Seaworthiness, also known as Fitness For Service (FFS), assessment of marine structures and machinery components is performed in accordance with the actual ship classification society’s Rules and/or Standards. The maritime industry is for the time being taking an interest into Additive Manufacturing (AM) for the sake of design and manufacturing cost optimization. Components of particular interest appear to be valves, heat exchangers and propellers. For conventional manufactured materials, for example cast, forged, rolled, and extruded copper alloys there are well established marine classification rules and standards. Recently, Ship Classification Rules and Standards for AM materials has been published. The seaworthiness or FFS of a Ni Al bronze (NAB) marine propeller constructed by Wire Arc Additive Manufacturing (WAAM) has been scrutinized by a novel approach of combining conventional material qualification procedures with identification and data acquisition (DAQ) of essential WAAM process parameters. A 520 kg heavy marine propeller, with a diameter of 2 m, was manufactured by the South Korean company SY Metal under strict observation of DNV South Korea. In this report the authors are presenting essential WAAM process parameters and authentic mechanical properties of the Ni Al bronze WAAM marine propeller; benchmarked toward authentic NAB cast propeller data. © 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0)

For additive manufacturing (AM) products such as structural and machinery components, the quality should be verified. In maritime industry, this task is performed by classification societies who are acting as independent third party and certifying such components. In the case of, eg, cast-steel products, standards are available, which specify sampling procedures, properties, and destructive and nondestructive test methods as well as relevant material requirements for design purposes. For AM products, currently only few supportive standards are available. In tough market situation products must be cost-efficient. Therefore, mandatory verification of products can only be enforced for vital applications. Unified, meaningful sampling and testing scopes are needed for application at different manufacturing locations and for evaluation by “no AM expert” staff. The impact of manufacturing defects in the AM process on the integrity on the AM product has to be evaluated. Contract partners may, or have to ask for evidence for the integritiy of AM products by certificates issued by third-party institutions. DNV GL as a classification society has set up procedures for initial qualification and certification of AM products. This paper focusses on inspection and certification of AM maritime products and fit-for-purpose assessment.