Glass Fused to Steel Tanks is the most common tank specification for CSTR biogas digester reactor tanks. In this article, we discuss their pros and cons.
Enamel tanks, GFS tanks (GFtS), and Glass Fused Bolted Steel (Porcelain Enameled) tanks are all terms used to describe this type of tank.
It is essential that all anaerobic digestion tanks must be extremely durable, which means they must be resistant to corrosion as well as impact and abrasion. These tanks have that characteristic but as in most things, their advantages come with a few disadvantages. Read on and find out what those pros and cons really are.
Advantages of Glass Coating to Steel Technology
The premium coating technology in the storage tank industry is without doubt glass-fused-to-steel. Glass Fused to Steel tanks are widely utilised in bio-energy (especially CSTR biogas plants), municipal sewage, landfill leachate, and industrial wastewater treatment, among other applications.
How Hard Can It Be to Choose a Suitable Tank Material?
Isn't it supposed to be simple to pick a liquid storage tank? It's a liquid-holding tank. Is there really that much of a difference?
The truth is that all types of tanks have advantages and disadvantages, and the only way to choose the finest product is to measure their advantages and disadvantages against your demands.
Tanks Made of Glass Fused to Steel
Glass-fused steel (or enamelled steel) bolted tanks are a premium breakthrough technology that is engineered for long-term performance with absolutely minimal maintenance.
These tanks are not only the most preferred tank material for biogas digesters because they combine the toughness of steel with the corrosion resistance of glass. They're also ideal for storing potable water, wastewater, industrial chemicals, bio-digesters, sludge, and dry bulk materials, among other things.
Enamel frit (glass compounds) is chemically fused with steel sheets in a state-of-the-art furnace at very high temperatures (800 – 1,000 degrees C) to generate an integrated porcelain-like coating that is securely bonded, chemically inert, and impermeable to liquids.
Suppliers quote these tanks as having a range of 140°F at 3-11 pH which they can withstand without corrosion.
They also have a long track record of proven performance, with tens of thousands installed globally for municipal and industrial uses over the past 65 years.
Advantages of Glass Fused to Steel Tanks
The strength and flexibility of steel are combined with the remarkable corrosion resistance of glass in glass fused to steel liquid tanks. This has a number of advantages over traditional epoxy coated or welded painted storage tanks, including:
- Outstanding anti-corrosion properties
- In the factory, fast installation is combined with high-quality design, production, and quality control.
- Safe and skill-free: The operator has no need for long-term worker training, and as there is virtually no maintenance for the plant owner his operatives spend less time working aloft.
- Local weather has a negligible effect on these tanks
- Low initial investment – particularly relevant for biogas digesters and for industrial wastewater treatment projects
- Low-cost maintenance and easy-to-repair
- Low life-cycle costs from this lifetime coating
- Possibility of relocating, expanding, and repurposing
- They look good in a choice of colours
- Much easier to clean than unlined equipment
- Each tank is tailored to the particular application.
Even stainless steel tanks, while normally an ideal material for these tanks, cannot withstand the high sulphur which may accumulate at the top rim of commercial digester tanks.
Glass Fused To Steel Tank Disadvantages
It's not all good news when considering Glass Fused To Steel Tanks. The drawbacks are not large, but worth noting as follows:
- Joints, where the GFS Tank is bolted down to the concrete base slab that serves as the tank's base, must be carefully designed and sealed to avoid leaks developing
- Physical damage, such as being hit by a crane when moving other sections of the digester, such as pumps, may cause the glass coating to chip off at the point of impact
- A competitor technology is concrete vs steel biogas tanks for Anaerobic Digestion Plants where concrete provides much better insulation. Generally, concrete digester tanks do not need thermal insulation and this avoids the costs of adding a layer of insulation around GFS Tanks.
- If the tank must be buried or partially buried, a steel tank is typically less suited to the soil loads that this imposes than a reinforced concrete walled tank
- Make sure that the GFS tank you buy has edge corrosion protection as they are bolted steel tanks. Unless the panel edges are also coated there may be a long-term problem.
However, all of the above issues can be prevented by following excellent design, installation, and operation practices.
In temperate countries, digester tanks are generally covered with thermal insulation material and on the outer edge, plastic-coated aluminium profile sheeting. The reason that this is done is to protect the insulation once installed. This also shields the tanks from accidental impact damage to the fused-to-glass-enamel while they're in use.
The Main GFS Tank Disadvantage can be Initial Cost
All the pros we have mentioned are great, but, the most significant disadvantage of GFS tanks can be their cost. Glass-lined tanks are often much more expensive than epoxy tanks.
As a result, many businesses may, at first sight, think that they will be unable to afford the upfront fees. However, it's worth looking into the total cost of ownership over the tank's lifetime, as maintenance costs are reduced and they don't need to be changed as frequently with a GFS.
Quality Assurance and Standards for Glass-Fused-To-Steel Bolted Tanks
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 9001 certification.
When well manufactured, porcelain-enameled 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.
Delivering Quality Glass-Fused-to-Steel Tanks
But only purchase from manufacturers who offer ISO 9001 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 to their low maintenance requirements and inherent resistance to contamination.
Erection of Bolted Steel Panels and the Construction of a Base Slab
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.
The Ultimate Flat Pack!
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.
Bolt Head Protection
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.
Bio-Energy GFS Tanks Conclusion
Liquid storage tanks are available in a variety of forms and capacities ranging from hundreds to millions of gallons to fulfill 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.