Superior Tank Installs Innovative Bolted Tank

Superior Tank Co., Inc. (STCI) is proud to have provided the new bolted steel tank for the Cauayan City Water District in Isabela Philippines. The bolted tank is the first of its kind in Northern Luzon and highlights the benefits of a bolted steel tank. The epoxy coated tank provides storage of 79,000 gallons of potable water for Cauayan City and is dedicated to the late Governor Faustino N. Dy and his son Governor Benjamin G. Dy. Their vision and initiatives have resulted in the development and modernization of the Cauayan City Water District and also contributed to the City being branded as “Ideal City of The North”.

The bolted steel tank used for the project was designed and manufactured to provide the city decades of service. Constructed of high strength carbon steel, the bolted tank is constructed for maximum durability and longevity. To meet local building codes and to withstand typhoons, the bolted tank is designed to meet a 200 mph wind load requirement.  To accommodate the city’s future needs and save the city time and money, the bolted tank was designed to be easily expandable by simply adding rings to the tank.  To survive the warm and humid conditions of the Philippines, the epoxy bolted tank features a corrosive resistant powder coating with an additional Silica-Zirconium(Si-Zr) underseal. To resist the harsh sun and UV rays, the exterior of the bolted tank was protected with specially formulated TGIC powder coating.  Our Sky White color was selected to reduce the solar heat gain which helps to keep the water cooler and preserve water quality.  In addition, bolted tanks manufactured by STCI are different than bolted tanks from other companies as it includes a steel floor.  The steel floor ties the shell together and prevents leaks and water loss which can occur with concrete bottom tanks.

The bolted steel tank in Cauayan City is truly an investment in the community and a testament to the vision of Governor Faustino N. Dy and Governor Benjamin G. Dy.

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What makes a bolted tank “Superior”?

Various companies sell bolted steel tanks, but there is only one “Superior Tank”. Is there really a difference between bolted tanks manufactured by Superior Tank Co., Inc. (STCI) and bolted steel tanks and glass-lined bolted steel tanks made by other companies? The answer is in short “yes” for various reasons including STCI’s precise manufacturing processes, premium raw materials, extensive company history, API SPEC Q1 / ISO 9001:2008 certification and outstanding customer service.
Superior Tank Co., Inc. is one of the few bolted tank manufacturers in the United States and the only bolted tank company with manufacturing facilities in both California and Texas. Owning and operating State-of-the-Art manufacturing facilities gives STCI complete control of the quality of our bolted tanks and we are not reliant on outside companies for the quality of our bolted steel storage tanks. All of our bolted tanks use quality materials such as heavy duty Grade 5 or Grade 8 high tensile strength bolts and the steel used for our bolted tanks is verified to meet specific quality standards such as surface quality, edge quality, silicone content, squaredness and flatness. In addition, our specially formulated powder coating and corrosion preventing SiZr seal maximize the lifespan of the epoxy coating of the bolted tank. Our heavy duty gaskets ensure our bolted tanks remain in service and do not require storage tanks to be taken offline to replace the mastic which is used with glass-fused-to-steel bolted tanks. We have invested heavily in precision equipment such as CNC machinery, Automated Robotic Technology (ART), and advanced turret punches to ensure our bolted steel tanks are manufactured with exacting precision. As our bolted steel tanks are crafted with such accuracy, components fit together perfectly, eliminating tank leaks and field rework.
To confirm our bolted tanks meet or exceed quality standards, STCI has implemented various Quality Management Systems and is API SPEC Q1 / ISO 9001:2008 certified. Various processes and procedures have been put into place to ensure our bolted steel tanks meet customer expectations and delivery schedule. In addition, STCI has earned the reputation of providing exceptional customer service and ensuring our customers are happy with their new epoxy coated bolted tank. The results of these extra efforts are illustrated in our excellent Customer Satisfaction rating and customer testimonials.
When all of these factors are considered, it is evident what makes our tanks, “Superior”.

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This is NOT your Father’s Bolted Steel Tank…


Bolted steel tanks have been used for storage for many years and some older tanks are in use today.  Since the first bolted tanks were put into service decades ago there have been numerous advances in their design and construction.

Modern bolted steel tanks are designed differently than from tanks 30 years ago.  Bolted steel tanks are now designed using 3D modeling software, increasing the speed and accuracy of the process. Select projects are designed using simplified Building Information Model (BIM) software which encompasses the entire project from design to manufacturing then installation. The BIM system can store beneficial ancillary information such as weight and dimension of components and materials used to build the tank.  Design standards such as the AWWA D103 have improved over the last several decades resulting in longer lasting and better performing tanks.  In addition, new tanks are more structurally sound thanks to advances in seismic and wind design methods.

In addition to tank design, the manner in which bolted steel tanks are manufactured has progressed. Originally, steel tanks were manufactured by fabricating raw material by hand or with basic equipment. Small variations in the individual components led to leaks as parts did not fit together properly. Today, bolted steel tanks are precision fabricated using specialized machinery in State of the Art factories. CNC automated machinery ensures extreme accuracy and reduces the fabrication time.  Tank accessories are joined together using robotic welding equipment for 100% perfect joints. In addition, by earning ISO 9001:2008 Certification and following strict procedures, manufacturers can guarantee product consistency and quality.

Innovative options such as factory powder coating have significantly increased the longevity of bolted steel tanks.  The powder coating application process includes spraying a SiZr liquid seal to the prepared steel. The powder coating is applied dry to the steel in an environmentally controlled area to eliminate surface imperfections. The coating is electrostatically applied for 100% coverage without runs, drips and voids. Powder coating formulas are now specially designed for the application; epoxy coating on the interior for continuous emersion and TGIC Polyester on the exterior for outstanding resistance to UV exposure. Once the powder coating is thermoset using mild temperature ovens, it chemically reacts with the steel to form a permanent bond. As all steel components including inaccessible areas such as the underside of the tank bottom are sealed with powder coating the entire tank structure is protected against corrosion.

The hardware used with modern bolted steel tanks has also improved since bolted tanks were first used. To ensure maximum durability of bolted steel tanks, new nut and bolt options were introduced. Encapsulated nuts and bolts are best suited to specific uses and protect against hardware corrosion.  In other applications, hot dipped galvanized nuts and bolts are the best alternative. In addition, the strength of the hardware has increased and bolts used today have a tensile strength of over 120,000 lbs per square inch and now Grade 5 and Grade 8 bolts are used in place of Grade 2. Such advances in tank design, manufacturing processes and materials allow bolted steel tanks up to 3,500,000 gallons to be built.

A final significant improvement which has improved the longevity of bolted steel tank is the introduction of heavy duty synthetic gasket material which is used in place of putty mastic. New gasket material such as ethylene propylene diene monomer (EPDM) is specifically formulated for storage of potable water, wastewater and even brine water.  The thick gaskets are precisely fabricated to fit into the seam between the steel tank panels and provide decades of leak free service. The gaskets remain flexible and therefore they are able to prevent leaks even as the steel expands and contracts due to temperature fluctuations and seismic movement.

When all of these advances are considered, it is easy to see how modern bolted steel tanks are very different than your Father’s Bolted Steel Tank.

EPDM, Viton or Buna-N Gaskets – What’s in a name?

Bolted Storage Tank, Storage Tank Gasket, Bolted Tank, Bolted Steel Storage Tank When purchasing a Bolted Steel Tank from Superior Tank, customers have several choices of gaskets. We offer three different premium gasket materials for our steel storage tanks: EPDM, Viton or Buna-N. Selecting the proper gasket material can make a significant difference in the lifespan of the tank.

EPDM (ethylene-propylene-diene-monomer) is a specially designed synthetic rubber for water applications. The general operating temperature for EPDM is -70 to 300 degrees Fahrenheit making it well suited to most water storage applications. In addition to outstanding water resilience, EPDM is very resistant to damage caused by heat, compression, sunlight, acetones, alkalis and ozone. However, it is not recommended for use with acids or hydrocarbons.

Similar to EPDM, Viton is also an elastomer with high yield strength for outstanding durability. Viton is manufactured by DuPont and is specifically formulated for use with most hydrocarbons including corrosive liquids such as crude oil and biodiesel. However, Viton is not recommended for storage of ketones and organic acids. It is also very resistant to compression, heat, acids, alkalis, ozone, sunlight and salt solution. With this tolerance to many harsh liquids and a very wide temperature range of -15 to 400 degrees Fahrenheit, Viton can be used with almost all steel tanks and most storage applications. Viton has years of proven success in the field and provides outstanding durability.

Buna-N is another option when outstanding resistance to oil, hydrocarbon and chemicals is required. Buna-N tank gaskets are comprised of a synthetic rubber copolymer and are very well suited to storage of crude oil and other petrochemicals. When storing ketones, esters and aldehydes in steel tanks, other gasket material is recommended for better longevity. Buna-N gaskets for steel tanks can withstand lower temperatures ranging from -40 to +212 degrees Fahrenheit.

We have found using a formed gasket instead of putty or mastic provides significantly better tank longevity. All gaskets used by Superior Tank are formed to a precise thickness to fit between bolted steel tank panels and remain flexible for many years. The high yield strength of the gaskets ensures they do not tear or leak when the steel expands and contracts with temperature variations. The gasket is a solid material and will not ooze or creep out of place. Our precision manufacturing process places bolt holes in the exact location to prevent bunching up or over stretching of the gasket resulting in leaks. In addition, bolt holes in the gasket are intentionally slightly smaller than the bolts to eliminate gaps and prevent leaks.

The cost of gaskets will vary depending on the material selected and the width required by the tank design. The bolted steel tank experts at Superior Tank can provide guidance regarding the best gasket material for your application and the liquid stored.