From international standards to classification rules: application on board ships of adhesive non-structural fasteners

Large ships’ outfitting stage is a complex process that requires careful attention to safety and timelines. This simultaneous activity of different personnel introduces a high degree of risk regarding their safety and security. Excellent coordination among many individuals and installation teams is required. One of the primary risk factors onboard during the outfitting phase is fire. Over the years, various precautions have been implemented to mitigate this risk, from preassembling external components to strict control over processes requiring welding or other types of hot workings. An alternative to these processes could be the use of semi-structural adhesives. Currently, bonded components are limited to a few secondary elements, typically small in size and non-critical to the ship’s safety. The economic incentive for semi-structural bonding on cruise ships is substantial, with increased production capacity associated with many components eligible for semi-structural bonding. One of the limits of using adhesives on board steel ships is the need for specific normative, which poses an obstacle when introducing new solutions. Classification societies require an in-depth study demonstrating adequacy and safety and removing doubts regarding adhesive solutions’ long-term durability. Until 2019, adhesives were approved for specific case-by-case for specific nonstructural bonding uses. There were no approvals for semi-structural bonding processes. Within this context, the Glu&Nav project was funded some years ago to examine and outline a standardized application process for semi-structural bonded fasteners. The research was carried out through a collaboration between the shipbuilding industry, university, and classification societies. The result was the definition of a pre-certification process by a leader classification society, which eventually came into force on January 1, 2021. This paper presents the transition process from the existing regulatory framework to the ratified standard for non-structural bonding, providing detailed insights.