Full Scale Measurements on LPG Carrier of Semi-Membrane Tank Type under Servise Condition

In this paper a summary of results is presented of full scale measurements on a LPG carrier of semi-membrane tank type which have been carried out for about two years during her voyage between Japan and the Persian Gulf.The unmanned measurements have been made on dynamic loads caused by liquid sloshing in a LPG tank of a restricted cargo filling ratio of either over 90% or below 30%. The test includes also measurements of reaction forces acting on a tank dome supporting the tank at upper deck structure. Long term measurements of ship notion as well as stresses due to longitudinal bending of hull girder have also been carried out. A statistical study has been made on a relationship between the ship motion and the frequency of occurrence of the liquid sloshing in LPG tank.The results of the measurements have been compared with results of bench test on liquid sloshing in model tank in order to investigate into the effect of tank size on the magnitude of impact load due to sloshing.