Classification societies · Steel grades · Rule references
Classification societies and their material rules
The class society named in the project documents sets the applicable classification rules and material certification requirements. For a plate order, confirm the mill approval scope and the evidence required for the supplied material.
ABS · American Bureau of Shipping
Rule reference ABS Rules for Materials and Welding, Part 2. For an ABS order, confirm the hull steel grade and the required material certification under the project’s ABS rules.
CCS · China Classification Society
Rule reference CCS Rules for Materials and Welding. For a CCS order, state the applicable rules edition and confirm the grade, plate dimensions and document requirements.
DNV
Rule reference DNV-RU-SHIP, Part 2, Chapter 2, Metallic materials. Use the project’s DNV rule reference. If the purchase documents use the historical DNV GL name, check the specified edition and designation with the yard.
LR · Lloyd’s Register
Rule reference LR-RU-002, Rules for the Manufacture, Testing and Certification of Materials. For an LR order, check the scope of the approved material and the inspection evidence required by the project.
BV · Bureau Veritas
Rule reference NR216, Rules on materials and welding for the classification of marine units. For a BV order, read NR216 with the classification rules for the unit and confirm the material certification scope.
See the guide to class certification for approval, survey and certificate checks.
Grade A, B, D, E and the AH36 to FH36 family
The four normal-strength grades below share a 235 MPa minimum yield strength in IACS UR W11 Rev.9 Table 6. The four higher-strength grades share the 355 MPa minimum in Table 7. Within each family, the grade letters distinguish the impact-test categories.
| Grade | Minimum yield | Charpy test temperature | Reading the grade |
|---|---|---|---|
| Grade A | 235 MPa | +20 °C where required | Table 6 lists no tabulated impact energy for plate up to 50 mm. Check the thickness and delivery-condition notes for thicker plate. |
| Grade B | 235 MPa | 0 °C where required | Charpy tests are generally not required for Grade B at 25 mm or less under Table 6. Confirm the order requirements. |
| Grade D | 235 MPa | −20 °C | Normal-strength Grade D has a lower tabulated impact-test temperature than Grade B. |
| Grade E | 235 MPa | −40 °C | Normal-strength Grade E is in the −40 °C impact-test category under Table 6. |
| AH36 | 355 MPa | 0 °C | The 36 strength level with the A impact category, shown as A36 in W11 Table 7. |
| DH36 | 355 MPa | −20 °C | The 36 strength level with the D impact category, shown as D36 in W11 Table 7. |
| EH36 | 355 MPa | −40 °C | The 36 strength level with the E impact category, shown as E36 in W11 Table 7. |
| FH36 | 355 MPa | −60 °C | The 36 strength level with the F impact category, shown as F36 in W11 Table 7. |
Check the table notes for impact-test exemptions and the required energy by thickness and specimen direction. Test temperature is a laboratory condition. The vessel’s design temperature and permitted grade come from the approved design and rules.
For test details, read the Charpy impact testing guide or the guide to selecting hull steel grades.
IACS requirements, class rules and ASTM specifications
IACS UR W11 · Hull structural steel
The International Association of Classification Societies (IACS) publishes common requirements that its member societies implement in their rules. W11 covers normal- and higher-strength hull structural steel. IACS lists Rev.9 (May 2017) as the current revision in the November 2026 review and schedules Rev.10 (September 2025) to enter into force on 1 January 2027. Check the project’s applicable edition and implementation dates.
IACS UR W13 · Thickness tolerances
W13 Rev.7 (September 2021) covers thickness tolerances of in-scope hull steel plates and wide flats. For its dimensional scope, measurement basis and exceptions, see the plate dimensions and tolerances guide.
ASTM A131/A131M · Structural steel for ships
ASTM A131/A131M is a material specification. When it appears on the purchase order, specify the required edition and grade, and confirm any separate class survey or certificate requirements.
What to put on the purchase order
Start with the yard’s approved material schedule. State the class society, steel grade, rule or material specification and edition. Add plate thickness, width and length, quantity, delivery condition, certificate and any extra testing. For example, an enquiry for LR AH36 still needs the plate sizes, quantities and the required inspection documents before the order can be confirmed.
Check the required certificate against the purchase order and match the heat or plate number to the material markings. Read the mill test certificate checklist for a document review, or send your material schedule if you need a quotation.
Frequently asked questions
Are ABS, CCS, DNV, LR and BV steel grades?
They are classification societies. AH36 or EH36 is the grade. The order must also identify the applicable rules and the certification required for the material.
What does 36 mean in AH36, DH36, EH36 and FH36?
In the cited IACS W11 tables, the 36 strength level has a minimum yield strength of 355 MPa. The letters identify the impact category, with test temperatures of 0, −20, −40 and −60 °C respectively. Acceptance also depends on the rule notes, plate thickness and specimen direction.
Can plate certified by one class society replace plate specified by another?
Confirm the proposed change with the yard and the parties responsible for class acceptance before purchasing. Matching grade names do not by themselves demonstrate that the approval, survey or certificate requirements are satisfied.
Technical sources and specification notes
- IACS UR W11 · Normal and higher strength hull structural steels — Rev.9 (May 2017), §6, Tables 6 and 7; Rev.10 (September 2025), implementation note
Use the revision and table notes applicable to the project. - IACS UR W13 · Thickness tolerances of steel plates and wide flats — Rev.7 (September 2021), §§1 and 3–5
Applies within the stated product and dimensional scope. - American Bureau of Shipping · Rules for Materials and Welding — ABS rules and rule changes, Materials and Welding, Part 2
Confirm the project edition in ABS Rule Manager. - China Classification Society · Rules for Materials and Welding — CCS Materials and Equipment rule index; 2026 edition effective 1 July 2026
Apply the edition and amendments identified in the project. - DNV · Rules for Classification of Ships — DNV-RU-SHIP, Part 2, Chapter 2, Metallic materials
Use the rules explorer to identify the applicable edition. - Lloyd’s Register · Rules for the Manufacture, Testing and Certification of Materials — LR-RU-002; 1 July 2026 edition listed
Check material scope and applicable rule changes for the project. - Bureau Veritas · Rules on materials and welding for the classification of marine units — NR216 R17 (January 2025), public rule listing
Read together with the classification rules for the marine unit. - ASTM A131/A131M · Standard Specification for Structural Steel for Ships — A131/A131M-19 public scope
Specify the contracted ASTM edition and any separately required class evidence.