Overview
A/B/D/E notation is used within normal-strength hull structural steel systems. The letter relates to toughness and testing context under the governing rules; it does not by itself define a universal substitute or a finished purchasing specification.
Designation and acceptance
IACS Unified Requirements are minimum classification-society requirements. Grade notation, thickness, delivery condition, test temperature, plate approval and the ship’s class rules must be read together; notation alone does not create an interchangeable material approval.
Members and selection
| Designation | Selection context |
|---|---|
| A | Normal-strength notation subject to the required member location, thickness and class-approved delivery condition. |
| B | Normal-strength notation requiring the project rule and test requirements to be checked. |
| D/E | Toughness-related notation; confirm impact-test temperature, thickness and delivery condition rather than assuming direct substitution. |
Comparison framework
| Criterion | Decision context |
|---|---|
| Selection basis | Normal-strength hull members still require member-specific grade selection under the classification rules. |
Performance
- A, B, D and E are normal-strength hull-steel designations whose toughness/test context changes with letter, thickness and rule application; the approved hull-member schedule remains decisive.
Orderable product scope
- Shipbuilding plate, wide flat and sections must be quoted with class approval, grade notation, thickness, delivery condition, inspection and material certificates.
Processing
- Preserve plate identity through nesting and cutting, and qualify welding for the actual grade, thickness, joint and approved shipyard procedure; normal strength does not waive repair or NDT controls.
Applications
- Hull structural members and marine structures where the design, classification and fabrication documents approve the ordered steel.
Selection
- Map deck, side shell, bottom, bulkhead and other hull-member locations to the class rule before choosing A/B/D/E; do not upgrade or substitute by letter alone.
Procurement
- Order the exact A/B/D/E notation with class society, approved mill, member use, thickness, delivery condition, impact-test requirement, certificate and traceability plan.