Classification society and class-approved material
Independent bodies that inspect the design, construction and maintenance of ships and offshore structures against their rules and assign “class”; IACS members include DNV, ABS, Lloyd’s Register, Bureau Veritas, ClassNK, RINA, KR, CCS and Türk Loydu. Most shipyard materials – plate, sections, pipe, welding consumables, coatings, rope, chain and pumps – must come from class-approved makers, with tests witnessed by the class surveyor and a class-stamped certificate, often EN 10204 3.2. Unapproved material puts the vessel’s class at risk.
Related terms
EN 10204 mill test certificate (2.2, 3.1, 3.2)
The European standard defining types of inspection documents for metallic products – plate, pipe, sections, castings and forgings – used worldwide under the name “mill test certificate” (MTC). Type 2.2 gives the manufacturer’s non-specific test results; Type 3.1 gives chemical and mechanical results specific to the delivered lot, validated by the manufacturer’s independent inspection representative; Type 3.2 additionally includes tests witnessed by the purchaser or an independent body such as a classification society. Pressure vessels, shipbuilding and energy projects usually require 3.1 or 3.2.
Steel grade designation (EN, ASTM, AISI, JIS, GB)
Steels carry different names in different standard systems. In the European system (EN 10027) a letter shows the use and a number the minimum yield strength: S235JR is a structural steel with 235 MPa and impact tested at 20 °C, while S355J2 is tested at –20 °C. Approximate equivalents are ASTM A36 or A572 Gr.50, JIS SS400 in Japan and GB Q235/Q355 in China; for stainless, AISI 304 ≈ EN 1.4301. Equivalents are not identical, so chemistry and mechanical values should be checked on the certificate.
Antifouling coatings and the AFS Convention (TBT ban)
Coatings that stop algae, barnacles and other organisms attaching to a ship’s hull; fouling increases drag and can raise fuel consumption by more than 10 %. The IMO AFS Convention has banned organotin biocides such as tributyltin (TBT) since 2008 and cybutryne since 2023; today’s systems are copper-oxide self-polishing copolymer (SPC) paints and biocide-free silicone fouling-release coatings. In the EU, biocidal paints also need authorisation under the Biocidal Products Regulation (BPR), and ships must carry an AFS certificate.