CST tanks are the premier choice for liquid and dry bulk applications because they are backed by unparalleled service and maintenance. The tank in question stores soda ash which is used as a buffer to reduce pH levels. A buildup of excessive pressure had caused the tank to bulge at the top, which damaged the shell at the top and the deck.

The tank is situated snugly inside a building with less than two feet of clearance on the sides and just under seven feet of clearance at the top. Add in the fact that the client wanted to add three feet of capacity to the tank and this was going to be no ordinary repair job, but CST was up to the challenge.

CST developed a turnkey solution that required little or no intervention by the client. Workers disassembled the damaged panels and other tank components and removed them by hand through a roof access. They also brought in new components through the roof, and working in the cramped space not only replaced the damaged panels and deck, but also attached three feet of additional panels at the top, as well as replacing other customer equipment.

CST’s experienced personnel supervised each phase of the project – from initial approval to project completion – so the client could concentrate on maintaining uninterrupted service.

“We work with tank owners to develop maintenance management programs that are custom designed to meet the specific needs of their facility,” says Tom DeDonder, Vice President of Construction & Services. “When we’re intimately familiar with a customer’s tanks and how those tanks work in the context of their operations we can not only respond to the tough challenges but anticipate the type of maintenance a tank will require and foresee potential problems down the road.”

Your tank is an investment in the safe and reliable operations of your facility. Get the peace of mind that you deserve from the proven industry experts. From technical inspections through dedicated turnkey project management and execution, CST Services’ highly responsive team provides you with options customized to meet the short and long term demands of your business to maximize the value and life cycle of your investment.

The post CST Eases the Pressure With Turnkey Maintenance Solution appeared first on CST Industries.

“Great customer communication is one of the most important parts of the process that leads to ultimate project success,” says Zurliene. “CST works closely with many long-term clients like our valued client Ferrara, providing critical turnkey services for NFPA 652 compliance including testing, design and construction services.”

After all, the candy-loving public will not wait.

The post CST Helps Iconic Candy Company Mitigate Dust Danger appeared first on CST Industries.

Structural Issues – Identification of metal loss or thinning of steel

There are several factors that contribute to metal loss in a steel tank, such as corrosion or wear from abrasion.  Often it is not obvious or visible from the outside of the tank and an internal inspection or ultrasonic thickness (UT) testing may be required.  Metal loss or reduced metal thickness may impact the structural integrity of the tank and in many cases can lead to dents, buckling, or bulges in the tank. Metal loss can also lead to holes in the tank which threatens product contamination, reduced product quality, product loss, or even loss of profits. Holes also lead to moisture ingress into the tank, which may accelerate corrosion, further reducing the integrity of the hardware or welds. At its most dangerous, substantial metal loss will impact the structural integrity of the entire tank and may lead to catastrophic silo failure and jeopardize personal safety of employees or other individuals. A proper inspection will identify at-risk areas in your tank to avoid aggressive metal loss.

Ensuring Best Operational Performance

The performance of your tank relies on proper operational procedures.  While that seems obvious, there are often overlooked indicators that the tank is not operating efficiently.  Proper venting is the most critical element because a tank needs to maintain the ability to “breath” as product goes in and out of the tank.  Pressure relieve valves, bag houses, bin vents or other ventilation equipment that are not properly cleaned or maintained can become plugged up and lead to over-pressure or excess vacuum on a tank during normal operations and deposit product on the roof around the vent.  Abnormal pressures can cause structural damage such as cracks in the steel, settlement of the roof, denting or severe buckling of the sidewall.  Ultimately, if not corrected, this may lead to excessive build-up of product on the roof or an accumulation of water which further overloads the tank, and ultimately may lead to structural failure. 

Improper flow of the stored product can also cause damage to a steel tank due to sudden changes in internal pressures due to rat-holing, bridging, arching or other abnormal conditions.  An indicator of potential flow issues is often hammer marks on the hopper.  When product is not flowing out of the tank properly, the tendency is to attempt to knock the material free at the hopper, but this is an indication that your tank is not performing efficiently.  The root cause is usually one of two things: the product has a high moisture content and is caking or not flowing properly, or the hopper angle is not sufficient for the product stored in the tank.  Proper inspection may identify these operational risks and determine scope of work needed, so it can be corrected before it becomes a problem.  However, in some scenarios it may be necessary to consult with a flow expert to correct the problem.

Increased Safety for Employees and Community – Regulatory requirements

There are three primary drivers for regulatory requirements: regulatory agencies, national codes and local jurisdictions.  Many regulatory agencies (OSHA, MSHA, etc.) require that owners inspect and maintain equipment in a safe condition to protect personnel and the community.  Codes (NFPA, FM, AWWA, etc.) also have minimum requirements for safe operation and compliance. Finally, in many cases local jurisdictions have adopted similar safety requirements.  In all cases, building owners are required to both know and meet the safety regulations related to the proper maintenance of their assets.  Regular inspections and maintenance can prevent incidents.

Extend Life of Your Tank with Preventive Maintenance

Inspections proactively identify signs of reduced metal thickness or improper operation conditions.  With proper and timely inspection and preventive maintenance, your tank will operate safely, and you will extend the life of your tank and avoid extensive and expensive rework later. A competent professional will see the warning signs through a thorough visual inspection. Also, always insist on a documented inspection report including a full summary of the tanks current condition with photographs and recommendations and cost estimates for any maintenance or work the tank may require. This will help with long-term budgetary planning.

When you have such a valuable and costly investment, there is no reason to allow less reliable sources to compromise your storage tanks integrity. In order to maintain the true integrity of your storage system, it is important to utilize OEM parts and services. As the original equipment manufacturer, we have your best interest, always. Companies like CST have always serviced tanks and domes upon request but have also advanced their maintenance program to ensure all customers receive OEM-quality parts and services from CST and CST authorized professionals, such as the CST Authorized Dealer Network. Utilizing OEM parts and services significantly simplifies the proper care and maintenance process, because their services will strictly match the quality that you would expect from a competent professional.

Other Reasons

There are other reasons to perform an inspection as well. Some additional considerations include:

• To determine the suitability of the tank for continued or expanded service
• To lower overall life cycle cost
• To determine if a tank is suitable for a change in service (type of product stored, different flow characteristics, etc.)
• Determined if a tank should be replaced
• Perform Ultrasonic Thickness testing (UT) or other thickness testing to set baseline steel thicknesses

If you have numerous tanks across many facilities and regional operations, CST can also help you assess and prioritize all assets so you are focused on assessing and spending your maintenance budgets on the most critical needs in a timely manner. This starts with an initial assessment of the condition of all of your storage assets and ends with complete plan for you to implement that will guide you in budgeting and planning management of your assets for the next several years. If you do not know where to start with your tanks, we can help with that also.

CST Industries is the global leader in the manufacture and construction of factory coated metal storage tanks, aluminum domes and specialty covers. CST’s global network includes manufacturing facilities and technical design centers and multiple regional sales offices that are located throughout North America and the United Kingdom. International offices are in Argentina, Australia, Brazil, India, Japan, Mexico, Panama, Singapore, United Kingdom, United Arab Emirates and Vietnam. Currently, more than 350,000 storage tanks and 19,000 covers have been installed in 125 countries throughout the world.

The post Storing Dry Bulk Plastics? Here’s Why You Should Have Routine Tank Inspections appeared first on CST Industries.

Pressure relief system panels around the top of a silo can help alleviate pressure and avoid combustible dust explosions.

Published in the November 2019 issue of Powder and Bulk Engineering

Combustible dust hazards exist in many bulk solids industries, and a dust hazards analysis can help you pinpoint potential trouble spots. This article first describes the basics of conducting a dust hazards analysis and then explains storage tank venting system options that can be used to mitigate those hazards.

Keith McGuire, CST Industries, Inc. and Brian Edwards, Conversion Technology, Inc

Any combustible bulk solid — and even some normally non-combustible solids when reduced into small enough particles — can cause an explosion when certain concentrations and conditions occur. When small material particles are in suspension the material tends to burn (oxidize) very quickly.

There are five factors needed for a combustible dust deflagration or flash-fire to occur: fuel (combustible dust), oxygen (typically in the air), an ignition source (heat), confinement, and dust dispersing into a cloud. If all these factors come together in a contained area, and the building, storage tank, or compartment doesn’t have the strength to contain the resulting pressure, a combustible dust explosion can occur.

For dust to become explosive, it requires a concentration at or above its minimum explosible concentration (MEC), which is the minimum amount of dust that will explode when dispersed in air. These concentration levels can accumulate in process equipment such as bins, storage tanks, conveyors, air–material separators (cyclones, baghouses, bin vents), ductwork, and other spaces. With all five factors present, the dust can ignite in the confined space, causing a relatively minor explosion. This disturbs and disperses the accumulated dust, creating a dangerous dust concentration in that space. The first fire acts as the ignition source for a secondary explosion, which uses the dispersed dust for fuel, and often can be much larger and more destructive than the initial deflagration.

Conducting a DHA

The severity of the hazards present in a facility are influenced by a number of factors. These include the nature and quantity of dust, the equipment configuration, the equipment’s materials of construction, the facility layout, the existence of ignition sources, and the proximity of the hazards to employees and other structures. A dust hazards analysis (DHA) is a systematic analytical study of a given facility and its components and processes to identify potential combustible dust hazards. Conducting one can help you identify and mitigate trouble spots.

Specifically, NFPA 652: Standard on the Fundamentals of Combustible Dust, requires that a DHA include the following:

• Identification and evaluation of locations or processes throughout the facility where potential fire, flash-fire, or explosion hazards exist.
• Identification and evaluation of specific fire and deflagration scenarios where these hazards exist.
• Identification of safe operating ranges of processes and equipment, such as flow rates, temperatures, etc.
• Identification of any safeguards that are in place to mitigate the fire or explosion hazards.
• Recommendations for additional safeguards where needed

In a DHA, a detailed review of each process component and building or area where combustible dust is handled, generated, or present is conducted.

The first step is to identify the components and areas to be included in the DHA. This can be done by reviewing process and facility drawings and by touring the facility. For each component and area included in the DHA, the person conducting the analysis must determine the potential for a hazardous atmosphere to be present and identify operating conditions that could result in a hazardous atmosphere. These should include normal operating conditions, start-up/shut-down conditions, and potential upset conditions.

Next, all potential ignition sources should be identified for each process component. Potential ignition sources can include open flames, electric devices, static electricity, mechanical impact and friction, hot surfaces, hot work, powered industrial trucks, and others. Based on the configuration, design, and interconnectivity of an area or process component, deflagration and explosion scenarios and their impact should be identified.

The next DHA step is to identify any current safeguards — explosion protection, deflagration isolation, ignition source control, dust control, housekeeping — in place to mitigate combustible dust hazards.

Once all this data has been compiled, a risk characterization should be conducted. If the risk characterization finds that the risk level isn’t acceptable, recommendations for additional risk-reducing safeguards need to be provided.

Mitigating storage equipment hazards

The DHA must be completed or led by what NFPA standards define as a qualified person who has demonstrated the ability to understand combustible dust and its associated hazards through education or experience.”  i.e., someone knowledgeable of the science of dust fires and explosions as well as the specific hazards of the process being reviewed.

If the qualified person determines that your process equipment requires additional safeguards to reduce the risk, there are mitigation options. According to Dr. Chris Cloney, director of DustEx Research, a consulting company that focuses on combustible dust safety, 37 percent of deflagration events occur when conveying bulk solid materials to storage and in storage tanks, and 24 percent occur in bin vents.

Evaluating the stored material’s specific properties is important when determining the potential severity of a tank, vessel, or bin vent deflagration. This includes understanding the material’s specific nature and properties, including factors like Kst (deflagration index for dust) and Pmax (deflagration pressure). Using these two factors, along with the principles of NFPA 68: Standard on Explosion Protection by Deflagration Venting,  a qualified engineer can calculate Pred (maximum pressure developed during venting). With this information, a silo can be designed with enough strength to safely operate during an overpressure event. This likely will require incorporating one of two common pressure venting relief systems into the storage equipment to provide explosion protection.

The first venting system involves explosion panels, which are independent relief devices located in the air space or head space of a tank and designed to burst at a determined pressure. Using NFPA 68 equations and given the Pstat (vent release pressure), you can determine the quantity and size of explosion panels needed. These devices also can be installed on bin vents or other equipment where emergency venting may be necessary. Note: Make sure the explosion panels are oriented away from any staff access areas or other system components.

The second venting system is a weak-seam deck, also referred to as a frangible roof, where the roof-to-shell joint or connection is designed to separate and release pressure through the top of the tank. When using this system, consideration must be made to be sure that no other weight or restrictions are added to the top of the deck that may limit its proper operation.

Both types of systems have their benefits and limitations depending on the application, the process equipment location, the physical layout and constraints of the tank, the building, and the surrounding areas.

Other possible modifications

Once the type and specifics of the pressure relief system have been determined, they can be incorporated into a tank’s design. This can be done relatively easily for new tanks and facilities but can become more difficult when retrofitting an existing tank or process equipment. There are many factors to consider in this situation; primarily, what is the required operating volume?

If there’s sufficient storage capacity, the quickest and easiest method is to install the explosion panels directly into the existing tank shell. This can be done by field-cutting openings in the tank shell and installing the requisite frame to connect the explosion panels. The material storage level must remain below the explosion panels, so if the panels are placed in the top of the tank shell, the effective storage volume will likely be reduced. Depending on the physical characteristics of the environment, several options exist to maintain the volume.

• The existing tank may be modified by removing the upper portions of the tank and replace them with new explosion panels pre-installed in a new tank shell including a new roof. If the present tank volume needs to be maintained, the tank height must be increased to accommodate keeping the product below the explosion panels. The condition and design of the tank requires evaluation prior to any structural and deflagration venting modification.
• Second, placing explosion panels in the tank’s roof may be possible. This depends on venting proximity to a safe environment, personnel access on and around the top of the tank area, and enough space in the roof to locate the panels.

In some instances, modifying the tank by raising it to allow for outside venting through the building structure or envelope might be possible, or ductwork could possibly facilitate safely exhausting the pressure outdoors. Other considerations may include adding stiffening or other reinforcement to the tank to resist the venting pressures.

Remember, when dealing with explosive dusts in your equipment and facility, consulting with qualified professionals and experts who have the knowledge and industry experience to identify and implement specific solutions is important.

About the Author

Keith McGuire, PE, is the structural engineering director for CST Industries, specializing in the design and fabrication of bolted and welded storage tanks, silos, and accessories. He graduated from Pittsburg State University with a degree specializing in structural, mechanical, and civil engineering and is active in numerous industry standards committees including API, AWWA, ASME, and NFPA.

Brian Edwards, PE, is the director of engineering for Norcross, GA-based Conversion Technology. He has a degree in civil and environmental engineering from Georgia Tech and has more than 20 years of experience as a consultant to industry. He has worked on various NFPA committees, including being a principal member on the committee for NFPA 61.

The post Identifying and Mitigating Combustible Dust Explosion Hazards in Storage Equipment appeared first on CST Industries.

Published in the October 2019 issue of WE&T Magazine

Water is a precious resource. If it’s mishandled the results can be devastating from an environmental and financial standpoint. When you operate a wastewater treatment facility near the Pacific Ocean, the stakes are even higher.

The Encina Wastewater Authority is based in Carlsbad, California and serves over 400,000 residents and regulates approximately 600 businesses in a 125 square mile service area of northwest San Diego County.

The Authority takes its mission seriously: to deliver cost-effective services to its patrons and act as good stewards of the natural environment. Careful forecasting and planning go into every capital expenditure so Encina’s facilities operate at maximum output with a minimal footprint.

Water that isn’t recycled for irrigation and other non-potable uses is discharged into the ocean. According to the Authority, “high treatment-plant reliability is essential for protecting the Pacific Ocean, which ensures that anyone visiting local beaches enjoys a fishable and swimmable marine environment. Furthermore, protecting the ocean and the recreational use of beaches is essential to maintaining the region’s economy and quality of life.” That’s a big responsibility.

Over the years, Encina has upgraded its elaborate network of tanks, treatment systems and pumping stations with an emphasis on performance, safety and aesthetics. The facility has eight 35’ x 300’ aeration basins, where organic material in wastewater is broken down by activated sludge containing microorganisms. Each basin requires a secure cover that will prevent odors from escaping, is safe for operations and maintenance staff and also pleasing to the eye.

When it came time to upgrade the aeration basins, capital projects manager Jimmy Kearns remembered the positive experience the Authority had with CST, the worldwide leader in the design, manufacture and construction of custom aluminum covers and structures for architectural, environmental and industrial applications.

“Our first experience with CST was on the rehabilitation of an influent junction structure,” says Kearns. “We were impressed with the look and feel of the CST cover system, the quality and overall experience.”

Kearns continues, “The old covers on the aeration basins, dating back to 1982 and 1992, had exceeded their useful life. Water had infiltrated, they were UV damaged and unsafe.”

Additionally, Encina’s design consultant, Carollo Engineers, had engaged with CST on numerous successful aluminum cover projects at facilities across the country. Carollo project manager Jeff Weishaar, PE, embraced the challenge of working with CST and Encina’s operations, maintenance and safety staff to custom-design the covers and other appurtenances for the aeration basins to meet Encina’s needs. Kearns recommended that the Authority engage CST to custom design aluminum covers for each of the eight aeration basins.

CST has supplied over 19,000 covers in more than 90 different countries and offers multiple structural, high-strength aluminum design solutions including domes, extruded flat covers, formed flat panel covers, truss supported covers, as well as custom products specifically designed for unique vertical and overhead applications.

Encina’s facility is in a high visibility location – bounded by the I-5 freeway, beachfront residential property and several small businesses – which means every component of its treatment system must be pleasing to the eye and odor-free.

Safety is also a key issue. Like any employer, Encina has restrictions on the amount of weight that can be lifted by staff, so Kearns and the engineering team put a lot of thought into how easily the cover system could be handled.

“One of the advantages of the CST cover system is the cost associated with the manual effort of removing and replacing it,” says Kearns. “With the old covers, for removal, staff were required to wear a full body fall harness, tied off to fall protection. Now when they need to conduct a visual inspection or access the basins to perform maintenance they can safely remove the covers from the outside of a guardrail perimeter. The reduction in injury risk and fall potential is huge.”

He continues, “It can look great from the designer’s or builder’s perspective, but it all comes down to the operator being able to work with the cover system on a daily basis. Ultimately, that’s the consideration.”

CST manufactures multiple designs that are engineered specifically for each installation to provide excellent odor control, protection from the environment and safety for operations personnel. Its extruded aluminum panel cover can be custom designed to meet specific functional and design loading requirements. All aluminum designs are constructed of 6063-T6 and 6061-T6 aluminum structural members to ensure quality, durability and longevity.

“Jimmy was looking for something aesthetically pleasing and functional for the staff and, most importantly, safe,” says Jeremy Neill, P.E., sales engineer and partner at Coombs-Hopkins, an authorized CST sales representative. “Our cover customers need ease of accessibility, and the CST design and fabrication team excels at creating the right solution for every situation.”

Like any custom installation on a project with multiple contractors and deliverables, there were challenges.

“We’d look at the basins and say they’re all the same dimensions but there were minor variations in the use of support beams and width of the covers,” says Kearns. “It was a tedious, time-consuming project from design to shop drawing through fabrication but Jeremy and CST rose to the occasion at every turn.”

CST Contact Information:

• 
  CST Industries, Inc.
  Edgar Saenz
  Regional Sales Manager
  310-353-5162
  esaenz@cstindustries.com
  

The post You Can Judge This Facility by Its Cover appeared first on CST Industries.

There are few things in this world that get better with age. Wine, maybe. But most things in life don’t withstand the test of time, like physical objects that are exposed to the elements. When thousands of customers are relying on clean, safe drinking water there’s little margin for error. What works today has to work just as efficiently 15 or 20 years from now.

Danny Lassiter knows the importance of reliable water storage. As Project Manager of the Gladeville Utility District in Tennessee, Lassiter continues to marvel at the dependability of Aquastore tanks. Gladeville has five Aquastore tanks and Lassiter says it’s impossible to tell the difference between the oldest tank, built in 1992, and one built in 2007. Both are used for potable water storage at the plant.

“After we put the second tank online in 2007 we took the old one offline for inspections and cleaning,” says Lassiter. “We drained it and the only thing we had to do was clean up some silt on the floor. The glass and bolts were in perfect condition.”

Lassiter has never had any problems with the tanks and figures maintenance on the older Aquastore has cost the district only about $200 over the last 15 years. It’s one of the main reasons why Gladeville now employs five Aquastore tanks for storage, with a sixth on the way.

The Gladeville water treatment plant was built in 1992. That’s when the district purchased its first Aquastore. Demand has grown steadily and a third well was drilled in 2017. Lassiter points out that the name of the aquifer, Beinshawee, comes from the Shawnee language, which means “big water” or “deep water.” The region was a well-known overnight stop for the Shawnee because of the availability of water and shelter. Later, the area was home of the largest tobacco plantations and horse farms in the South, due in large part to the water supply. 

It’s no surprise then that for generations, residents and businesses have counted on an abundance of water. And Gladeville Utility District delivers, thanks not only to Aquastore but also to the crew at Southeastern Tank, the area’s exclusive Aquastore dealer. Lassiter says they go above and beyond and do more than just service existing tanks.

“We have a concrete tank at Nashville Superspeedway which is out of service because the track is closed to competitive events,” he says. “Some light bulbs were burned out in a hard-to-access area and I called Shelly at Southeastern and asked if they’d change them out. She said no one had ever asked them to do that before but she’d be happy to.”

In fact, Southeastern Tank is located in the district and many employees, including CEO Dustin Dowdy, are customers.

“We are rural water through and through,” says Dowdy. “We offer systematic construction that is up to code and delivered on schedule, proactive and preventive care, the right accessory when you need it, and solutions to keep your water at optimal quality. Our goal is to deliver storage solutions that meet the needs of rural water systems at a price that meets their budgets.”

Gladeville Utility District serves parts of three counties in Middle Tennessee: Davidson, Rutherford and Wilson. The area is business-friendly and has attracted companies like of Amazon, Nissan and Starbucks, which have opened distribution centers. Lassiter knows as the district’s needs grow it can scale up quickly thanks in large part to Aquastore’s ease of construction.

Unlike other liquid storage tanks, an Aquastore tank is built with a series of mechanical jacks, which use a smaller footprint than traditional steel or concrete tank erection. First, the top ring of panels is assembled, then lifted up to make room for the next ring, and so on.

Aquastore’s glass-fused-to steel technology is the water and liquid storage leader – outperforming concrete, steel bolted and elevated tanks. More than 100,000 have been installed for numerous applications in over 70 countries around the world. It’s corrosion resistant and built to withstand the hot Florida sun, humidity and salt air, and retains its brilliant luster for decades, which means it doesn’t have to be repainted. Lifecycle costs are some of the lowest in the industry, with minimal maintenance required.

Last year Gladeville pumped over 700 million gallons of water to 7,000 customers, and it’s good to know that its storage needs will be met for decades to come.

Contact Information:

• 
  CST Industries, Inc.
  Sales
  844-44-TANKS
  sales@cstindustries.com
  
• 
  Southeastern Tank, Inc.
  Dustin Dowdy, CEO
  615-466-5220
  dustin@setank.com
  

The post Youth is Served: Gladeville Tanks Defy Age appeared first on CST Industries.

Published in the June 2019 issue of WaterWorld Magazine

Situated about 45 miles southwest of Tampa, Manatee County’s lush environment needs water to thrive, and prudent management of that water is essential. Officials take water management seriously, including the methods used to recycle wastewater for irrigation and other non-potable uses.

The County’s 5,300 reclaimed water customers include golf courses, parks and playgrounds, landscape areas, highway medians and rights-of-way, and farms. Other uses include toilet flushing and fire protection. About 62 percent of the wastewater generated in the County is reused in the reclaimed water system.

Manatee County has three water reclamation facilities that can operate at a combined capacity of up to 33.5 million gallons per day. The reclaimed water distribution system consists of approximately 943,276 linear feet (179 miles) of County-owned transmission mains, two booster pump stations, and one re-pump station. A 30-inch transmission main interconnects the County’s three service areas with smaller distribution mains within the service areas.

With so much riding on the performance of its water reclamation system, Manatee County turns to CST for its liquid storage needs. The relationship dates back to 2007, when the County replaced an aging welded steel tank at its North Water Reclamation Facility with a glass-fused-to-steel tank. That set a precedent for five additional tank purchases.

“One of the main reasons Florida Aquastore won the original bid is they were able to retrofit their tank to bolt onto our original concrete slab,” says Brent Laudicina, Lead Operator of North County WRF. “We were impressed with their flexibility because they did exactly what we asked instead of saying they can only do it one way.”

At six million gallons, Manatee County has the distinction of having the most storage provided by CST in the entire state of Florida. The County’s first storage tank measured 98’ x 19’ with a capacity of 1 million gallons and is used for sludge storage. In 2013 it replaced two more welded tanks with two glass-fused-to-steel tanks – also for sludge storage – and ordered three more in 2017 for storage of influent (raw sewage) as part of an upgrade of the facility.

“The consulting engineer Kimley Horn came to us and asked for a tank configuration that provided three million gallons of storage,” says Peter Boccagna, Sales Manager at Florida Aquastore for the State of Florida. “A tank of that capacity typically has a wide diameter and they had a narrow footprint to work with, so it wouldn’t fit. After discussions with the engineers, they decided to put in three 1 million gallon equalization tanks in a tight alignment and the result was a perfect fit.”

Boccagna knows space limitations eliminate certain types of tanks – especially those that have to be erected using cranes and other equipment. CST tanks can be built in close proximity to each other; in fact, the three equalization tanks sit just five feet apart from one another. Unlike other liquid storage tanks, glass-fused-to-steel tanks are built using a series of mechanical jacks that are safe and fast and allows the tank to use a smaller footprint than traditional steel or concrete tank erection. First, the top ring of panels is assembled, then lifted up to make room for the next ring, and so on.

“It’s cool to watch them go up,” says Laudicina. “Those tanks went up in two weeks, tops. Construction was simple and they made very few if any special requests of us.”

Glass-fused-to-steel tanks have been proven to outperform concrete, steel bolted and elevated tanks. Companies like CST have installed more than 100,000 for numerous applications in over 70 countries around the world. It’s corrosion resistant and built to withstand the hot Florida sun, humidity and salt air, and retains its brilliant luster for decades, which means it doesn’t have to be repainted. Life cycle costs are some of the lowest in the industry, with minimal maintenance required.

Laudicina also quickly learned about the CST tank’s adaptability when one was pressed into service for alum storage. Alum is used in processing of drinking water to promote coagulation of tiny particles as well as remove color and improve turbidity. The spent alum from the County’s potable water facility contains dirt and debris that had to be isolated from the clean, drinkable water.

“We had a lot of rain last winter and the drying beds were wet the whole time, which meant we ran out of storage capacity for the spent alum,” he says. “So, we called in tanker trucks, pumped the alum and hauled it to our plant and put it directly into one of the sludge holding tanks, then pressed it and hauled it to a biosolids dryer facility.”

A dependable tank is the anchor of every efficient liquid handling facility. AQUASTORE® proves its versatility every day, going the extra mile like helping Manatee County convert wastewater processing sludge into a Class AA biosolid, which it sells to local sod farms and orange groves for fertilizer.

Just looking at the tanks every day reminds Laudicina that his employer made the right choice.

“We can’t tell our oldest tank from the new ones,” says Laudicina. “They look amazing. The CST tank has a more contemporary look that gives the plant an overall look of sophistication.”

• 
  CST Industries, Inc.
  Kim Mathis
  Global Marketing Director
  713-351-3769
  kmathis@cstindustries.com
  
• 
  Florida Aquastore
  Peter Boccagna
  Sales Manager
  941-426-5151
  peter@florida-aquastore.com
  
  

The post Natural Wonders and Manmade Marvels appeared first on CST Industries.

Published in the June 2019 issue of Water Efficiency Magazine

On a “degree of difficulty” scale that’s a 10, the City of Calistoga services over 5,000 residents and shuffling three liquid tanks in a seismic zone without interrupting the water supply of an entire town, is one daunting task.

Derek Rayner has overcome plenty of challenges as deputy public works director for the City of Calistoga, CA, but nothing like the one presented by a 53-year-old seismically deficient steel welded tank that had clearly seen better days. For nearly 50 years, the aging tank serviced the city’s water supply by itself with little fanfare and even less maintenance.

“It was past due for maintenance but we really couldn’t drain it and take it completely offline to sandblast and recoat until another tank was built,” says Rayner. “Besides the expense and the need to take the tank offline, it would still need significant seismic retrofitting, which would be extremely expensive and difficult to do.”

In 2013, a new concrete tank was put in service, giving the city the flexibility to consider the fate of the 53-year-old tank.

The City had previously commissioned Kennedy Jenks to conduct a feasibility study to determine the best course of action: to retrofit or to replace the old tank. The study determined the existing tank was seismically deficient and included an analysis of maintenance and lifecycle costs of various tank types. When comparing those numbers to the cost of rehabbing the 53-year-old tank, the data was convincing. A new tank would cost slightly more than rehabbing the existing one, but when based on lifecycle costs it would cost less for the city to build a new tank, which would require significantly less maintenance over the long term.

The juggling act began after the Napa earthquake in August 2014, when Rayner started pursuing grant money to fund design and construction of a tank that would meet seismic requirements. The grant application was approved and the search was on for the right tank design.

Prior to his time in Calistoga, Rayner had worked for an engineering consulting firm and remembered conversations with a fellow engineer who’d built a glass-fused bolted tank in nearby Calaveras County. He revisited the idea and consulted California Aquastore, the exclusive provider of CST tanks in the region.

“We were impressed by the promise of minimal maintenance and low lifecycle costs of the Aquastore tank,” says Rayner. “Obviously there’s a large capital cost to install any new tank and in a perfect world you don’t want to have to budget to re-line and re-coat it in 10 or 15 years.”

In the end, the City of Calistoga chose an Aquastore^® tank because its glass-fused-to-steel system is developed to meet the demands of liquid storage for the long term. It’s resilient, requires minimal maintenance, has superior fire and seismic resistance and carries the lowest lifecycle costs. Unlike other bolted steel tanks, the Aquastore is virtually seamless, which reduces the likelihood of leaking from within or contamination from the outside.

Fabrication is a multi-step process:

1. A panel of high strength low carbon steel is blasted and alkaline cleaned.
2. The panel’s edges are beveled, and its surface sprayed with a steel alloy.
3. Next, the panel is sprayed with a specially formulated slurry that gives it durability, consistency and impermeability. Unlike powder coatings or paint, the slurry is inorganic so it blocks corrosion.
4. The panel is then fired at temperatures above 1,500° F to fuse the porcelain coating and the steel.
5. Tests are conducted to verify integrity and durability, including high voltage testing to detect discontinuities.

If the decision were this simple, Rayner could leave work on time every day. But living in an active seismic and fire hazard zone, he knows the ground could shake at any time and a tank that isn’t secure could crack, split or topple, leaving the city’s 5,273 residents with a compromised water supply.

The Napa earthquake of 2014 shook a large portion of northern California, and while Calistoga was 40 miles away from the epicenter and was spared the worst of it, Rayner had always believed that the integrity of the district’s infrastructure would one day be tested. That hunch was reinforced when the Tubbs wildfire burned in October 2017 and forced the evacuation of the entire town.

“We’ve been fortunate because the old tank had no foundation,” says Rayner. “It was just sitting on the ground, held in place by its own weight and the weight of the water inside, and highly susceptible to seismic failure.”

Fortunately, the city had authored a report on the substandard condition of the old tank, which it pulled off the shelf and submitted as evidence to win funding through a FEMA hazard mitigation program. The FEMA money was enough to pay 75% of the cost of the new tank, leaving only 25% of the cost to be picked up by the city.

With the funds allocated, the heavy lifting began. Knowing that the risk of earthquake called for an extraordinary solution, CST engineers set to work designing a tank to meet all applicable seismic codes. First, a large amount of data was imported into the company’s AQUA2 design software, including:

• Seismic site class
• Seismic accelerations at 1s and 0.2s
• Seismic importance factor
• Soil report

Multiple factors were considered, including hoop stress, axial stress, wind stress, seismic stress, hydro dynamic and bolt stress, which were compared against levels allowed by code.

Results from the analysis – including wind shear, wind movement, seismic shear, seismic movement, tank weight and height of the contents – were loaded into the model for the design of the tank’s foundation. Stresses underneath the foundation due to the load combination and overturning were compared with related safety factors, which helped determine the size, number and spacing of the rebar.

Despite the tank’s location in an active seismic zone, the greatest risk to its bolted all-aluminum geodesic dome is wind shear. The dome was designed to meet maximum required wind loads, which surprisingly exceeded seismic loads. CST’s flush batten OptiDome^® delivers superior stability, functionality and is aesthetically pleasing.

“Analysis revealed maximum wind reaction drag at a single dome support of 600 pounds and maximum seismic drag of 460 pounds,” says Eduardo Alonso, project engineer at CST. “Due to the low mass to volume ratio of the aluminum dome, seismic effects did not influence the dome design. Instead, applied wind loading on the large surface area on the dome results in the largest horizontal shear reactions.”

With so many variables, collaboration was key to a successful installation.

Says Rayner: “When you’re already working with a consulting engineer to prepare the preliminary designs, it’s important that the tank manufacturer can come in mid-process and you don’t feel any disruption. The entire process was seamless because of the working relationship between Kennedy/Jenks, CST and California Aquastore.”

The tank was shipped in sections from CST’s factory in DeKalb, IL to the site in Calistoga, where assembly was performed using a system of jacks. Porcelain enameled tanks are easier and less costly to assemble than welded or concrete tanks. Using a sidewall erection process, the glass-fused steel panels were bolted together, forming a ring. When completed, the ring was lifted with jacks and the next ring was assembled directly underneath. No crane was needed, therefore allowing erection crews to stay safely on the ground and the whole process took as little as four feet of space beyond the tank foundation.

Calistoga’s new tank sits on a concrete base and is fitted with seismic anchors which will keep it from overturning in case of tremors. All pipes connected to the tank are fitted with special joints that allow the pipe to move in any direction without breaking. A computer monitors the water level, chlorination levels and trihalomethane removal system.

“A tank purchase is a big line item and we like to see customers thoroughly vet their options because it means their ultimate decision is sound and data-based,” says Eric Harper, president and CEO of California Aquastore. “Derek had many options to choose from and he asked a lot of great questions, which I believe we answered to his satisfaction.”

The post Aquastore® Tank Delivers Excellent Seismic Resistance Capabilities appeared first on CST Industries.

With over 350,000 field proven storage tank installations in more than 125 countries and a diverse product portfolio that now includes pre-configured tanks, CST understands the benefits bolted tanks can offer and how pre-configured tanks can provide the best value in the shortest lead time.

Why are design specifications important?

Well written specifications ensure the customer receives a quality product that meets the requirements of the job, meet code and ensure all bidders adhere to the minimum requirements. This enables the purchaser to review bids that are as near equivalent as possible. It can also help to identify where bidders have made an exception to the specification that can be discussed in further detail.

Specific to storage tanks, the specifications that will have the largest impact on the tank design are the product being stored, including the specific gravity or density, followed by the maximum wind speed and the seismic zone for the region where the tank will be located. The design code will not only help determine the maximum design wind speed and seismic criteria that should be used in the design, but also determine how the loads are applied to the tank and the safety factors required.

To determine the proper design code, the storage application and applicable codes for the country where the tank will be constructed should be reviewed. Design codes that are most common for bolted storage tanks include AWWA D103, FM 4020, API 12B, and Eurocodes. If considering a pre-configured tank, check to make sure that the design code and storage application are compatible with the available tank designs. Normally, pre-configured tanks will target a market and specific storage application where the design codes are consistent and have the most overlap between countries. For this reason, it is important to understand the target market when considering preconfigured tanks.

Variety of sizes and appurtenances

Once the applicable design specifications have been determined, the storage volume, followed by the optimal diameter and height should be considered. If there are no constraints limiting available ground space, then being flexible with the tank dimensions will maximize the options and minimize the cost. A larger diameter and shorter height will generally reduce the price of the tank, but this price savings can be somewhat offset by the roof and floor, so it is important to consider alternatives.

Bolted storage tanks come with a wide variety of options, starting with the floor and roof. Floors are typically steel or concrete. In many applications (low seismic and good soil) concrete is usually the most economical choice, but steel can reduce the foundation cost in high seismic areas or regions with poor soil. Steel floors are also preferred for hazardous applications where the risk of leaks must be minimized. Typical roofs include trough deck, low profile, column supported, and aluminum domes. Trough deck roofs are the most economical, but if a sealed roof is required, a low-profile roof is a good option. Aluminum domes are ideal if minimal maintenance is preferred. When considering pre-configured tanks, the sizes of available tanks and roofs will be optimized to provide the best price in the shortest lead time and a customer that remains flexible will be best suited to take advantage.

Finally, appurtenances such as ladders, manways, level indicators, pipe brackets and nozzles should be selected. While options may be limited when it comes to appurtenances offered with pre-configured tanks, the appurtenances offered are focused on the needs of the specific storage application and market. If possible, being flexible with appurtenances will most likely lead to an optimal solution with the best lead time and price.

Why are coatings so important?

If properly specified, coatings improve the life cycle and value proposition of the storage tank; balancing price and economy for longevity and minimizing downtime. Not only is the coating important to consider, but the coating process can have a significant impact on the quality of the coating. Bolted tanks, whether pre-configured or custom designed, are factory coated in a controlled environment with state-of-the-art automation and the most stringent quality control processes. At a minimum, a bolted tank supplier should test the surface preparation, inspect for holidays, check adhesion, measure thickness, and confirm the color as part of the coating process. Additional quality assurance measures such as verification of the oven temperature and line speed are also commonly implemented.

Common coatings for bolted tanks include galvanizing, both liquid and powder epoxy, and porcelain enamel (aka glass-fused-to-steel). Within each coating type, there are several tiers that offer higher quality, and it is important to understand the coating that a specific storage application requires. Variables that can determine the best coating type for a specific storage application include storage temperature, pH levels, and any additives such as fats, oils and greases.

A supplier that can offer various coating types and tiers within each coating type is most likely to be able to provide the best product for a given application.

Not all tanks are the same

The type of storage tank and the method of construction should be carefully considered. Field welded, concrete, and bolted steel tanks are the most common types of storage tanks. While field welded and concrete share a large percentage of the global market, both have significant disadvantages when compared to bolted. Field welded tanks require skilled construction labor and specialized equipment; and have long construction lead times. They are also more susceptible to construction delays caused by weather and quality control issues due to weld testing and the field applied coating in a non-controlled environment leading to re-coatings and additional downtime.

In addition to some of the same challenges as field welded, concrete tanks are susceptible to hairline cracks that can leak, and biofilm growth due to the rough surface texture. With concrete tanks, some design standards allow a daily leakage limit of up to 0.5% due to the permeable / porous nature of concrete. Whether field welded or concrete, there are limited options for accelerated lead times through pre-configured tanks as the lead time is largely driven by the need for skilled labor and specialized equipment, in addition to engineering.

Bolted tanks not only offer shorter lead times and a superior coating but provide the most flexibility as the customer has the option to choose the method of construction that is best suited for the location and preference. Bolted tanks can either be designed as flat panel or API chime panel. Flat panel tanks are typically constructed from top-down with the use of construction jacks that allow crews to perform the bulk of the work at ground level. API chime tanks are scaffold-built from the bottom-up, eliminating the need for jacks. Other differences include how the bolted joints are sealed, API chime tanks use gaskets at the bolt seams, while flat panel tanks typically use sealant applied at the seams. The sealant type and gasket material can be changed to best suit the application. Both styles of bolted tanks have their advantages, depending on the tank size and resources available. Either type of bolted tank is suitable for pre-configured tanks, but the type and method of construction offered will be chosen based on the preferences of the target market.

Economical solution

Pre-configured bolted tanks can provide all the advantages of bolted tanks with additional advantages. Pre-configured designs allow the tank manufacturer to better anticipate inventory requirements and eliminate the need for custom engineering, allowing the manufacturer to share the benefits of cost savings with the end user. Pre-configured designs are best applied where there is less variability in what the market needs and the end user can remain flexible to take full advantage. Water storage applications such as municipal water, fire protection, and potable water, among others, are ideal uses for pre-configured tanks as these markets provide the most overlap in the requirements of the customers.

Delivery time

One of the primary advantages of bolted tanks is the lead time. Bolted tank manufacturers can offer significantly reduced lead times due to the advantages offered by manufacturing and coating the sheets in a controlled environment, without sacrificing quality. The sheets and tank components arrive on site ready to assemble without the need to pre-fabricate. Bolted assembly does not require skilled labor or specialized equipment, reducing the overall project timeline with a shorter construction lead time and less on-site costs. Bolted tanks can be engineered, delivered, and constructed within four months from time of order. Pre-configured bolted tanks can be delivered and constructed in 3 months from time of order by eliminating the need for custom engineering.

Are they competitive in lifespan?

Bolted steel tanks are just like field welded steel tanks, or any other steel structure, if properly maintained, they can seemingly last forever. However, if not maintained, factory coated bolted tanks will typically last longer than field welded due to the quality of the factory applied coating over a field applied coating. In addition, bolted tanks are easier to repair and upgrade when compared to field welded tanks or concrete tanks. For example, if there is sheet with coating damage, the bad sheet can simply be replaced with a new sheet that has been coated in a factory setting, eliminating the need to cut, fabricate, and weld a patch or develop any other type of expensive field fix. It is also common for flat panel, jack constructed tanks to be expanded by adding rows, providing the option to increase the tank volume as demand for storage increases.

Where should I start?

If you are in the market for a bolted storage tank, we hope that you find this information useful and will consider a pre-configured tank as we have found that they offer the optimal balance between quality, lead time, and price for most water storage applications. If you need a custom tank, CST has the largest product offering and options in the market, including premium epoxy and glass coatings.

For more information on Vulcan by CST storage systems call +1 844-44-TANKs or email sales@cstindustries.com

CST Contact Information:

• 
  CST Industries, Inc.
  Kim Mathis
  Global Marketing Director
  713-351-3769
  kmathis@cstindustries.com
  
• 
  CST Industries, Inc.
  Aaron Johnson, P.E.
  Director of Mechanical Engineering & New Product Development
  913-428-7158
  ajohnson@cstindustries.com
  

The post Are pre-configured bolted storage tanks a good fit for my application? appeared first on CST Industries.

Published in the May/June issue of Shale Water Management Magazine

The US is the world’s largest producer of natural gas and oil, thanks in large part to hydraulic fracturing. Water is an indispensible part of the process, because without it there would be no way to produce the slurry that keeps fractures open to allow the release of shale gas so it can flow freely to the pump at the Earth’s surface.

From the sand mines to the well to the pipeline, water is the thread that connects it all, and CST is helping ensure water is used and recycled in a way that’s responsible and cost effective.

The Process

Sand for fracking is produced in the following steps:

1. Sand is mined.
2. Water is mixed with sand.
3. Sand is classified by coarseness, fineness and other qualities.
4. Silt and clay are removed, forming a slurry.
5. Slurry is moved to a clarifier tank, where solids are separated and removed.
6. Reclaimed water flows to the process water tank.
7. Water is reused for washing and classification of more sand.

CST supplies TecTank bolted steel liquid storage tanks for the water clarifying and storage (steps 5, 6 and 7). Its clients include companies like Process Engineers and Equipment Corporation, which manufacture the systems for sand wash plants that separate the clay and silts from sand and recycle the water.

“One of the objectives is to get the job done with minimal water use,” says Rick Howie of Process Engineers and Equipment Corporation. “We think of sand processing as an important part of an environmental assistance program.”

Waste treatment of the slurry requires two tanks: a clarifier tank and a water tank. Clay, silts and water are fed into the clarifier tank, where flocculant chemicals are introduced to settle solids at the base of the tank. A rake assembly collects the slurry, which is pumped out. The clean water is collected at the top of the tank through the launder and is discharged into the water tank, where it’s pumped away to be reused for washing and classification of more sands.

The Challenge

As petroleum manufacturers identify new deposits of shale gas, frac sand is increasingly being sourced closer to the shale to improve efficiency and lower costs. That means providers of sand processing and recovery systems must be extremely nimble and ready to design, build and launch on demand.

Fracking operations have traditionally used Northern White sand, which is mined in mid-western states (Illinois, Indiana, Iowa, Kansas, Kentucky, Minnesota, Michigan, Missouri, Nebraska and Wisconsin). Northern White is considered superior for fracking because of its uniform size, high quartz content and purity and is shipped by rail to fracking sites across the country. However, shale gas plays in Texas have grown at such a rate that it’s no longer cost effective to ship sand from the Upper Midwest. Operators have turned to Texas Brown sand with greater frequency. In fact, Rystad Energy predicts the share of Northern White used in fracking will drop from 75% in 2014 to an expected 34% in 2020.[1]

“Most of these sand classification plants operate for about 20 years,” says Howie. “They have to remain active during the entire life of the sand mine. As more types of regional sand is cleared for use you’re seeing plants spring up in many new areas so it can be locally sourced, near the gas well.”

Add to this the fact that demand for frac sand is dynamic. The amount of sand used in each well has increased 15% over the last 2-3 years.

“Because the delivery expectations of this market are high, we are prepared to work with customers to provide tanks faster,” says Matt Bedell, Senior Project Manager at CST Industries. “The key to success is agreeing to expectations as soon as possible so we can disseminate the information through our shop.”

Bedell says compressed timeframes are part of the game, and sometimes the information doesn’t flow to the factory until all decisions are made, which can eat into CST’s project timelines. 

“We will be transparent with our schedules so our manufacturing timelines are appropriately integrated with the customer’s project schedule,” says Bedell. “But it’s not always perfect, so in those instances, we work with our internal departments to find ways to support our customer.”

The Application

A typical clarifier tank is 100 feet in diameter by 22 feet tall, with a capacity of well over one million gallons. Clarifier tanks are equipped with an effluent launder with adjustable V-notch weir. The water tank is 70 feet in diameter and 20 feet tall, with a capacity of over 500,000 gallons. Standard sizes are available but CST also works with customers to fabricate tanks to specific dimensions to meet their flow rates.

“CST understands the water treatment process and they know our requirements, which means their tanks are extremely adaptable and durable,” says Howie. “We ask a lot of these tanks because an ideal operation will process 18,000 gallons a minute for 20 hours a day nonstop. These systems recycle over 90% of the water for future use.”

CST’s TecTank storage systems are coated in TricoBond epoxy coating using the OptiBond coating process which delivers outstanding performance and is the industry standard for epoxy durability. They have been used in more than 350,000 field-tested applications in more than 125 countries throughout the world.

“Coatings are the first line of defense in protecting the integrity of your assets,” says Bedell. “No other manufacturer comes close to our level of knowledge of how to apply epoxy coatings and how they endure in some of the harshest environments.” 

Bedell continues, “The customer provides us with its requirements and objectives and we will design a tank to meet their needs. We go through an approval process to ensure our scope of work is understood and agreed by everyone and then move into fabrication at our Parsons, KS plant. Because timelines are sometimes tight, we will work with customers to deliver the tanks faster.”

For sand wash plants, CST tanks are assembled from the ground up and sit on a base ring embedded in concrete.  

“Most of the end users who buy these systems are also providing the sand used during the hydraulic fracturing process. Our customers need large amounts of water to be recycled to run a safe, clean and efficient facility,” says Bedell. “However, we do provide shop welded clarifiers to customers who only need to process a small amount of water.”

By all accounts, the demands of the fracking industry will continue to grow, as it is a proven cost-effective way to extract once-inaccessible oil and natural gas deposits. In fact, up to 95 percent of new wells drilled today are hydraulically fractured, accounting for two-thirds of total US natural gas production and about half of US crude oil production.

Howie says the amount of sand used in each well has increased 15% over the last few years, which will create additional demand for his company’s systems.

[1] Key Highlights and Analysis from the 4^th Annual Frac Sand Industry Update Conference, PLG Consulting, February 13, 2019, https://plgconsulting.com/featured-insights/frac-sand-update-2019/

The post Where the Frac Sand Goes, CST Follows appeared first on CST Industries.