Grade selection guide
Which grade do I need?
A starting point if you know the application but not the grade designation. Every row links to the grade page with full mechanical properties. If your case does not fit any row, send the specification directly.
ZCMetals supplies shipbuilding steel plate, bulb flat bar and sections — used across the vessel types below.
Where our products are used
The same grades cover different vessel types. Larger, higher-value ships generally call for the higher-strength AH/DH/EH series; smaller or less demanding vessels are often built in normal-strength grades.
Roughly where on the vessel
A simplified hull cross-section showing where these grades are typically specified. Higher-toughness grades (marked in orange) go on the zones under the most local stress.
- Hatch corners
- The highest local stress on a bulk carrier or container ship deck — the corners of the cargo hatch opening.
- Bilge strake
- Where the bottom shell curves into the side shell — a stress concentration from the change in curvature.
Illustrative, not a structural drawing for any specific vessel. Actual grade and thickness assignment follows the classification society's approved plans for that ship.
AH36 is not A36
These are two different standards. AH36 is a shipbuilding steel grade under classification-society rules (IACS), with chemistry and impact-testing requirements set by the society. A36 is an ASTM structural steel grade (ASTM A36/A36M) used in general construction, with no classification-society approval and no impact-testing requirement by default. The two are not interchangeable on a classed vessel — check which standard your project actually specifies before ordering.
By application
For cases this diagram does not cover — repairs, non-shipbuilding structures — see the full list below.
| Application | Grade | Why |
|---|---|---|
| General shell plating, decks and bulkheads, ambient service | No low-temperature impact testing specified. | |
| Primary hull structural members, general notch-toughness requirement | Impact tested at 0°C. | |
| Weather deck, sheer strake, bilge strake and other higher-stress normal-strength members | Impact tested at −20°C. | |
| Critical structural members, ice-class or cold-climate service | Impact tested at −40°C — the highest toughness requirement among normal-strength grades. | |
| Larger bulk carriers, tankers and container ships — thinner plate at the same strength | Higher yield than Grade A/B, impact tested at 0°C. | |
| Higher-strength structural members in lower service temperatures | Impact tested at −20°C. | |
| Critical higher-strength members, cold-climate or Arctic service | Impact tested at −40°C — the highest toughness requirement among higher-strength grades. | |
| Hull framing and stiffeners | Bulb flat bar | Bulb flat sections, matched to the plate grade in the same structure. |
| Repair or patch plates matching an existing hull | Application-dependent | Match the vessel's original specification. Send the classification certificate or ask your surveyor if it is not on hand. |
| Barges, pontoons, floating docks, port structures, general steel fabrication (not classed hull) | Application-dependent | Classification-society ship grades and general structural steel (for example ASTM A36) are different standards. Confirm which one your project specifies before ordering. |
Not sure which of these applies?
Send the drawing, class notation or intended service, and a grade recommendation comes back with the enquiry response.