He notes that the industry seems to have reached a challenging point between roughly 5,000 and 6,500 feet deep where the contradictory metrics of pressure resistance, combined with an operational need for larger diameter pipe, requires more steel. But more steel means more weight, which increases the axial force near the riser hang-off, which in turn requires more steel, Burke explains.
“Composite pipe resolves this technical tension by adding the optimal pressure resistance needed, without the associated weight penalty that traditional designs would incorporate,” he says. GE’s solution leaves the dynamic and highly-loaded components of flexible pipe unchanged. “Specifically, the tensile armor layers and the end fittings remain unchanged, allowing operators to retain and leverage their existing knowledge and understanding of these products,” Burke says.
FiberSystems supplies its corrosion-resistant methacrylate epoxy FRP pipe to chemical manufacturers that need a high-performance alternative to alloys and specialty metals for projects with fire-retardant and explosion-resistant requirements. Photo Credit: FiberSystems
As he puts it, the challenge – and solution – is in making lighter, cheaper products that can reach deeper and safer than ever. And it is a significant challenge, given the tough environment. “Bear in mind just how critical the durability and robustness of these products is,” Burke says. “They will be installed into thousands of meters of turbulent seawater; attached to a highly dynamic platform; exposed to high pressures, wide temperature ranges, fluid surges, shut-downs and chemically aggressive well contents – and they are expected to function continuously, without intervention or maintenance for 20 or more years.” This means there is a very high qualification threshold, and a range of life-cycle and environmental testing must be completed and independently verified before a product can be operated subsea.
It was a challenge that FiberSystems had to address when tasked with modifying a positive break tank on a potable water system aboard the world’s deepest offshore oil drilling and production platform. Shell Exploration & Production contracted Jacobs Engineering to oversee the modifications for the offshore platform in the Gulf of Mexico. The tank needed to let out gases trapped in the service line and let in seawater that would pass through the water makers that would turn it into drinking water. The tank needed to be corrosion-resistant, lightweight and low maintenance, which is what led the engineer to FRP.
“One of the problems we had to solve was how to anchor a freestanding pipe on the inside of the tank,” says Dave Orr, production supervisor for FiberSystems, the tank manufacturer. “Fabricating the tank’s cradle and determining the best method for adhering the top dome to the main body of the tank was also challenging.”
The main body of the tank, along with eight stubs and flanges, was filament wound using a high-performance grade of methacrylate epoxy resin pigmented gray. To meet a tight turnaround time, the fabricator used 113 yield fiberglass that allowed it to build tank walls up quickly – twice as fast as the thickest glass. The tank’s flat base and cradle also were filament wound. A hand lay-up process was used to fabricate the tank’s upper and lower domes, which were then bonded to the tank with adhesive.
Strength was paramount for this application. The joints were butt-welded and wrapped for added strength, and the fabricator used a resin wax coating to seal interior layups, the freestanding pipe inside the tank and the exposed openings. The final product weighed 1,000 pounds and measured 11 feet, 8 inches tall with a 30-inch inside diameter.
Challenge #4: Conservative companies are slow to adopt new solutions.
Opportunity: Existing FRP solutions are poised to meet new demands.
Burke notes that customers appreciate seeing products that meet their needs for lightweighting and corrosion resistance without the associated risk of brand-new technology. Even so, fabricators are constantly watching for the next innovation. He cites several improvements in materials, including these:
- More robust polymers that can operate at higher temperatures and pressures
- Stronger fibers to withstand harsh environments
- Structural geometries and manufacturing methods to incorporate fibers and polymers in “unique and advantageous means,” such as pultrusion technologies
- Incorporation of additional functionality into the pipe structure, such as fiber monitoring for operational monitoring
“These are all of great interest to us as we contemplate the next generation of composite pipe for offshore oil and gas production,” Burke says.
Busel predicts that to better meet future demands in the chemicals and other processing industries, FRP fabricators will need to experiment with resins that can withstand higher temperatures.
In certain industries, a little experimentation can be a big risk, points out Dan Naugle, general manager for Composites USA in North East, Md. “Big companies like Honeywell, DuPont, Dow Chemical, etc., are pretty conservative in that they approve certain resins, in certain products, with certain processes. If it works for them, they don’t want to change it because they are getting into an unknown,” Naugle says.
In some cases, today’s needs can be met by taking a fresh look at how tried-and-true products can meet new applications. For example, Aram Mekjian, president of resin distributor Mektech Composites Inc. in Hillsdale, N.J., says that phenolic resins should be more closely considered in certain corrosive environments due to their heat-resistant properties.
“Phenolic resin is a little more difficult to use – it requires heat to cure – but the big advantage over any of the other resins is the far superior fire, smoke and smoke toxicity properties,” Mekjian says. “Also, it has very good high-temperature resistance.” He adds that phenolic ducting passes Factory Mutual (FM) requirements. “Other polymers would require water sprinklers inside the duct to reduce flame spread and heat release, which would cause failure,” he says.
Busel agrees that phenolic resins are a strong alternative for high-temperature applications. But, he adds, it all comes down to the application. “The debate goes on out there that fire-retardant resins are just as good as phenolics. Each has its own strengths,” he says.
“We use phenolic resins, which are very good for sulfuric and hot hydrochloric acid – very good for hot acids,” Istre says. “But they’re not very good for caustics, so we have to watch the application.”
And while the material does need to be processed differently than vinyl esters, Mekjian points out that even in the composites industry some misconceptions around phenolic processing may remain. “Some fabricators may still not know that phenolics can be processed via hand lay-up and filament winding,” he says. “Most still think phenolics are used in the form of prepreg used in autoclave.”
Challenge #5: FRP is still an unknown for some markets.
Opportunity: Targeted education can lead to a new generation of end users.
For many conservative end users FRP is still a relatively new solution, at least compared to materials such as steel. As a result, customer education remains a critical business development tool.
“A lot of companies aren’t aware of what FRP can do,” says Naugle. “There are some companies that have always used steel tanks or piping that have come to us and said, ‘Show us the advantages.’” Naugle is quick to point out benefits, including FRP’s ability to create custom shapes. For example, during building rehabilitations new pipes often have to go around existing pipes and other structures. “You can’t do that with steel duct; It just can’t be formed that way,” Naugle tells customers. “But with FRP, you can make custom pieces to fit in those areas.”
Trenary points out today’s up-and-coming engineers are entering the market with a greater understanding of composites and, as a result, greater willingness to evaluate the material’s merits for specific projects and products. They don’t simply default to metal or concrete with a cursory consideration of composites. “This shift, although a longer term development, will likely result in significant further acceptance and standardization in the FRP composite corrosion market,” he says.
Trenary finds the biggest challenge to growth for the corrosion-resistant FRP industry is its fragmentation. “While FRP has been successfully used in a wide range of markets for many decades, there still tends to be some significant differences among suppliers with regard to design practices and design capabilities,” he says. “In addition, it is often difficult for a customer or end user to identify a single published specification that they can rely upon for standardization.” For example, ASME RTP-1 is an FRP tank standard, but not all design variables allow use of the standard, says Trenary.
Morton adds that in some instances, end users view FRP as an exotic choice that will solve any problem, and that’s a challenge that demands more education as well. When FRP is misapplied, its failure can present problems for the industry.
“I had a customer call and ask for some piping that would haul sulfuric acid,” says Morton. “Unfortunately, FRP pipe is not the right material to use, although you can use an FRP tank to store sulfuric acid if it’s stored below ground because the ground acts like an insulator. So we find that there are still questions, and education needs to be given out there.” As Morton puts it, “Is FRP right for every job? No. But it’s right for a lot of them.”
And the possibilities are increasing. Now it’s up to FRP suppliers to educate end users on how composite pipes and tanks can be the best choice for them.
