The Toughness of Tanks
Geoff Clarkson, P.Eng., doesn’t fabricate composite storage tanks, but he knows a lot about what makes them last – and fail. Clarkson founded UTComp in 2008 to offer engineering and inspection services to the composites industry. Using the company’s UltraAnalytix™ non-destructive inspection system, he has assessed dozens of FRP tanks through the years. The outlook for most of these composite assets, he says, is extremely positive. “Composite materials seem to significantly outlast predictions by the designers, manufacturers and constituent material suppliers,” says Clarkson. “That’s a really good result.” Consider the oldest tank that UTComp has inspected – a 62-year-old tank that stores a sulfuric acid solution in a metal processing plant in Quebec, Canada. The plant owner knew the tank wasn’t leaking, but was unsure if any other deterioration had occurred. So he called in UTComp for an ultrasound analysis, which revealed the tank “is still doing extremely well in a very corrosive environment,” says Clarkson. The composites industry has changed dramatically since that tank was built and installed in the late 1950s. There have been tremendous advancements in materials and technology, in addition to rising customer expectations and the adoption of numerous standards and regulations surrounding the use of FRP in storage tanks. But the longevity of composites remains one of its strongest selling points. “FRP is designed to stay in its original watertight, functional design from the day the tanks are delivered until the end of their service life, which in most cases is the life of the building or installation,” says Bruce Coe, regional sales manager for water applications in Canada and the U.S. for ZCL | Xerxes, a product line of storage tanks within the Composite Product Systems division of Shawcor Ltd. “That’s the value proposition of FRP products. It’s not the cost today: It’s the value proposition of a composite-built tank over the next 30 to 50 years.” Factors that Influence Material Choice While the long life of composites is appealing, it’s not the only decision-making factor that end users consider today when selecting tank materials. “The structure, the use and the budget dictate what the customer chooses,” says Coe. In the water and wastewater market he serves, most tanks are built from concrete, GFRP and high density polyethylene. HDPE is cheaper than GFRP, but doesn’t last as long. “The above-ground tank market changed 20 years ago with the advancement of HDPE technology,” says Coe. “As the material became better and stronger, a segment of the market made an economic decision to buy a cheaper product that may need to be replaced in 10 or 12 years instead of a fiberglass tank.” For applications where the tank is small and easily accessible, some customers are willing to foot the replacement costs because an HDPE tank may be one-quarter to one-third the cost of a GFRP tank. However, HDPE probably won’t meet the structural requirements for tanks with about a 15,000-gallon capacity or above, says Coe. He recently got a call from a potential customer in need of six 50,000-gallon underground tanks. “That eliminates HDPE and makes FRP competitive with concrete,” he says. “It’s right in our wheelhouse to deliver that much storage to a site that’s watertight and will last a lifetime.” Another option in the tank industry is dual laminate FRP composites, which combine a thermoplastic inner liner with a GFRP exterior. Dual laminates grew in popularity as customers required tanks that could store high-temperature gases or liquids that were more caustic or under higher pressures. “Thermoplastic liners typically have the ability to contain all that, but don’t have the structure to support it like a fiberglass piece of equipment can,” says Tim Schoessel, president and owner of Tri-Clor Inc., a fabricator in Hastings, Mich. “In dual laminates, the two materials are married and work well together.” In corrosive environments, such as the chemical processing industry, they compete well against metals like high nickel alloys and titanium. Advancements in Material Technology Increasing end user demands drive innovation in composites. “Our customers in the chemical world are trying to stretch the limits of their equipment,” says Schoessel. “If they push the boundaries, then we follow closely behind and develop the equipment they require.” Suppliers aid the cause with new resin and fiber technology. “Materials have advanced,” says Joe Puthoff, president of Plas-Tanks Industries Inc., an FRP vessel manufacturer in Hamilton, Ohio. “We’re still using resin and glass to build the tanks, but new technologies allow us to offer better corrosion resistance [to customers] and improve efficiencies in our facility.” The latter – improved efficiencies – is critical to fabricators seeking a competitive edge. INEOS Composites in Dublin, Ohio, is one of several resin suppliers introducing new, more efficient products to the market. In 2018, INEOS rolled out its Derakane™ Signia™ line of epoxy vinyl ester resins, which are formulated to offer faster laminate consolidation, lower foaming and reduced sanding for application of secondary laminations, according to Kevin Lambrych, manager of the INEOS Corrosion Science Center. The Derakane Signia resins also provide improved cure kinetics. “That allows fabricators to process thicker parts,” says Lambrych. “The parts cure without excessive heat, so they don’t warp, twist or burn.” In addition, the new resins contain a novel vapor suppressant technology that forms an air activated film, thereby reducing styrene emissions during curing. “That’s beneficial to us in the plant and from an environmental standpoint,” says Puthoff. Advancements in resins from INEOS and other leading material suppliers build upon tried-and-true technology that make composites an attractive option for tanks in a variety of industries, from chemical processing and mining to wastewater treatment and pulp and paper. Composites are corrosion resistant, strong, lightweight and flexible – all of the attributes required by a nuclear power plant in the northeast that reached out to Plas-Tanks for three storage tanks. The nuclear power plant needed three 10,000-gallon tanks to store chemicals in its current facility. “Part of the scope requirement for us was to build tanks that could be easily installed within this existing structure,” says Puthoff. Plas-Tanks fabricated each of the cylindrical tanks in four separate pieces – the bottom, two middle sections and the top. In early 2020, the pieces will be shipped to the nuclear power plant, where Plas-Tanks’ employees will laminate the pieces together on-site. “There’s a lot more flexibility and options with FRP than other materials,” says Puthoff. “If you get in the field and realize there’s a problem with the structure, it’s very easy to modify on-site. You can cut another hole or put a fitting in another spot. Alloys can be welded in the field, but composites don’t require traditional welding, so there’s no worry about open flames or permits to weld.” Regulations that Impact the Market Perhaps one of the biggest influences on the tank market is regulations. “Regulations are becoming stronger across all of our platforms. They are the driving force for all FRP products,” says Coe. “We’re not promoting these regulations, but we’re also not pushing against them. We are simply meeting our customers’ requirements.” ZCL | Xerxes sells underground tanks to a variety of industries, including petroleum. In July 2015, the Environmental Protection Agency (EPA) revised its underground storage tank regulation originally adopted in 1988 (Code of Federal Regulations, 40 CFR Part 280). The goal of the regulation is to prevent underground storage tanks from leaking and contaminating the groundwater. Among the requirements, tanks must provide cathodic protection and be double-walled so they can be monitored. While the EPA regulation addresses the more than 550,000 underground tanks nationwide that store petroleum and other hazardous substances, there are a plethora of other regulations – mostly state and local – that provide what Coe calls “built-in growth opportunities” for tank suppliers. And they extend beyond tanks for caustic gases and liquids. “Today, those regulations happen in the water industry as well,” says Coe. “Jurisdictions across the country are requiring new construction to incorporate water reuse.” For instance, properties over a certain size in California will have to collect the water used in sinks, showers and toilets in the building, clean it on-site and reuse it to flush toilets or irrigate the land once SB 966 is implemented. (The bill was signed into law by Governor Brown in September 2018.) A social media company in northern California ordered five underground tanks from ZCL | Xerxes to accommodate its on-site wastewater treatment system at two new buildings. The goal was to treat between 40,000 and 50,000 gallons of waste a day, which would then be used for all the company’s non-potable demands, including toilet flushing – the largest consumption of water in any business office. “Technology firms are very progressive in their management of water, and the composites industry benefits from that because they want something that will last the life of the building,” says Coe. ZCL | Xerxes has moved into another area where regulations are beginning to play a large role – the storm water business. “Storm water is what hits the pavement, and rainwater is what hits the roof,” says Coe. “The difference between the two is one has hydrocarbons and one does not.” Storm water runoff can include oil, grease, pesticides, nitrogen and other contaminants. Local governments are starting to enact regulations to mandate the retrieval of storm water before the polluted water hits a stream, river, lake or other water source. Most of the focus on storm water is in regions along water, such as the Atlantic and Pacific coastlines. “The old adage is all politics are local,” says Coe. “In water, all regulations are local.” The Clean Water Act, enacted in 1972, is the primary federal law governing water pollution. However, it has never been fully enforced and continues to be a source of political friction. The U.S. Supreme Court heard arguments in November in a case (No. 18-260, County of Maui, Hawaii v. Hawaii Wildlife Fund) that could settle a portion of national water regulations – and greatly impact the tank industry. The Importance of Solid Design One unintended consequence of regulations is the tendency of designers and engineers to become conservative and over-design tanks. Lambrych encourages industry professionals to be champions of FRP and appropriate design. He cites temperature requirements as one example: “Oftentimes there is a maximum operating temperature [for tanks] and a design temperature,” he says. “There’s a struggle when engineers put a safety factor on top of a safety factor. The next thing you know, you have a design temperature that doesn’t make much sense for the FRP or the process [the customer] is running.” Over-design also occurs when customers aren’t knowledgeable about composites. Plas-Tanks recently fabricated three tanks, 13 feet in diameter and 31 feet long, for a chemical manufacturing plant in the Middle East to store hydrochloric acid. In addition to the tanks, the company produced GFRP saddles to support the horizontal tanks. “Our saddles are typically hollow inside, but the end user was hesitant to use hollow saddles,” says Puthoff. “They didn’t think it would be supportive enough, so we are filling the saddles with resin to provide additional strength properties. It isn’t required for support, but it will give the end user ease of mind.” In Clarkson’s experience, when tanks fail it’s often not the fault of the material or construction. “A lot of problems that people have with FRP are related to how the tank was installed in the facility and what happened to it – things like process upsets, where there was a temperature excursion or a pressure spike,” he says. Working hand-in-hand with designers and engineers during the design process can help combat process upsets and other on-site failures, in addition to curtailing over-design. “It’s worthwhile for manufacturers to really quiz end users on their process controls,” says Clarkson. For example, if fabricators ask customers to fully explain where and how the tanks will be used, then they may be able to offer design advice to head off potential problems with temperature deviations, pressure spikes and other issues. “A number of failures or near failures we’ve observed have occurred because somebody took a short cut at the design stage,” says Clarkson. “It’s in the best interest of the buyer to have somebody go through the details and look at how the equipment is put together, installed and used.” A well-designed, well-made FRP tank can be virtually maintenance-free and last for decades. “Composite tanks are lasting a long time – and can last even longer,” says Clarkson. “But we have a significant need globally to give good advice on fitness for service and the ability of a storage tank to stay in service.” Collaboration Is Key to Market Growth The best way to advance the use of composites in the tank market is for industry experts to work together with their peers, as well as engineers, designers, consultants and others in the market. Both Schoessel and Puthoff are part of a group that meets twice a year to discuss the American Society of Mechanical Engineering’s RTP-1 standard for reinforced thermoset plastic vessels. The group has open discussions about end user needs where members share ideas. It also has a sub-committee dedicated to marketing, which is planning a conference to educate engineers about FRP tanks. “Working with engineering firms is important because ultimately they are the ones writing the specifications we have to adhere to,” says Puthoff. “We need to educate them on composites versus alloys and other materials.” INEOS strives to educate engineers, as well as industry partners, through its Corrosion Science Center (CSC). The goal of the CSC is to grow the usability and profitability of FRP composites in corrosion-resistant applications. It has held lunch-and-learns with engineering firms like FLSmidth & Co. to share advice on topics such as maintaining FRP equipment and identifying a third-party inspector. Ultimately, sharing ideas and knowledge rather than working in individual silos remaining tight-lipped about your expertise will benefit the entire composites industry. Says Puthoff, “There’s a much larger market share out there that could keep all of us busy if we work together.”
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