HD Hyundai’s safety solution for ammonia-fueled ships gets KR’s stamp of approval

September 16, 2025, by Aida Čučuk

Classification society Korean Register (KR) has granted approval in principle (AIP) for Hi-CLEARS, a safety solution for ammonia-fueled ships, developed by the affiliates of South Korean conglomerate HD Hyundai – HD Hyundai Heavy Industries (HD HHI) and HD Korea Shipbuilding & Offshore Engineering (HD KSOE).

As disclosed, Hi-CLEARS is a safety-enhancing system set to capture ammonia gas leaked during operation, converting it into aqueous ammonia, and using it as a reductant in a selective catalytic reduction (SCR) system. The solution reportedly eliminates potential ammonia leakage and achieves “zero discharge” of ammonia to the atmosphere and sea.

It is understood that KR participated in amending IACS Unified Requirement M77, which governs the application of SCR systems on ships. The revision allows the use of aqueous ammonia and gaseous ammonia as reductants, whereas their use was previously restricted. According to KR, the change provides the technical foundation needed for the commercialization of Hi-CLEARS.

Yoo Byungyong, Senior Vice President of HD KSOE, commented: “Hi-CLEARS safely processes ammonia leaks and treats the resulting liquid through SCR, thereby meeting both safety and environmental regulations. Through close cooperation with KR, we have enhanced its commercial viability while also strengthening our global competitiveness.”

Ryu Hongryeul, Executive Vice President & CTO of HD HHI, said: “This joint development marks an important achievement in addressing two key challenges of ammonia-fueled vessels?reducing ammonia discharge and utilizing it for harmful gas treatment. Leveraging the strong partnership between shipyards and KR, we will further reinforce our leadership in advancing next-generation eco-friendly technologies.”

Lee Yongsok, Executive Vice President of KR, stated: “This AIP goes beyond technical validation to advancing international standards. By contributing to revisions such as IACS Unified Requirement M77, KR is helping to create the regulatory foundations that make ammonia-fueled ships a safe and viable reality. We remain committed to refining technical rules and requirements in line with technological progress and evolving industry needs, and to leading the decarbonization transition as a trusted partner to the global maritime community.”

In other news, KR approved HD Hyundai Mipo and HD KSOE’s IMO Type-C tank as part of efforts to meet the growing demand for eco-friendly fuels such as LNG, ammonia, and hydrogen.

As part of the project, HD Hyundai Mipo evaluated the structural and fatigue strength of the tank, while HD KSOE led the tank design and structural integrity assessment. KR conducted a comprehensive review of the design in accordance with its classification rules and international regulations, which enabled the issuance of the approval.