[Composite Materials 101] SB, Secondary Barrier for Safe LNG Transport
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<p>To transport Liquefied Natural Gas (LNG) safely, advanced and highly reliable technologies are essential. LNG must be maintained at an ultra-low temperature of –163°C, and safely contained even under the vibrations and motion of a moving ship. This demands not only exceptional insulation but also a fail-safe mechanism—namely, a “secondary barrier” system to protect against potential leakage.</p>
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Hankuk Carbon has recently expanded its production lines for LNG insulation materials, including the Secondary Barrier (SB), further reinforcing its supply stability and technological leadership in the insulation materials market. But why is the SB so critical in the LNG industry? And what is the significance of expanding our production capabilities?</p>
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In this episode, we will delve into the role of SB technology within the insulation systems of LNG carriers, the engineering behind it, and how Hankuk Carbon’s proprietary capabilities are creating a competitive edge in the global market.</p>
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<span style="font-size:20px;"><strong>The Engineering and Necessity of the Secondary Barrier (SB)</strong></span></p>
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<p>The Secondary Barrier (SB), also known as “Triplex,” is a high-performance composite material used in the Mark III insulation system developed by the French company GTT (Gaztransport & Technigaz). Mark III is a globally adopted insulation system for storing and transporting LNG. Major shipbuilders including Hyundai Heavy Industries and Samsung Heavy Industries base their LNG carrier designs on this system.</p>
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<p>The Mark III system is composed of the following layers:<br />
<strong>- Primary Barrier:</strong> A stainless-steel membrane that directly contacts the LNG. It acts as the first line of defense, preventing the cryogenic liquid from leaking.<br />
<strong>- Insulation Layer (R-PUF): </strong>Surrounding the primary barrier, this high-performance rigid polyurethane foam (R-PUF) maintains cryogenic temperatures and absorbs external shocks.<br />
<strong>- Secondary Barrier (SB): </strong>A composite layer made of aluminum foil and glass fiber. It acts as a fail-safe containment system, preventing LNG from reaching the ship’s hull in the event of primary barrier failure.</p>
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<p>SB is categorized into two types: the flexible type (FSB) and the rigid type (RSB), each strategically placed depending on the cargo tank’s structure. These materials must meet strict standards for mechanical strength, flexibility, impact resistance, and cryogenic stability—ensuring reliable performance in extreme environments.</p>
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<p><span style="font-size:20px;"><strong>Hankuk Carbon’s Competitive Edge in LNG: Technology & Capacity</strong></span></p>
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<p>SB is a highly specialized composite material that must meet rigorous international standards and certifications. Due to the high technical barriers, only a few companies worldwide are qualified to supply it. Hankuk Carbon is the exclusive domestic manufacturer of SBs for the Mark III Flex system, achieving localization through proprietary technology and securing a strong competitive position.</p>
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In 2017, Hankuk Carbon successfully developed a high-strength FSB incorporating aramid fiber, receiving formal certification from GTT. With deep expertise in material design, precision processing, and global compliance, Hankuk Carbon has established itself as a trusted supplier in the global LNG insulation materials market.</p>
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In March 2025, Hankuk Carbon initiated a new round of investments to expand its LNG insulation material production lines. As a result, its SB manufacturing capacity—previously sufficient for about 70 vessels—will significantly increase. Furthermore, a new foaming line for R-PUF has been introduced, replacing aging facilities to improve productivity and reduce defect rates. This marks a critical milestone in strengthening Hankuk Carbon’s long-term supply capabilities.</p>
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In 2024, Hankuk Carbon’s SB was officially recognized as a “World-Class Product” by the Ministry of Trade, Industry and Energy of Korea. Previously, in 2022, it was also awarded Green Technology Certification by the Ministry of Oceans and Fisheries. These milestones confirm Hankuk Carbon’s global competitiveness and reliability, achieved through localized innovation.</p>
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<p>As LNG continues to serve as a transitional energy source in the shift toward a cleaner future, demand for LNG carriers is expected to remain strong and steady. At the core of this growth lies a technology that works behind the scenes—SB—and the company that brings this technology to life: Hankuk Carbon.</p>
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<p>With the recent expansion of our production lines, Hankuk Carbon is poised to grow as a trusted partner in the LNG industry, backed by robust, reliable, and future-ready composite technologies. See you in the next story with more valuable insights about composite materials!</p>
- Composites
- FSB
- RSB
- Ship
- LNG Carrier
- Expansion
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