Ground Storage Tanks Research Articles

Probabilistic assessment of material failure in anchored above ground storage tanks during flood events

This study investigated material failures – yielding and rupture – in shell and bottom plates in anchored above ground storage tanks’ (ASTs) during flood events. Existing studies have assessed shell buckling in anchored ASTs during hurricanes and floods, however, material failure in ASTs – i.e., in tank shell and bottom plate - due to flood load has received limited attention. To this end, a finite element simulation-based approach was used wherein, first, design parameters such as tank diameter, relative density and height of stored contents, yield stress, inundation depth and bottom plate thickness were sampled using Latin Hypercube Sampling (LHS). For each design parameter combination, an AST was designed and maximum von Mises streses in bottom plate and tank shell were determined from finite element analysis for various flood depths and were compared against two different failure thresholds corresponding to material yielding and rupture. The results from finite element simulations revealed that even after considering buckling of the tank shell, bottom plate is more vulnerable to material yielding and rupture and would fail first before tank shell during flood events. These results were used in step wise logistic regression to develop parameterized fragility models. These models were applied to four case study tanks to estimate probability of failure, spill volumes, and required fill level to prevent failure. Bottom plate failure was found to initiate at low inundation depth for larger diameter tanks. Probability of failure of anchored bottom plate was found to be higher when compared with tank shell buckling. It was also found that anchoring the tanks, especially larger diameter tanks, was not effective in preventing spills during flood events due to bottom plate failure. Comparison of minimum fill levels to prevent flotation of unanchored tanks and bottom plate failure in anchored tanks against common rules of thumb showed that higher liquid levels might be needed to prevent bottom plate failure in case of larger diameter tanks. Results from this study suggested that tanks should be allowed to float in a controlled manner, and thus bottom plate failure and uncontrolled flotation induced spills could be prevented.

A one-dimensional transient temperature prediction model for Chinese assembled solar greenhouses

The prediction of the thermal environment of greenhouses has always been an essential component of greenhouse development. In this paper, a one-dimensional transient temperature prediction model is constructed based on the principle of energy balance for Chinese assembled solar greenhouses (CASG). The daily temperature trends for each surface in the greenhouse were obtained by solving the model using MATLAB. The performance of the model was assessed by comparing the measured and predicted values. The mean absolute errors for the temperature of air, back roof, front roof, heat collector plate, north wall, ground and water storage tank were computed to be 1.4 °C, 1.89 °C, 1.98 °C, 2.07 °C, 2.26 °C, 1.44 °C and 0.68 °C, respectively. The results demonstrate a high level of concurrence between the simulated and measured values, indicating that the model is proficient in predicting the thermal environment of CASG. Based on this, predictions were made regarding the internal environment of CASG on both sunny and cloudy days, which contributes to a comprehensive understanding of the thermal environment. The research provides theoretical support for regulating environmental conditions of CASG.

A comparative numerical evaluation of linear anode arrangements for enhancing above ground storage tank cathodic protection via mesh grid and concentric ring designs

Cathodic protection as a complementary method is one of the most effective ways to prevent corrosion, along with coating and choosing the suitable material. There are different ways to protect the storage tank bottom. Due to the presence of the geo membrane layer and its effective and pivotal role, the use of mixed metal oxide (MMO) anodes is highly recommended. In the current study, the protection process of the above-ground storage tank bottom is simulated using MMO backfilled wire (concentric rings) and ribbon anodes (mesh grid system). In this regard, several parameters must be considered in reaching the protection criteria. The simulation results show that the effect of the limiting oxygen current density, soil resistivity and the anodic current have the greatest role. Anode depth and the spacing between the anodes are also critical factors if they have large values. Due to the importance of the number of conductor bars and feeding cables, two configurations have been presented for ribbon anodes. These configurations have a direct impact on grid resistance, rectifier size, and related costs. Finally, an economic comparison has been made regarding the use of sacrificial and MMO anodes in the form of ribbon next to wire anodes. The results show that, in the use of ribbon anodes, MMO anodes have better performance than magnesium and zinc sacrificial anodes, and the cost required for MMO linear anodes is far lower than the method of sacrificial ribbon anodes. In the present study, the cost of the MMO linear anode system is approximately 20% of zinc and magnesium sacrificial ribbon anode system cost.

Analyzing and design of mesh ribbon cathodic protection for aboveground storage tanks

Aboveground storage tanks are widely used for storage of liquids. The bottom of these tanks rest on the soil and is prone to the corrosion. Due to the use of geo-membrane liner in some cases, the bottoms of these tanks can only be protected from corrosion by using distributed mesh ribbon anodes. Up to now, there is no an accurate and comprehensive calculation for current distribution in such configurations. For this reason, the spans of the ribbon anodes and conductor bars are mostly chose based on simple and handy formulas, which may not be correct and optimum enough. Therefore, in this paper, the current distribution is calculated based on a 2D model and considering coating and polarization effect and then applied for determining the anodes span. Furthermore, the current attenuation in the ribbons and conductor bars are calculated for determining the spans between the conductor bars. Finally, based on the achieved formulas, two designs are presented and compared and the results of them are validated by Finite element method simulations. The results of this paper could be used for optimum design of cathodic protection systems for bottom of the above ground storage tanks.

Fragility assessment of bottom plates in above ground storage tanks during flood events

This study aims to improve the fundamental understanding on the performance of bottom plates in above ground storage tanks (ASTs) during flood events. To this end, fragility models that estimate the probability of material yielding and rupture in the bottom plates were derived. A significant number of ASTs are located in coastal areas and are susceptible to hurricane hazards. Consequently, ASTs have suffered severe damage during past hurricanes resulting in spills with catastrophic environmental and social impacts. Therefore, several failure modes such as flotation, buckling, and sliding have been studied in past research. However, the literature lacks studies that consider the failure of bottom plate due to uplift pressure generated during floods and there are no design guidelines to address this issue. To address this gap, fragility functions that provide the probability of failure as a function of tank geometry, material properties, design parameters, and hazard conditions were developed herein. For this purpose, Latin Hypercube Sampling was performed to span the space of these parameters uniformly. For each parameter combination, maximum stresses in bottom plates were determined using analytical formulations for simply supported and clamped boundary conditions and were compared against two different failure thresholds. The results were used to develop a closed form fragility model using step wise logistic regression. Fragility functions were applied to four case study tanks. Sensitivity analysis were performed to understand the impacts of different probability density functions for various variables on the bottom plates’ fragility. The results provided several insights such as ASTs with larger diameter were vulnerable to bottom plate failure. Comparison with other failure modes revealed that the probability of bottom plate failure was higher than flotation failure for anchored ASTs with clamped boundary condition.

Drone Based Inspection of Above Ground Storage Tanks. A Multi Criteria Evaluation Approach

Unmanned Aerial Vehicles (UAVs) is an emergent technology with the potential to drastically change the landscape of many civil and industrial activities in the near future. A promising field of application is the inspection and monitoring of industrial plants, where UAVs can be a valid alternative to traditional approaches with a better cost-effectiveness and a higher safety level. Although the disruptive innovative potential of this technology is generally recognized, a consistent methodological approach towards the evaluation of the drawbacks and benefits of employing UAVs in critical industrial operations can hardly be found in the current scientific literature. In such context, this paper proposes a framework for assessing the effectiveness of UAV technology in industrial monitoring applications within a structured multi-objective framework. In particular, the paper compares the traditional ground-based inspection services of Above Ground Storage Tank (AST) with UAV based inspection, by means of the well-known Analytic Hierarchy Process (AHP) method considering time, cost and safety criteria. A case study is also proposed to demonstrate the effectiveness of the approach proposed.

Thermal performance of greenhouse heating with loop heat pipe solar collector and ground source heat pump

The hybrid heating system consisting of loop heat pipe solar collector (LHPSC) and ground source heat pump (GSHP) is proposed to control greenhouse temperature in Harbin (the coldest provincial capital of China) in this paper. The combined thermal resistance network and energy balance model is developed to predict transient greenhouse temperature corresponding to the energy supplied by GSHP. The influence of ambient temperature on the thermal performance of greenhouse heating system is analyzed. The results show that the greenhouse temperature fluctuates in the range of 17–24 °C corresponding to the energy of 200 kW intermittently supplied by GSHP, which is reasonable for predicting greenhouse temperature in severely cold regions. As ambient temperature varies from −24 °C to −13 °C, heat loss of maintenance structure, ground, ventilation and water storage tank change in the range of 51.9–73.2 kW, 2.45–3.45 kW, 11.1–15.5 kW and 5.87–6.91 kW, respectively. The maximum thermal efficiency of loop heat pipe solar collector is higher (76.38%) than that of evacuated tube solar collectors (45%–50%), which will be promising for greenhouse heating due to higher thermal efficiency and better environmental adaptability. The results presented in this study will provide further valuable guidelines for designing greenhouse heating system.

Numerical Analysis of Fire Water Storage Tank under Seismic Loading

Maintenance and continuously monitoring the condition of above ground storage tanks are significant when the tanks are placed in service. The American Petroleum Institution (API) 653 and other international codes provides the minimum requirements for inspection & maintaining the integrity of tanks during its service. The tank settlement is one of the major threats for tank’s integrity. In this paper, a storage tank is assessed for uniform settlement under various loading condition such as seismic, dead load, static load, corrosion loss of shell plate etc. In the present study, a finite element model is designed with uniform settlement condition and study of its governing hoop stress at shell plate has been carried out under different loading conditions. A fire water storage tank (constructed with IS 2060 GR. B material) and different seismic zones in India are taken for this study. The finite element analysis simulation shows that increase of hoop stress in the bottom shell course due to uniform settlement, the decrease in plate thickness and with different seismic active regions. Moreover, the maximum stresses have been observed at shell bottom course (close to bottom plate).

NSF Response Case Study: Hazardous Materials Release at Intercontinental Terminal Company, Deer Park, Texas

ABSTRACT On March 17th, 2019 the Intercontinental Terminal Company (ITC) Deer Park, Texas river terminal and storage facility, comprised of 242 above ground storage tanks with a site capacity of 13.1 million barrels of hazardous products, experienced a tank fire. This incident would also become known as the “2nd 80s Fire” based on the identification of tanks impacted. The fire was contained to a single grouping of 15 tanks, with stored products including Naphtha, Toluene, Xylene, Benzene, Pyrolysis Gasoline, and Gasoline Blend stocks. Extended firefighting efforts resulted in volumes of water and firefighting foam that exceeded the capacity of the containment systems, resulting in the subsequent containment failure on March 22nd, which enabled the hazardous chemicals and mixture of various products to eventually reach the Houston Ship Channel. The surrounding industrial and residential communities experienced shelter-in-place orders due to the air quality concerns, and the vital waterway was shut down to commercial traffic. On-water benzene levels exceeded 20 parts per million (ppm) during the initial phases of the response near the facility while many areas within five miles exceeded the Occupational Safety Health Agency (OSHA) Permissible Exposure Limit (PEL) for benzene exposures. Benzene remained the primary chemical hazard to response crews seeking to contain, remove, and reopen the waterways for more than two weeks past the initial chemical release events. An interagency agreement was developed between the Environmental Protection Agency (EPA) and the U.S. Coast Guard (USCG) to assist in response activities, which included containing, collecting, recovering and disposing of the released materials from the shoreline and the surface water. The National Strike Force (NSF) deployed 52 personnel from each of the three Strike Teams, Public Information Assist Team (PIAT) and CG-Incident Management and Assistance Team (CG-IMAT). Due to the elevated presence of benzene, the NSF was the only USCG trained, experienced and qualified organic response resource prepared to respond to environmental threats with elevated concentrations of products that represented an inhalation hazard requiring respiratory protection devices. This paper demonstrates the significance of NSF's respiratory protection program, and how their capabilities can be used for both technical operations support, and also for site safety management, especially during complex spills or releases.

Design of an Ionic Conductor as Permanent Electrode for Monitoring Cathodic Protection System performance.

The most dominant used method for protecting the bottom of a tank is impressing a current cathodic protection (ICCP). Monitoring the CP system is critical to maintain and extend the service life of the exterior bottom of the storage tank. The bottom of the tank usually located on or near the surface of the ground and in contact with materials used to support the tank and so presents a corrosion challenge. This work presents a successful design of an ionic conductor that can be used as a monitor procedure of ICCP system for ground storage tanks bottom. The new ionic conductor system offers an accurate and efficient performance compared with old copper/ copper sulphate electrode monitoring system. The risks failure of permanent electrodes including cables disconnection and electrode dryness are increasing. Ionic conductors were used to insure proper potential monitoring. The new ionic conductor system scheme has the features of lower cost and less installation time over conventional methods.

Structural health monitoring of liquid filled above ground storage tank floors: a time-reversed approach to acoustic emission source location

Acoustic Emission (AE) is a proven successful Non-Destructive Testing (NDT) method to assess the state of storage tank floors. Traditional AE source location in tanks floors is performed using only the wavefronts that have traveled directly from the source to the sensor (direct hit). The wavefronts captured after reflected from the tank walls are identified and discarded. This paper proposes a new AE source location algorithm in tanks that considers a combination of reflections and direct hits. The proposed algorithm is based on time-reversed acoustics and ray theory. The methodology uses the concept of time-reversed acoustics in which a wave detected at any location can be directed back to the source when re-created at the detection place. Therefore, the developed approach takes the time at which each wave arrives to the sensor and sends it back as if time had reversed. Ray theory is used in the methodology to account for the way in which the wavefront is reflected when encounters an obstacle such as the walls of the tank. Then, the point of intersection of all wavefronts is identified using an optimization algorithm. This point where all wavefronts intersect is considered the location of the source. The location algorithm considers the first path or direct hits from the source to the sensors combined with reflections obtained by wavefronts bouncing from the tank walls. The proposed location algorithm was validated using numerical data from 176ft diameter tank and experimentally using AE data from a tank 55ft diameter.

Two-phase convection heat transfer correlations for liquid hydrogen pipe chilldown

Recently, heat transfer correlations based on liquid nitrogen (LN2) and liquid hydrogen (LH2) pipe quenching data were developed to improve the predictive accuracy of lumped node codes like SINDA/FLUINT and the Generalized Fluid System Simulation Program (GFSSP). After implementing these correlations into both programs, updated model runs showed strong improvement in LN2 pipe chilldown modeling but only modest improvement in LH2 chilldown modeling. Due to large differences in thermal and fluid properties between the two fluids, results indicated a need to develop a separate set of LH2-only correlations to improve the accuracy of the simulations. This paper presents a new set of two-phase convection heat transfer correlations based on LH2 pipe quenching data. A correlation to predict the bulk vapor temperature was developed after analysis showed that large departures from thermal equilibrium between the liquid and vapor phases occurred during film boiling of LH2. Implemented in a numerical model, the new correlations achieve a mean absolute error of 19.5 K in the predicted wall temperature when compared to recent LH2 pipe chilldown data—an improvement of 40% over recent GFSSP predictions. This set of correlations can be implemented in simulations of the transient LH2 chilldown process. Such simulations are useful for predicting the chilldown time and boil-off mass of LH2 for applications such as the transfer of LH2 from a ground storage tank to the rocket vehicle propellant tank, or through a rocket engine feedline during engine startup.

Observational Seismic Fragility Curves for Steel Cylindrical Tanks

The evaluation of seismic vulnerability of atmospheric above ground steel storage tanks is a fundamental topic in the context of industrial safety. Depending on the shell portion affected, on the extent of damage, and on toxicity, flammability, and reactivity of stored substances, liquid leakages can trigger hazardous chains of events whose consequences affect not only the plant but also the surrounding environment. In light of that, the study proposed herein provides an analysis of the seismic fragility of cylindrical above ground storage tanks based on observational damage data. The first phase of this work has consisted in collecting a large empirical dataset of information on failures of atmospheric tanks during past earthquakes. Two sets of damage states have then been used in order to characterize the severity of damage and the intensity of liquid releases. Empirical fragility curves have been fitted by using Bayesian regression. The advantage of this approach is that it is well suited to treat direct and indirect information obtained from field observations and to incorporate subjective engineering judgement. Different models have been employed in order to investigate the effects of tank aspect ratio, filling level, and base anchorage. Moreover, the effects of interaction between these critical aspects are included in fragility analysis. The hazard parameter used is the peak ground acceleration (PGA). Seismic fragility curves obtained from the described procedure are compared to those available in the technical literature.

Blending in above ground storage tanks with side-entering agitators

The blending of fluids in large, above ground storage tanks is widely practiced in the petroleum industry yet there have been very few studies of this mixing operation. The most demanding application is found when the tank contents have been allowed to stratify creating a light and heavy layer. The blend time in this case is defined as the time taken for the density of the fluid to become axially homogeneous.Wesselingh (1975) measured blend times using brine and water to produce the heavy and light layers and measured conductivity changes to assess the blending process. He only looked at one propeller geometry but did study the effects of several important geometrical system properties, such as the ratio of propeller to vessel diameter and liquid depth to vessel diameter.The study reported here uses Wesselingh’s technique but examines the blending performance of four commercially available propellers. The results show that the Advanced Pitch propeller sold by Philadelphia Mixing Solutions Ltd. and Mixing Solutions Ltd. is significantly more efficient than the competitors’ propellers when compared based on energy usage.These results, and Wesselingh’s, show that there are two operating regimes which are separated by a critical Froude number, FrC. At high Froude numbers (Fr>FrC) the dimensionless blend time is constant, and at lower Froude numbers (Fr<FrC) the dimensionless blend time is inversely proportional to Froude number. The implications for scale-up in both regimes are discussed.

Brittle fracture assessment of the API specification 12F shop welded flat bottom tanks

Above ground storage tanks (AST) are essential equipment in the oil and gas industry. In general, large field erected steel storage tanks have been studied and evaluated to understand their behavior under different loadings and identify possible design flaws. However, deep research is necessary to improve the operation of shop-built storage tanks.Particularly, API 12F storage tanks are commonly used in the upstream, exploration, and production segments of oil and gas projects. The environmental conditions of these projects will depend on their locations and might be harsh and threatening for the equipment operation. This paper investigates the brittle fracture failure of the API 12F shop-welded tanks. An elastic stress analysis using finite element models was developed to determine the response of these equipment to extreme environmental conditions and the API 579 “Fitness-for-Service” rules were implemented to perform the brittle fracture assessment.A brittle fracture evaluation is conducted to inquire the propensity of a material to fail without appreciable plastic deformation. In case of the API 12F tanks, several parameters such as ambient temperature, residual stresses, and material toughness can play significant roles in the behavior of the equipment. Complete 3D models of the current API 12F shop-welded, flat bottom tanks as well as axisymmetric and solid submodels were created to address the brittle fracture evaluation and determine whether these storage tanks can operate safely under extreme conditions. Through-wall and surface crack flaws were considered in the most critical joints of the storage tanks and toughness relative ratios between the response of the steel material and the acceptance criteria of the API 579 standard were calculated to describe the behavior of the equipment.

Storm surge fragility assessment of above ground storage tanks

This study proposes a dual layer metamodel based approach to develop parameterized fragility functions for above ground storage tanks (ASTs) subjected to hurricane induced storm surge. ASTs are extensively used in petrochemical facilities for storing large volumes of hazardous substances. Failure of ASTs due to storm surge may lead to spills that can cause severe environmental damage and considerable economic loss. A significant number of ASTs are located in coastal areas which are susceptible to hurricanes, such as in the Houston Ship Channel, Texas. However, tank design guidelines are deficient in addressing prevention of surge related failures. Although their vulnerability has been exposed during past hurricanes, the literature lacks studies on performance analysis of ASTs during storm surge events. In this light, a method is presented to derive fragility functions for the most important failure modes of ASTs – flotation and buckling – in addition to the system fragility, considered as series system of failure modes. For this purpose, a novel dual layer metamodel based approach is proposed where a limited number of simulations are used to train the first binary classifier, which predicts failure of tanks, upon which the second metamodel is trained; the final metamodel is used to derive parameterized fragility functions. This approach significantly reduces the number of limit state evaluations, which may require costly finite element simulations, and enables accurate fragility assessment to capture the nonlinear behavior of tanks under surge loading, while also considering the correlation between failure modes during system fragility modeling. Results indicated that the fragility estimates of a typical tank obtained with the dual layer metamodel compare well with those derived by high fidelity methods such as Monte Carlo Simulations. In order to demonstrate the application of the parameterized fragility functions to study the effect of variation in design and construction parameters, fragilities of four case study tanks are evaluated. The results highlight the effect of parameter variation on the fragilities and offer insights into the influence of alternative design impacts on tank vulnerability. For example, anchoring tanks significantly reduces the probability of flotation; however, anchoring leads to buckling dominated failures.

Performance evaluation on ground loading systems of cryogenic propellants

AbstractTo study and compare the merits and demerits of different ground loading systems for cryogenic propellants, three kinds of schemes have been classified according to their loading status: boiling point loading scheme, subcooled direct loading scheme and subcooled cycled loading scheme. Aiming at the three kinds of schemes mentioned previously, related mathematical models of ground storage tanks, filling pipelines and launch vehicle tanks are established by means of a thermal resistance analysis method, lumped parameter method and one‐dimensional finite difference method. Based on the thermodynamic analysis, a K‐T decision‐making method is adopted to determine the preferred scheme. Meanwhile, application situations of multiple ground loading systems in different countries have been analyzed in detail. The researches show that the boiling point loading scheme is the best choice in the aspect of comprehensive performance. However, the subcooled cycled loading scheme is preferable to the case of payload as design objective for the long‐term development. The classified schemes proposed in this paper reveal the feasibility and practicality in actual application of ground loading systems of cryogenic propellants. The study also provides theoretical basis and technological support to design or improve the ground loading systems of cryogenic propellants in the future. © 2017 Curtin University and John Wiley &amp; Sons, Ltd.

Rooftop level rainwater harvesting system

Unfortunately, in Lebanon and other countries in the Middle East region, water becomes scarcer than ever before, and over the last decades the demand on domestic water has increased due to population and economic growth. Although rainwater harvesting is considered to be a safe and reliable alternative source for domestic water, the inconvenience or impracticalities related to the cost and space needed for the construction of ground or underground storage tanks makes this practice not widely common in rural areas and rarely implemented in urban cities. This paper introduces a new technique to rainwater harvesting which can be easily used in both rural and urban areas: it collects and stores rainwater directly in tanks already installed on building roofs and not necessarily in special ground or underground ones. If widely adopted in Lebanon, this technique could help in: (1) collecting around 23 MCM (70 % of the current deficit in the domestic water supply) of rainwater and thus increasing the available water per m2 of building by 0.4 m3 per year, (2) saving around 7 % of the amount of electric energy usually needed to pump water from an aquifer well and ground or underground tank, and (3) considerably reducing the rate of surface runoff of rainwater at the coastal zones where rainwater is not captured at all and goes directly to the sea.

The Observation of Rainwater Harvesting Potential in Mahasarakham University (Khamriang Campus)

Rainwater harvesting from roof is considered as valuable water resources. Material Flow Analysis (MFA) of water in Mahasarakham University (Khamriang Campus) shows that rainwater harvesting from roof can reduce water supply production by 7% and save more than 200,000 Bt/year for water treatment cost. The sensitivity analysis suggests that by 5% water supply conservation and 20% additional rainwater harvesting, MSU could have enough water resources. The rainwater is suitable to be substituted water for gardening due to the convenience to assemble an above ground storage tank or a pond to store harvested rainwater from roof. The current practice of rainwater is collected and discharged into drainage system and treated in wastewater treatment plant. Utilisation of rainwater harvested could reduce wastewater amount that must be treated by 9%. Rainwater harvesting and reuse should be promoted in campus in order to encourage sustainable living and water conservation policy.

Some distinctions of LNG above ground storage tanks and recent developments of construction procedures in countries outside of Japan (mechanical parts)

Some distinctions of LNG above ground storage tanks and recent developments of construction procedures in countries outside of Japan (mechanical parts)