When buying a water storage tank, the configuration and selection process often is something that needs to be done in the early stages of project design. To apply for and secure funding that may be available, timing of construction and overall project costs will play a factor in the determination. Because many municipalities have a single source of water storage, the tank design plays a crucial role in meeting the current and future needs of a community.
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Some of the key details essential to the ultimate selection of the tank configuration process are an assessment of community demands for current and anticipated water supply, site conditions, pressure requirements, long-term maintenance, ease of access and overall costs.
There are three types of liquid storage tanks available that are considered for municipal water storage applications: glass-coated bolted steel, welded painted steel and concrete.
1. Design & Configurations
Standpipes, reservoirs and composite elevated tank (CET) designs are the different types of configurations used when selecting glass-coated bolted steel tanks. Standpipes are tanks where the water is elevated in a tall column to achieve gravity-fed pressure, which is required to properly feed the system. The tank height is greater than the tank diameter. The elevation of the water is accomplished by storing the required “water on top of water.” Standpipe height usually does not exceed 140 ft.
The most common configuration used for water storage is the reservoir. Reservoirs have a greater diameter than height and can be used with a pumping system or can be gravity fed. The width of these tanks can reach 250 ft with capacities up to 6 million gal. Similar to standpipes, the CET design is used in applications where height is used to achieve the head pressure needed to properly operate the system. The CET column is constructed in a hollow concrete pedestal on which the tank is then built. Structural rebar and steel embedded in the concrete reinforced walls that can exceed 10 in. thick and a top cap of concrete 4 ft thick.
There is plenty of space offered in the interior of the concrete pedestal for municipal maintenance equipment, pump stations, office space and other uses. The CET design does not have height restrictions and capacity can be as great as 1.5 million gal.
Depending on the diameter, snow loads and other factors, the roof of glass-bolted tanks can vary. They can be a free-span aluminum geodesic dome, consisting of panels mounted on a rigid structural frame, or the same glass-fused-to-steel material.
The tank floors usually are constructed with reinforced concrete or they can be glass-coated panels depending on site and design conditions.
2. Manufacturing Process
The technology and manufacturing process of this equipment sets these tanks apart from painted steel or concrete structures. When using the factory manufacturing process, the uncontrolled variables are eliminated, unlike field manufactured products such as painted steel or concrete tanks. Worker experience and extreme climatic environmental conditions that are proven to have a significant effect on in-field manufactured products have minimal effect on the glassing process. In addition, the tanks can be erected year-round as the manufacturing is completed in the factory and only the assembly of the components is required in the field.
3. Coating
All storage tanks have a coating. The coatings available today consist of either paint, concrete or glass. The impermeability and features of glass offer advantages.
The glass coating process begins with a glass frit that is mixed with other minerals and water to create a liquid slurry. This glass slurry is then robotically sprayed at precise amounts and thicknesses onto previously cut and rolled, punched, grit-blasted and cleaned steel sheet panels. Companies like CST run panels through a furnace at ° F. This heat melts the silica glass slip into the surface of the grit- blasted steel. This completes the mechanical bond, as well as the chemical bond between the steel and the silica glass.
Different coatings that are available for other tanks rely on a mechanical bond of the coating to the underlying material. The chemical bond strength is many times the holding strength of the conventional mechanical bond and prevents any undercutting of the coating, which can allow spreading of corrosion on the primary steel material. This benefit can best be explained by imagining a scratch on an automobile. Because that coating only has a mechanical bond, if the steel is exposed, corrosion will occur. Left untreated this corrosion will expand and creep beneath the surrounding painted surface and compromise the remaining coating.
This often is witnessed with raised bubbles, spreading rust and weakened substrate. The chemical bond of the glass-fused-to-steel coating prevents this spreading of corrosion in the event the coating were compromised.
With the goal of making the storage tanks as maintenance free as possible, companies like CST manufacture rounded sheet edges to exact radii to ensure adherence of the glass for complete encapsulation on all four sides of the sheet.
4. Tank Construction
A jacking system is used when erecting a glass-coated bolted steel storage tank. Once the starter sheet (bottom ring) is either embedded into the concrete foundation or constructed utilizing a glass-fused-to-steel floor design, the top ring of the tank is constructed on the jacks. The roof of the tank then is erected and the ring and roof are jacked up. Each additional ring is then assembled below the top ring by bolting the sheets together and applying a urethane sealant between the seams.
Tanks are assembled from the top down allowing for a safer and faster construction environment. The erection process normally is completed within a week or two, which saves costs to the owner if prevailing wages for onsite labor are being used. Additionally, the manufacturer requires that all building crews be factory-trained and certified in the erection process, ensuring quality control in the field.
5. Maintenance/Life Time Value
Glass-coated bolted steel tanks have a long lifetime. Glass coating never needs painting because it is permanent. Glass-coated tanks often are placed in areas, where long-term pleasing visual appearance is sought. The budgeted dollars that may be used to repaint a painted tank or repair aged concrete can be saved and funneled to other projects in a municipality.
6. Flexibility
The bolted design and erection of this product yields flexibility. Because manufacturing is completed in a factory, large staging areas needed when a product is manufactured onsite are eliminated. The construction of the tank typically can be completed with a cleared area of roughly 6 to 10 ft around the tank diameter. This small footprint can save thousands of dollars on the overall project beyond the price of the tank itself. The panels themselves can be hand-carried and easily assembled without cranes or special equipment, allowing this tank to be installed in many locations that would be impossible for other tank types.
7. Expandability
The glass-coated bolted tank design allows the tanks to be vertically expanded. If a community or industry experiences growth and additional capacity is necessary, the tanks’ jacking process allows the end-user to gain capacity quickly and cost-effectively. The factory-trained professional building crew unbolts the bottom ring from the original starter sheet, jacks the tank up and adds the number of rings necessary to achieve the new capacity. When these tanks are expanded, there is no difference in appearance between the original panels and the new panels.
Conclusion
Initial construction costs, anticipated life and long-term maintenance costs are significant factors relative to the various tank designs and materials available today. The long-term maintenance costs and life cycle during a tank evaluation all must be considered when selecting the appropriate product for a specific project.
Because project financing can vary depending on several factors, a complete analysis of initial costs and, lower maintenance should help a community decide which type of product is best suited for its needs.
In the evolving landscape of sustainable energy solutions, biogas digesters have emerged as a pivotal technology for converting organic waste into renewable energy. Central to the efficiency and durability of these systems are the tanks that house the digestion process.
Among the various options available, Glass Fused to Steel (GFS) tanks and Glass Fused Bolted Steel (GFBS) tanks are gaining attention for their unique combination of materials. This comprehensive guide explores the advantages and disadvantages of GFS and GFBS tanks, providing valuable insights to help you make informed decisions for your biogas projects.
Glass Fused to Steel tanks are engineered by fusing glass to steel surfaces, creating a robust and corrosion-resistant barrier. This fusion process enhances the durability of the tanks, making them suitable for various industrial applications, including biogas digestion. The fusion not only improves the structural integrity of the tanks but also ensures that they can withstand the harsh environments typically associated with biogas production.
One of the primary benefits of GFS tanks is their superior corrosion resistance. Biogas production involves the breakdown of organic materials, which can release corrosive substances like hydrogen sulfide and other acids. The glass layer acts as a protective barrier, preventing these corrosive agents from damaging the steel structure. This significantly extends the lifespan of the tanks, reducing maintenance costs and downtime.
The fusion of glass fused to steel results in a tank that combines the strength of steel with the resilience of glass. This makes GFS tanks highly durable, and capable of withstanding both internal pressures from gas production and external physical impacts. The robust construction ensures that the tanks remain intact and functional over extended periods, even in demanding operational conditions.
In biogas digester applications, maintaining hygiene is crucial to prevent contamination and ensure the efficiency of the digestion process. The glass surface is non-porous and smooth, making it easy to clean and sanitize. This reduces the risk of microbial contamination and facilitates regular maintenance, thereby enhancing the overall performance of the biogas system.
While functionality is paramount, the aesthetic aspect of industrial equipment should not be overlooked. GFS tanks offer a sleek and modern appearance, thanks to the glass's smooth finish. This can be particularly beneficial for facilities where the equipment is visible to clients or visitors, contributing to a professional and high-quality image.
Glass fused to steel tanks exhibit excellent resistance to a wide range of chemicals commonly encountered in biogas production, including acids and alkalis. This chemical resilience ensures that the tanks maintain their integrity and performance even when exposed to aggressive chemical environments, providing a reliable solution for long-term biogas operations.
The advanced manufacturing process involved in fusing glass to steel results in a higher initial cost compared to traditional steel tanks. This investment might be a consideration for smaller operations with limited budgets. However, the long-term benefits, such as reduced maintenance and extended lifespan, can offset the higher upfront expenses.
Producing GFS tanks requires specialized equipment and expertise to ensure the proper fusion of glass and steel. This can limit the availability of suppliers and may lead to longer lead times for manufacturing and delivery. Ensuring that you work with experienced manufacturers is essential to achieving the desired quality and performance.
While the glass layer provides significant protection, it is not impervious to all forms of damage. Physical impacts or stresses beyond the design specifications can potentially crack or chip the glass, compromising the tank's integrity. Proper handling and installation are crucial to minimize the risk of damage during transportation and setup.
Thermal expansion differences between glass and steel can pose challenges in certain environments. Fluctuations in temperature may cause the materials to expand or contract at different rates, potentially leading to stress points or micro-cracks over time. Addressing these considerations in the design phase is vital to ensuring the longevity of GFS tanks.
Glass Fused Bolted Steel (GFBS) tanks incorporate bolted connections, offering additional flexibility and ease of maintenance. These tanks combine the benefits of glass fusion with the practicality of bolted steel construction, making them a popular choice for various industrial applications.
The bolted connections in GFBS tanks allow for easier disassembly and reassembly, facilitating maintenance and repairs. In the event of glass damage or other issues, individual sections can be replaced without the need for complete tank replacement. This modularity enhances the overall maintainability of the tanks and reduces downtime.
GFBS tanks offer greater versatility in installation due to their bolted design. They can be assembled in different configurations to accommodate varying space requirements and operational needs. This adaptability makes them suitable for a wide range of biogas digestion setups, from small-scale installations to large industrial systems.
The bolted connections provide a level of structural flexibility that welded tanks may lack. This can be advantageous in environments where tanks are subject to shifting loads or dynamic forces. The ability to adjust and reinforce connections as needed contributes to the overall resilience of the system.
Bolted steel tanks allow for more customization options compared to monolithic welded tanks. Manufacturers can tailor the design to meet specific client requirements, including size, shape, and additional features. This customization ensures that the tanks align perfectly with the operational needs of the biogas facility.
Contact us to discuss your requirements of glass fused steel tanks. Our experienced sales team can help you identify the options that best suit your needs.
While bolted connections offer flexibility, they also introduce potential points of vulnerability where leaks can occur. Ensuring that all connections are properly sealed and maintained is essential to prevent gas or liquid leaks, which can impact the efficiency and safety of the biogas system.
GFBS tanks require precise engineering and construction to ensure that the bolted connections remain secure under operational stresses. This complexity can lead to longer construction times and necessitate skilled labour, potentially increasing the overall cost and timeline of the project.
The combination of glass and steel, along with the additional hardware required for bolted connections, can result in heavier tanks compared to some other materials. This increased weight may require more robust support structures and can impact transportation and installation processes.
Bolted connections require regular inspection and maintenance to ensure their integrity. Over time, bolts can loosen due to vibrations or thermal cycling, necessitating periodic tightening or replacement. Failure to maintain these connections can compromise the tank's performance and safety.
When deciding between GFS and GFBS tanks for biogas digestion, it's essential to consider the specific needs and constraints of your project. Here's a comparative overview to aid in your decision-making process:
FeatureGlass Fused to Steel (GFS)Glass Fused Bolted Steel (GFBS)Corrosion ResistanceExcellentExcellentDurabilityHighHighMaintenance EaseModerateHighInitial CostHigher than traditional coatingsHigher than traditional coatingsCustomizationLimitedHighPotential for LeaksLowHigher due to bolted connectionsInstallation FlexibilityLowHighRepairabilityLowerHigher due to modular designFor larger projects with higher budgets, the added benefits of GFBS tanks, such as ease of maintenance and customization, may provide significant value. Smaller operations might prefer the straightforward durability of GFS tanks if initial costs are a primary concern.
Assess your ability to perform regular maintenance and inspections. GFBS tanks require more frequent attention to bolted connections, which may necessitate trained personnel and a structured maintenance schedule.
Consider the environmental factors where the tanks will be installed. If your facility experiences significant temperature fluctuations or dynamic loads, the structural flexibility of GFBS tanks may offer better performance.
Evaluate the long-term costs associated with each tank type, including maintenance, potential repairs, and replacement. GFS tanks, with their robust corrosion resistance, may offer lower lifecycle costs despite higher initial investments.
Proper installation is crucial to maximizing the benefits of Glass Fused to Steel and GFBS tanks. Here are some best practices to ensure optimal performance and longevity:
A medium-sized agricultural biogas plant opted for Glass Fused Bolted Steel tanks due to their ease of maintenance and customization options. The facility required tanks of varying sizes to accommodate different stages of the digestion process. The modular design of GFBS tanks allowed for seamless expansion as the plant scaled up its operations. Regular maintenance procedures ensured that the bolted connections remained secure, resulting in consistent biogas production and minimal downtime.
An industrial waste management facility chose Glass Fused to Steel tanks to handle high volumes of corrosive waste. The exceptional corrosion resistance of GFS tanks prevented degradation of the steel components, even when exposed to aggressive acids and hydrogen sulfide. The durable construction reduced the need for frequent replacements, leading to significant cost savings over the tank's lifecycle. Additionally, the smooth glass surfaces facilitated easy cleaning, maintaining high hygiene standards.
The field of glass-fused tank technology is continually advancing, with ongoing research aimed at enhancing performance and reducing costs. Future developments may include:
Engineers and industry professionals all over the world are opting for glass-fused-to-steel tanks. These defect-resistant storage tanks will give decades of trouble-free operation in difficult conditions. But, tanks glass fused do need to be built using this unique glass-fused-to-steel technology and controlled for the highest quality by ISO certification.
When well manufactured, porcelain-enamelled tanks never need recoating.
While steel, aluminium, cast iron, copper, and brass can all be used as glass coating substrates, porcelain enamelled tanks are made of steel. The type of steel used is usually determined by the tank's size requirements. The larger tanks may need a tougher grade of steel.
But only purchase from manufacturers who offer ISO certification, which entails more than 16 standard examinations before units are approved for sale. Glass Fused to Steel tanks are ideal for the containment of potable, municipal, agricultural, and industrial fluids because of their low maintenance requirements and inherent resistance to contamination.
The top GFS Tank suppliers and erectors provide a full service, from foundation installation through sidewall erection and roof construction.
When compared to in-situ cast concrete options, tanks are typically constructed in a week or two, including roofs or domes, saving the owner significant money on onsite labour expenditures.
Tanks are supplied flat-packed to the construction site for simple transport and handling.
The main components of the kit are the glass-fused-to-steel panels, which are ready to bolt together and include any custom cut-outs for nozzles, manways, and other accessories as needed.
Building crews educated and certified in the erection process are provided by the leading firms, ensuring the same level of quality control in the field as in the factory. The panels are bolted together and sealed with a high-performance seal that is appropriate for the substance being stored.
To protect the bolt heads from corrosion in the process environment, they are all plastic-capped.
The bolt head seals the shank and protects it from contact with process fluids by squeezing mastic between the panels.
For the building of these tanks, only properly trained erectors should be used. This isn't something that can be accomplished efficiently with general on-site labour.
Selecting the appropriate tank type is a critical decision that impacts the efficiency, safety, and cost-effectiveness of your biogas project. By carefully evaluating the pros and cons of Glass Fused to Steel and Glass Fused Bolted Steel tanks, you can choose the solution that best aligns with your operational needs and long-term goals.
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Ready to enhance your biogas digestion system with top-of-the-line glass-fused tanks? Our expert team is here to guide you through the selection, installation, and maintenance process. Contact us today to discuss your project requirements and discover how our Glass Fused to Steel and Glass Fused Bolted Steel tanks can optimize your renewable energy operations.
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Liquid storage tanks are available in a variety of forms and capacities ranging from hundreds to millions of gallons to fulfil the most demanding storage requirements. GFS tanks or tanks glass fused are the most popular single tank type.
Many biogas plant experts do say that Glass Fused to Steel Tanks are a good choice for CSTRs and many other “wet process” anaerobic digestion process operations.
In fact, no other tank can compete with this one when it comes to holding aggressive liquids like digestate or wastewater, since the tank covering is resistant to chemical attacks that would otherwise destroy and ruin other tanks.
While both options come with their own set of advantages and challenges, understanding their unique characteristics ensures that you make an informed choice tailored to your specific needs.
Embrace the future of sustainable energy with glass-fused tank technology and propel your biogas projects to new heights of success.
[First published on 20 September . Updated March .]