Technology overview: In liquefied national gas (LNG) carriers, cargo containment systems (CCS) that store LNG, are a decisive factor for deciding the performance of vessels in terms of the characteristics of the structure. Polyurethane insulation panel is used as a material of the CCS’s structure  to secure the safety of LNG carriers at ultra-low temperature (-170℃). The main adhesives for LNG carriers are used to avoid matters regarding leakage by firmly bonding such structure. Most of all, adhesives for the secondary barrier are most crucial to the safety of LNG cargo containment system, so advanced technique is required to meet the standards for material properties required by the international certification agencies and shipbuilding  companies. To overcome the weakness of epoxy adhesive as the traditional adhesive for secondary barrier in terms of pressure decay at the ultra-low temperature, urethane adhesive by foreign makers was replaced. However, when drying at high temperature and humidity, urethane adhesive responded with negative reactivity against moisture and created foam, thus leading to a problem with leakage, which is the fundamental problem that urethane response mechanism had. New curing reaction mechanism was employed to resolve the problem with foam arising from negative reactivity. Additionally, stable bonding material system was successfully developed to meet the requirements for the international certification agencies and the shipbuilding companies.

Industrialization: As the adhesive system for LNG secondary barriers changed from the conventional epoxy system to urethane, only one foreign maker produced the products that met the requirements for material properties around the world, so the maker became the exclusive supplier. Under the circumstances, NOROO Holdings  Co., Ltd. reduced dependence  on the foreign maker for core materials, obtained the differential technology of LNG ship construction, the world’s first, by developing domestic technology with the reflection of improvements in foreign products by shipbuilding yards to play a leading role in obtaining the international technological competitiveness for the industrialization of products. This urethane bonding system is used for automatic, manual, and Pump Tower Base Support (PTBS) and the sets of the secondary barrier bonding system have been domestically produced for the first time in Korea. After finishing the application test for shipbuilding companies, NOROO is expanding the share in the domestic market. The company gained recognition for its technology from foreign shipbuilding yards and received orders, so it is expected to increasingly improve exports. In addition, it will play a prominent role in shipbuilding technology and the market competitiveness in Korea by developing the substitution of other Top Bridge  Pad (TBP) adhesive, which is used for LNG containment system, and MASTIC adhesive with urethane system.

Problem-solving in industrialization: In designing urethane composite resin of LNG cargo containment systems required at ultra-low temperature, the optimal curing response was obtained by meeting the various requirements, such as working safety while drying at high temperature and humanity, foam control, material impregnation and adhesiveness, and manual labor. However, after a series of trials and errors, the company was able to overcome such barriers by establishing the suitable new curing system design. It obtained Mock-up assessment and Yard verification by systematically cooperating with shipbuilding companies, which are the clients, secured material properties by doing the long-term reliability evaluation from outsider institutions, and received the approval from the Gaztransport & Technigaz (GTT), an international certification company. It succeeded in obtaining quality certification and accomplishing mass-production by receiving four certificates of ship classification.

Technology developer: NOROO Holdings  Co., Ltd. / +82-31-467-6092/ www.norooholdings.co.kr

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