When making the decision to purchase an above ground storage tank (AST), size and location aren’t the only things to consider. In fact, they’re not even the first. Before you decide how big you want the tank to be or where you want it to go, you need to decide what material it’s to be constructed from.
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While concrete, polyethylene, and bolted steel tanks each have their own benefits; welded steel tanks are the best overall choice. Not only do welded steel tanks last longer than the others, but their lifetime cost is lowest and they require the least maintenance.
Stainless steel tanks are highly resistant to the effects of corrosion and other natural elements like heat. In fact, stainless steel is so resistant to rust and corrosion that internal and external coatings aren’t even needed to protect the base metal. Stainless steel also remains ductile through all temperature ranges, is fire resistant, and is unaffected by exposure to UV light, which can damage paint and other coatings. That being said, properly maintained welded steel ASTs can have an expected lifespan of over 100 years, whereas bolted steel tanks only survive around 30.
Going hand in hand with longevity is durability. Unlike concrete tanks that are prone to cracking and leaking, welded steel tanks are leak-free. This is important, because not only can a crack jeopardize the integrity of a tank’s structure and make for an expensive, lengthy repair but, also, if a crack is left untreated, moisture will collect, bacteria can form, and the sanitation of your stored goods is compromised. In addition, bolted steel tanks also pose a danger, as every bolt on the tank represents a potential point of weakness. With welded steel, tanks are stronger, maintenance is lower, and repairs are easier.
With welded steel tanks having a longer life cycle and requiring much less maintenance, the total cost of ownership (TCO) of a welded steel AST is often lower than its bolted steel and concrete counterparts over the long term. Don’t just take our word for it though, check out the Steel Tank Institute’s TCO tool, and see for yourself.
With different jobs requiring tanks in different shapes and sizes, wouldn’t it make sense to build a tank to your own needs, rather than buy one pre-fabricated to someone else’s? With welded steel tanks, you can design ASTs to be virtually any height or diameter, with multiple roof styles, paint schemes, and other architectural elements to choose from as well.
As mentioned before, stainless steel is resistant to corrosion and leaking, making it the ideal storage tank for water. While concrete storage tanks can leach calcium into water supplies if not coated correctly, stainless steel tanks will keep the water clean and unaffected. It should come as no surprise that hospitals are required to use stainless steel tanks for this reason. Finally, not only is stainless steel 100% recyclable, but over 50% of new stainless steel comes from re-melted stainless steel scrap, greatly reducing the environmental footprint left behind.
Before you buy your next AST, consider these points and weigh your options. We’re sure you’ll agree welded steel tanks are a cut above the rest.
Want to increase your welded steel tank’s longevity AND durability? Check out our free tip sheet, “The #1 Way To Save Your Water Storage Tank’s Interior.”
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Rotolining, or rotational lining, is a technology that allows engineers to bond thermoplastic polymer to the interior of tanks, vessels, pipes, pipe fittings, and other types of process equipment. The resulting layer of polymer adds corrosion protection and resistance to chemicals.
The rotolining process
Rotolining is applied via a rotational process. Workers place granulated powder resin inside the vessel or similar process equipment, seal all its openings, and then mount the vessel inside an oven. The oven rotates on two perpendicular axes at low rpm, giving the resin time to melt and spread uniformly over all interior surfaces of the equipment. The rotation of the oven causes the polymer to mold itself to the interior shape of the vessel. The treated equipment is slowly cooled to prevent shrinkage and warpage. Upon cooling, the polymer provides a seamless, permanently bonded liner.
Depending on the polymer used and the equipment’s service application, the thickness of a rotational lining ranges from 0.09 inches to 0.45 inches, thicker than most lining alternatives. A thick lining provides more corrosion and abrasion protection and maximizes service life of the equipment.
What is the difference between rotational lining and rotational molding?
In rotational molding, powdered resin is put into a mold, heated, and rotated on two axes to force the melted resin onto the sides of the mold. After cooling, the mold is removed, resulting in a hollow part formed out of the selected material. Rotational molding is commonly used to produce both industrial and consumer goods.
Rotational lining (or rotolining) is a similar manufacturing process. A pipe, tank, or other process vessel is supplied as the starting point, rather than a mold. The polymer is used to line the vessel and left intact.
Why use rotolining?
There are multiple benefits of rotolining solutions.
Because the lining is monolithic and seamless, there are no weld joints to act as potential points of failure.
The structural integrity of the equipment is maintained and even enhanced.
Rotolining provides a seamless transition to a flange, making flanges easy to seal and reducing the risk of leaks.
No other lining technique offers as wide a range of materials, allowing the material to be matched to its application
Fully bonded liner can withstand vacuum and eliminate annular space for permeation to collect and condense.
Operating temperatures are allowed through the full temperature range of the material chosen for the liner.
Rotolining is suitable for a wide range of metallic substrates.
Limitations of rotational lining
A with any technology, there are situations in which a different solution would be better. Here are three limits of rotolining.
Because the rotolining process requires the equipment to be mounted inside an oven, application is generally limited to
straight lengths of pipe up to 20 feet long and vessels that will fit within a 12-foot sphere.
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Another limitation is that some internal structures, such as large baffles, are difficult to line.
Unlike lining sheets, which can be installed in the field, rotolining must be added at the factory.
Rotolining is limited to application on metal, including aluminum and carbon steel.
Polymers used in rotolining solutions
Polymer linings are selected depending on the application. Many polymers can be melt-flow processed including olefins, nylons, and fluoropolymers. A variety of these thermoplastic polymers may be selected to achieve the needed levels of chemical resistance, abrasion resistance, and corrosion resistance protection. Common materials for rotational lining solutions include:
ETFE (Tefzel)
PFA (Teflon)
PVDF (Kynar)
HDPE (high-density polyethylene)
One innovative material from RMB is HDPE blended with a biocide to deter the growth of biological films that can lead to microbially influenced corrosion when seawater is the process fluid. Over time, build up can even cause fouling of process lines, leading to costly maintenance
Proper polymer selection takes into account the compatibility of the material with the chemicals expected in the application. Other selection criteria include the material’s ability to bond with the substrate, its temperature performance, and of course, cost. The broad array of options allows engineers to tailor the lining to fit the needs of the application. Ultimately, the ideal selection of material will maximize the life of the treated equipment and reduce maintenance costs.
These materials must be formulated to enhance their ability to bond with surfaces. Teflon, for example, doesn’t want to stick to anything, so coupling agents are added to enhance adhesion. To prepare a surface for receiving a lining, the metal substrate must be clean and shot blasted to achieve a near white state. A clean and microscopically rough surface promotes mechanical bonding of the polymer to the metal.
What are the alternatives to rotolining?
When adding protection to process vessels and equipment, engineers commonly use sheet lining, powder coating, dual laminate construction, fusion-bonded epoxy (FBE), and loose linings of PTFE (polytetrafluoroethylene). Many of these have disadvantages.
Sheet liners and dual laminate liners have weld joints that create potential points of failure. Also, they have pressure limits and temperature limits lower than those of rotolined materials.
Compared to powder coating, a rotational lining is much thicker, reducing the chance of liner failure, and extending service life, especially in abrasive applications.
A rotomolded liner is tightly bonded to the substrate, in contrast to liners that are applied with adhesive. This makes rotolining useful under most vacuum services.
What’s more, powder coatings and dual laminate liners are not easy to repair, usually requiring the equipment to be removed from service.
Rotolining works well on complex interior shapes where powder coating is difficult and where a sheet liner may be difficult to install.
Fusion-bonded epoxy (FBE) is similar to rotolined polymers in that both materials bond with the metal substrate and create a seamless lining. However, FBE is limited to 0.04-inch lining thickness, and its application (similar to the application of powder coating) may be difficult inside equipment with complex geometries. FBE may be less costly, but often it provides a service life that is one-third that of rotolining, making the total cost of ownership far higher.
How Can RMB Help You?
Whether you are trying to minimize downtime because of a failed liner and need emergency services, need help to replace an asset during a future outage or are planning a new build, RMB can help. Simply reach out with your equipment type, service stream and dimensions and we’ll help you determine what solution best fits your needs.
When considering storage solutions for water and wastewater treatment, three key factors are usually prioritized: cost-effectiveness, safety, and long-term profitability. Glass-Fused-to-Steel (GFS/GLS) tanks have become the go-to choice for industries seeking reliable, high-performance storage with proven financial and operational advantages.
Many projects focus only on initial purchase costs, but the real game-changer is the lifetime cost of the storage solution. Unlike concrete or welded steel tanks, GFS tanks require minimal maintenance, have a longer lifespan, and eliminate the need for expensive protective coatings and recoating cycles. Over decades of operation, these savings add up, making GFS tanks a financially sound investment for municipalities and industrial facilities alike.
Time is money, especially in large-scale infrastructure projects. GFS tanks are modular and can be assembled 3-5 times faster than traditional tanks, reducing labor costs and allowing facilities to become operational sooner. This means quicker revenue generation and improved cash flow, which is crucial for private investors and public-sector projects aiming to minimize financial risk.
Industrial operators cannot afford safety risks or compliance failures. GFS tanks offer superior resistance to corrosion, chemical exposure, and extreme weather conditions, making them a low-risk, high-security investment. Their non-porous, glass-coated surface also prevents contamination, which is critical for drinking water storage and wastewater treatment applications where regulatory compliance is non-negotiable.
Unlike traditional storage solutions, bolted GFS tanks can be disassembled and relocated without compromising structural integrity, adding to their long-term asset value. This is particularly beneficial for industries with evolving operational needs, such as wastewater treatment facilities that must scale up or relocate due to regulatory changes.
For companies in water and wastewater treatment, choosing GFS tanks isn't just about storage—it’s about making a strategic investment in cost efficiency, operational safety, and long-term profitability. By reducing maintenance costs, ensuring regulatory compliance, and expediting project timelines, GFS tanks help industries maximize their return on investment while delivering essential water and wastewater services efficiently.
If you're looking to optimize your next project, now is the time to explore GFS technology.
If you’re interested in learning more about Glass-Fused-to-Steel technology or have specific storage/treatment needs, feel free to reach out! Let’s discuss how we can help you find the perfect solution for your storage requirements. Your support is my biggest motivation! (folded hands)
If you are looking for more details, kindly visit gfs Water Storage Tanks.