Shipbuilding & Offshore Steel
Ship plate carries its papers with it: every plate is registered with a class society. Grades A through E correspond to +20 down to -40°C impact; AH32 to EH40 add strength levels of 315/355/390 MPa. Offshore structures add Z grades and tighter UT. The system is strict because hulls cannot fail gracefully.
| Class | Thickness mm | Impact temp. | Notes |
|---|---|---|---|
| A / B / D / E | 6–100 | +20 / 0 / -20 / -40°C | normal-strength hull steel |
| AH32 / DH32 / EH32 | 6–100 | 0 / -20 / -40°C | yield ≥315 MPa |
| AH36 / DH36 / EH36 | 6–100 | 0 / -20 / -40°C | yield ≥355 MPa |
| AH40 / DH40 / EH40 | 6–80 | 0 / -20 / -40°C | yield ≥390 MPa |
| FH32–FH40 | 6–80 | -60°C | polar & special duty |
| Z25 / Z35 add-on | by thickness | — | through-thickness properties |
Typical applications
Ordering notes
The core of ship plate is certification and traceability: mills produce to class rules, surveyors witness testing, certificates follow the goods. Confirm the target society (CCS, ABS, LR, DNV, BV, NK, KR) and certificate form — societies do not interchange.
For offshore orders to GB/T712 or referenced API/EN10225, watch UT class, Z-grade reduction of area and CEV ceilings; pipe-making coil plate should state impact sampling direction and count. Export hull plate ships with English mill certificates for destination clearance.
常见问答
What does DH36 mean?
D is the -20°C impact class, H36 the high-strength 355 MPa band — DH36 is -20°C, 355 MPa hull steel, heavily used in bulk-carrier and container-ship blocks.
Is a class certificate always required?
Classed hull structure needs it, surveyor-witnessed. Non-classed structures (port machinery, onshore steel) can take the same grades under ordinary mill certification at lower cost — the design document decides.
When are Z grades needed?
Where welds pull through-thickness — hatch coamings, transverse bulkhead joints, offshore nodes. Z15/Z25/Z35 state the minimum through-thickness reduction of area; verify the values on the certificate.
Further reading
A few related pieces worth a look: