Marine Steel Plate Procurement: What Shipyards Should Check Before Ordering

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A steel plate order can look correct on a purchase order and still stop a vessel project. The usual causes are a substituted grade, a certificate that cannot be traced to the plate, a thickness tolerance that does not match the approved drawing, or delivery in the wrong sequence. This guide is for owners, procurement teams and shipyard managers who need to buy marine steel with fewer surprises.

For project and procurement teams

Start with the approved material schedule, not a supplier catalogue. Record the hull location, grade, nominal thickness, plate dimensions, quantity, delivery sequence and required classification society approval. AH36, DH36 and EH36 are not interchangeable simply because they are all high-strength hull steels: the design temperature, impact-test requirement and approved welding procedure determine whether a substitution is acceptable. Sea Keepers can reconcile the material schedule against production drawings before an RFQ is issued.

Technical checks for engineers

Request the mill test certificate for every heat and plate bundle. Check the heat number, cast number, grade, thickness, yield and tensile values, elongation, Charpy impact temperature and test results. For thicker or highly stressed members, the class rules may impose additional through-thickness or brittle-fracture requirements. IACS Recommendation 197 extends guidance for hull structural steels above 100 mm and up to 200 mm, showing why thickness and design temperature must be reviewed together rather than treated as a catalogue field.

Comparing common hull-steel choices

AH36 is a common normal-temperature higher-strength option; DH36 adds a lower impact-test temperature; EH36 is selected where still greater toughness is required. The right choice depends on the approved scantlings, operating environment and class review. Buying the cheapest grade can create redesign, retesting and welding delays that cost more than the plate saving. A compliant alternative must be approved by the responsible naval architect and classification society before fabrication.

Documents and delivery controls

Put certificate format, heat traceability, marking method, dimensional tolerances, inspection hold points and packing requirements in the RFQ. Ask the supplier to provide a plate list linked to each certificate, photographs before dispatch and a delivery plan that follows the shipyard's cutting and block sequence. On arrival, quarantine plates with missing marks or damaged certificates; do not allow them into nesting until QA clears the discrepancy.

Sea Keepers supports marine steel sourcing, production CAD coordination, material traceability and shipyard fabrication planning. Send us the approved material schedule for a procurement review before placing the international order.