ASTM A131 Shipbuilding Quality Steel Plate
ASTM A131 is a steel plate structural grade used exclusively in the shipbuilding industry. This grade is defined as ordinary strength, with a minimum yield strength of 34KSI (235Mpa).
The ASTM A131 standard is divided into two main categories:
- Ordinary Strength: Grades A, B, D, and CS.
- Higher Strength: Grades AH32, DH32, EH32, FH32, AH36, DH36, EH36, FH36, AH40, DH40, EH40, and FH40.
Welding Cost Reduction:The carbon equivalent of standard EH36 steel plates is usually close to the specification upper limit of 0.38%–0.40%. By contrast, our optimized ASTM A131 composition stably controls the carbon equivalent (Ceq) at ≤0.35%. This directly lowers the preheating temperature before welding from 100℃–150℃ to 50℃, cutting preheating energy consumption and working hours of each hull section by 30%–50%.
Dimensional Accuracy:The actual delivery flatness of our ASTM A131 Grade A steel is controlled within ≤3 mm/m. It reduces thermal correction workload by over 70% and completely eliminates CNC cutting flameout and shutdown issues caused by poor plate shape.
Lead Time Optimization:Supported by high rolling force for large single-weight production and a full-coverage pretreatment production line covering 5–30 mm thickness, the steel plate achieves Sa 2.5 grade sandblasting and derusting, with surface roughness precisely controlled at 40–75 μm, and finished with 15–25 μm shop primer coating.
Extreme Low-Temperature Toughness:Our F-grade steel plates have passed impact tests at -60℃, with the fibrous fracture toughness ratio consistently maintained above 85%. In addition, Z35 grade lamellar tearing resistant steel features a thickness-direction reduction of area (ψz) of 35%–50%, more than three times that of ordinary steel plates, fundamentally eliminating the risk of lamellar tearing at key structural joints.
The ASTM A131 standard ship plate grades we can provide include:
|
A131 Steel Plate Grade |
||||
|
General Strength |
Grade A |
Grade B |
Grade D |
Grade E |
|
High Strength |
A131 AH32 |
A131 DH32 |
A131 EH32 |
A131 FH32 |
|
A131 AH36 |
A131 DH36 |
A131 EH36 |
A131 FH36 |
|
|
A131 AH40 |
A131 DH40 |
A131 EH40 |
A131 FH40 |
|
ASTM A131 standards shipbuilding steel plate chemical composition
| Element | Chemical composition(heat analysis% max | |
| AH/DH/EH32 AH/DH/EH36 and AH/DH/EH40 | FH32/36/40 | |
| C | 0.18 | 0.16 |
| Mn | 0.90-1.60 | 0.90-1.60 |
| Si | 0.10-0.50 | 0.10-0.50 |
| P | 0.035 | 0.025 |
| S | 0.035 | 0.025 |
| Al min | 0.015 | 0.015 |
| Cb | 0.02-0.05 | 0.02-0.05 |
| V | 0.05-0.10 | 0.05-0.10 |
| Ti | 0.02 | 0.02 |
| Cu | 0.35 | 0.35 |
| Cr | 0.20 | 0.20 |
| Ni | 0.40 | 0.40 |
| Mo | 0.08 | 0.08 |
| N | - | 0.009 |
ASTM A131 standards steel plates for shipbuilding tensile requirement
| Grade | Tensile Strength ksi(Mpa) | Yield Strength min ksi(Mpa) | Elongation in 8 in (200mm) % | Elongation in 2 in (50mm) min % |
| Ordinary strength | 58-75(400-520) | 34(235) | 21 | 24 |
| A B D E CS | ||||
| Higher strength | ||||
| AH32 DH32 EH32 FH32 | 64-85(440-590) | 46(315) | 19 | 22 |
| AH36 DH36 EH36 FH36 | 71-90(190-620) | 51(355( | 19 | 22 |
| AH40 DH40 EH40 FH40 | 74-94(510-650) | 57(390) | 19 | 22 |
ASTM a131 standards marine sheet applications
1. Build various types of ships such as cargo ships, oil tankers, and passenger ships to provide structural support for the ships.
2. Used in various other marine applications such as offshore platforms, marine pipelines and other underwater structures.
3. Used in the construction of naval ships, submarines and other military vessels.
Equivalent Grades & Global Standards
ASTM A131 is often cross-certified with classification society standards. GNEE STEEL provides plates that meet both ASTM A131 and the equivalent rules of:
- ABS (American Bureau of Shipping)
- LR (Lloyd's Register)
- BV (Bureau Veritas)
- DNV (Det Norske Veritas)
- CCS (China Classification Society)
| ASTM A131 Grade | ABS Equivalent | LR Equivalent | DNV Equivalent |
| ASTM A131 Grade A | ABS Grade A | LR Grade A | DNV Grade A |
| ASTM A131 AH36 | ABS AH36 | LR AH36 | DNV AH36 |
| ASTM A131 EH36 | ABS EH36 | LR EH36 | DNV EH36 |
ASTM A131 vs. ASTM A36
A common question is: Can I use A36 instead of A131 Grade A?
- A36: A general structural steel with no specific requirements for maritime impact toughness.
- A131 Grade A: Specifically tested and certified for shipbuilding. It includes stricter controls on chemical elements to ensure better performance in marine welding and vibration environments. For marine vessels, ASTM A131 is the mandatory safety choice.
FAQ
Can GNEE provide plates with Z-direction (through-thickness) properties?
Yes, we provide ASTM A131 steel with Z15, Z25, and Z35 testing to prevent lamellar tearing in high-stress joints.
What surface treatments do you offer?
We offer shot-blasting to SA2.5 and pre-painting with inorganic zinc shop primers to prevent rust during fabrication.
Do you provide mill test certificates?
Absolutely. All ASTM A131 plates come with full traceability and 3.1 or 3.2 MTCs (Material Test Certificates).
What is ASTM A131 material?
The ASTM A131 specification is the Standard Specification for Structural Steel plates primarily used in ship construction. Steel grades covered in this specification require CVN Impact testing and are classified by minimum Yield Strengths.
What is the yield strength of ASTM A131 DH36?
51 ksi
ASTM A131 Grades AH36, DH36, and EH36 are higher-strength structural steels with a minimum specified yield strength of 51 ksi and specified minimum Charpy V-notch impact toughness properties.
Why Source ASTM A131 from GNEE STEEL?
Expertise: Over 18 years of experience in the international steel trade.
Large Inventory: We stock a wide range of thicknesses (from 5mm to 150mm) and widths (up to 4000mm).
Custom Processing: In-house plasma cutting, bending, and specialized welding services.
Global Logistics: Reliable shipping to any major port worldwide with seaworthy packaging.
Conclusion
ASTM A131 shipbuilding steel is the backbone of the global maritime industry. By choosing GNEE STEEL, you are partnering with a supplier that understands the critical nature of marine safety and structural integrity. Our ASTM A131 plates are built to last, from the coldest oceans to the most demanding offshore sites.
Launch Your Marine Project with Confidence!
Get a fast, competitive quote for your ASTM A131 steel requirements. Our technical team is standing by to help you choose the right grade for your specific hull or offshore design.
ASTM A131 standards hull plate Products image
GNEE group team photo
GNEE group customer visit
GNEE Group participates in foreign steel exhibitions
Our products have undergone strict quality testing and come with professional certificates. If you have any questions about ASTM A131 Shipbuilding Quality Steel Plate, please feel free to inspect.
Relying on many first-class equipment, such as CNC Shearing machine, Press Brake machine, Straightening machine, Roll Bending machine, Flat Bar Machine, Deburring machine etc, GNEE STEEL could provide various semi-productsand extensive forming services to customers.
GNEE STEEL PROCESSING
1.CTL & SL SERVICE (141 SETS)
Currently, GNEE STEEL has imported manyadvanced CTL/SL equipment from Italy and Korea and could provide customized CTL/SL services from cold rolled stainless steel and carbon steel to hot rolled stainless steel and carbon steel as well as strips and ultra-wide sheet.
CTL FACILITIES
Max Length:16500mm
Max Width:2200mm
Max Thickness:25.4mm
Max Yield Strength:1500Mpa
SL FACILITIES
Max Width:2200mm
Max Thickness:18mm
Max slit Quantity:31
Max Yield Strength:1200Mpa
2.CUTTING SERVICE
GNEE STEEL imported lots of advanced cutting machines from Germany, Sweden, America and Japan, including plasmas cutting machine, water jet cutting machine, laser cutting machine, flame cutting machine and saw machine. In order to meet customers' diversified needs, GNEE STEEL also adopts nest working multi-cutting methods and intensive production to improve production capacity and save costs for the customers.
Laser Cutting Machine
Max Cutting Length:40,000mm
Max Width:4,600mm
Max Thickness:100mm
Flame Cutting Machine
Max Cutting Length:40,000mm
Max Width:8,000mm
Max Thickness:500mm
Plasmas Cutting Machine
Max Cutting Length:30,000mm
Max Width:5,000mm
Max Thickness:100mm
Water-jet Cutting
Max Cutting Length:12,000mm
Max Width:4,010mm
Max Thickness:250mm
3.FORMING SERVICE
Steel Plate Roll Bending
Maximum Rolling Thickness: up to 200mm
Maximum Width: 4200mm
Automatic Bending Machine-Press Brake
Max Bending Capability:3000Ton
Max Bending Length:15,000mm
Expert in Bending High-Strength & Wear-Resistant Steels
Punching Machine
Max Width:3,070mm
Max Thickness:8mm
Max Pressure:250t
BEVELING SERVICE
GNEE STEEL beveling platform has edge milling machine, edge planer, flame / plasma groove cutting machine, flame groove cutting robot, desktop chamfering machine, gantry planerand other advanced equipment to provide customers with parts prefabrication services,daily processing of V-type, Y-type, X-type and U-type grooves, and guarantee subsequent processes such as welding and assembly of products.
Milling：
Max Cutting Length:18,000mm
Max Width:4500mm
Max Thickness:120mm
Beveling:
Max Length:16,000mm
Max Thickness:80mm
MACHINING SERVICE
GNEE STEEL owns CNC Portal-type Boring and Milling machine,CNC Floor-type Boring and Milling machine, Vertical Precision 5-axis Milling Machine, Portal-type Planer, Vertical Lathe, Cylindical Grinding machine, Hydraulic Planer and CNC Lathe and could provide fine machining of large spare parts and structural parts for customers.
Gantry Type Boring & Milling Maching Center
Max Length:48000mm
Max Width:12500mm
Max Height:8000mm
Max Diameter:10500mm
Deep-hole Drilling Equipment
Max Driling Depth:1,100mm
Max Bore Diameter:φ80mm
Max Diametar:φ4,500mm
MMulti-hole Drilling Equipment
Max Length:13,000mm
Max Width:10,000mm
Max Bore Diameter:φ105mm
Max Drilling Depth:250mm
Floor Boring And Milling Machine
Max Length:24,000mm
Max Height:8,000mm
Turntable Dimensions:9x5m
Vertical Lathe
Max Height:6,000mm
Max Diametar:φ22,00mm
Automated Edge Milling Machine
The Automated Edge Milling Machine is a leading product in heavy-duty milling equipment. It is primarily used for weld groove preparation (beveling) on large-format plates made of stainless steel, carbon steel, and special steel grades. It can process plates with a maximum thickness of up to 90mm, a length of 16 meters, and a width of 4 meters.
It is equipped with dual milling units and a fully automatic milling cutter head changing system, enabling automated 4-edge beveling. Its standout feature is the profiling technology used when milling wavy plates and irregularly shaped products, which ensures absolute consistency of the groove after milling.
Utilizing specially designed milling cutter heads, it can execute highly difficult and complex groove profiles in a single pass.
Materials: Plain carbon steel, pressure vessel steel, wear-resistant steel, high-strength steel, stainless steel, nickel-based alloys, etc.
Width: 1200 - 4200 mm
Length: 5800 - 16000 mm
Thickness: 5 - 90 mm
Weight: Up to 35 tons
This edge milling machine is the world's premier automated bevel milling equipment. With its excellent structural design and advanced data algorithms, it achieves full automation from plate detection to the actual milling process, significantly improving processing efficiency while guaranteeing high precision.
- Processing Accuracy
Length accuracy: ±1mm when L < 10m; ±2mm when L > 10m;
Width accuracy: ±1mm;
Diagonal accuracy: ±2mm;
Root face accuracy (blunt edge): ±1mm for Y-grooves; +0.5mm for X-grooves.
- Processing Efficiency
The processing efficiency is more than 10 times that of conventional edge milling or edge planing equipment.
HEAT TREATMENT
Heat Treatment Furnace
Max Furnace Size:36x12x13.5m
Max Rated Temperature:1100℃
Max Loading Capacity:800t
Heat Treatment of Pressure Vessels
Heat Treatment of Mining Equipment
Heat Treatment of Tube Sheet
Heat Treatment of Pressure Vessel Head
Case : Steel Plates Supply for 100,000m³ Full Containment Ammonia Storage Tank Project
GNEE STEEL is currently participating in the procurement phase of a 100,000m³ full containment ammonia storage tank project, supplying high-quality steel plates for critical tank components. Due to the corrosive nature of ammonia and the risk of Ammonia Stress Corrosion Cracking (SCC), the project requires strict metallurgical control of materials according to EN 10028-3 standards.
One of the most important technical requirements of this project is the strict limitation of the actual Yield Strength (Re) for all NL2 grade materials. To prevent SCC risks in ammonia storage environments, the actual yield strength must not exceed 390 MPa, regardless of the nominal values specified in the standard or plate thickness ranges. This requirement places higher demands on steelmaking process control, heat treatment stability, and material testing.
Raw high-strength steel plates ready for the 100,000 m³ full containment ammonia storage tank production
Project Materials and Technical Requirements
The project mainly uses P355NL2 and P275NL2 normalized pressure vessel steel plates, which are widely applied in low-temperature storage tanks due to their excellent toughness and weldability.
Key technical specifications include:
- Material grades: P355NL2 and P275NL2 (Normalized)
- Yield strength: Standard minimum / Maximum limited to 390 MPa
- Hardness: ≤ 225 HBW in base material
- Impact testing: Charpy-V notch test at -50°C, minimum 27J
- Certification: EN 10204 3.1 certificate, with optional 3.2 certification
These strict requirements ensure that the steel plates maintain stable mechanical properties and high resistance to ammonia-induced stress corrosion during long-term operation.
Precision rolling and forming of steel plates into curved sections for the 100,000 m³ ammonia storage tank.
Project Plate Quantities and Thickness Distribution
The total steel demand for this ammonia storage tank project is several thousand tons, mainly distributed across different tank sections:
P355NL2 – Inner & Outer Tank Shell Plates
- Lower shell courses: 50 mm thickness – approx. 2,000 tons
- Middle shell courses: 25 mm thickness – approx. 1,400 tons
- Upper shell courses: 10 mm thickness – approx. 500 tons
P275NL2 – Tank Bottom Plates
- Thickness: 10–15 mm – approx. 750 tons
P275NL2 – Suspended Roof Structure
- Thickness: 5–8 mm – approx. 180 tons
S275JR – Outer Roof (Ambient Structure)
- Thickness: 10 mm – approx. 450 tons
To improve tank fabrication efficiency and reduce circumferential welds, the project also requires wide steel plates to minimize welding joints, which helps reduce the potential risk of SCC in ammonia service conditions.
Formed steel segments wrapped and racked for protection, ready for 100,000 m³ ammonia storage tank assembly.
GNEE STEEL provides high-precision steel plate rolling and cylinder fabrication solutions for tank manufacturers worldwide. Send us your plate specifications or fabrication drawings for a fast quotation.
| TYPE | GRADE | SPECIFICATIONS |
| Carbon Steel / Low Alloy Coil | Q235A/B/C/D/Q355B(Q345B)/C/D/E/SS400/SAPH400-C/ASTMA283Grade C |
0.7~2.0*1250/1500mm*C 2.3~19.5*1250/1500/1800/2000mm*C |
| Medium Heavy Plate | Q235B/Q355B(Q345B)/C/D/E | 6.0-200x150mm-4000mmxL |
| Vessel Plate |
Q245R/Q345R/HP295/SA516MGR485/SA516GR70/P355NL2/P275NL2/ S275JR//SPV490/ASTM A537 Class 1/Class 2 |
2.5-120x1500mm-3000mmxL |
| High Strength Steel |
510L/610L/700L/750L/BS600MCK4/BS700MCK2/BS700MCK4/ BS960E/BWELDY700QL2/L4/BWELDY960QL4/HG60D/70D/785D/ Q460D/Q550D/690D/690E/TQ600MCD/TQ700MCD/S700MCD/ WYS600/700/STRENX700MCE/Q490E/Q490D |
1.2-60x 1500mm-2500mmxL |
| Patterned Steel | HQ235A|B | 1.2-60x 1500mm-2500mmxL |
| Wear-resistance Steel |
NM360/400/450/500/NM300TP/400TP/450TP/ ABREX400/450/500/B-HARD450XKY/ CREUSABRO4800/8000/EH C400LE/450LE/500LE/ |
3.0-50x1250mm-3300mmxL |
| Cold Rolled Coil | DC01/RECC/REDT/SPCC/ST12 | 0.5-3.0x1250mm-1500mmxC |
| Galvanized Plate | DC51D+AZ/DC51D+Z/DX51D+Z/SGH340+Z275/Z275/Z120/S350GD+ZM275 | 0.45-3.0x1250mm-1500mmxC |
| Pickled Coil | DD11/SPHC | 2.0-6.0x1500xC |
Stainless Steel Material and Surface Specifications
| TYPE | GRADE | THICKNESS | SURFACE |
| Austenitic | 304/304H/304L/304J1 | 0.25-150mm | 2B/BA/NO.4/8K/SB/HL/NO.1 |
| Austenitic | 321 | 0.4-80mm | 2B/BA/NO.4/8K/SB/HL/NO.1 |
| Austenitic | 316/316L/317L/316Ti | 0.3-80mm | 2B/BA/NO.4/8K/SB/HL/NO.1 |
| Austenitic | 201(J1/J2/J5) | 0.35-12mm | 2B/NO.1/1D |
| Ferrite | 430 | 0.4-3.0mm | 2B/BA/NO.4/8K/SB/HL |
| Ultra Pure Ferrite | 443 | 0.4-2.0mm | 2B |
| Ultra Pure Ferrite | 436L/439/444/441 | 0.5-3.0mm | 2B/2D |
Special Steel / Nickel Base Alloy
| TYPE | GRADE | GRADE (ASTM) | GRADE (EN) | THICKNESS |
| Heat-resistant Steel | 309S | S30908 | 1.4833 | 0.5-40mm |
| Heat-resistant Steel | 310S | S31008 | 1.4845 | 0.5-40mm |
| Duplex Stainless Steel | 2101 | S32101 | 1.4162 | 1.5-50mm |
| Duplex Stainless Steel | 2304 | S32304 | 1.4362 | 3.0-50mm |
| Duplex Stainless Steel | 2205 | S32205/S31803 | 1.4462 | 0.5-60mm |
| Duplex Stainless Steel | 2507 | S32750 | 1.4410 | 1.0-60mm |
| Super Austenitic-Steel | 904L | N08904 | 1.4539 | 0.6-50mm |
| Super Austenitic-Steel | 254SMO | S31254 | 1.4547 | 0.5-50mm |
| Super Austenitic-Steel | 1.4529 | N08926 | 1.4529 | 0.5-50mm |
| Super Austenitic-Steel | AL-6XN | N08367 | 1.4478 | 0.5-50mm |
| Nickel Base Alloy | Alloy 31 | N08031 | 1.4562 | 1.0-50mm |
| Nickel Base Alloy | 800 | N08800 | 1.4876 | 0.8-50mm |
| Nickel Base Alloy | 800H | N08810 | 1.4958 | 0.8-50mm |
| Nickel Base Alloy | 800HT | N08811 | 1.4959 | 0.8-50mm |
| Nickel Base Alloy | Alloy 28 | N08028 | 1.4563 | 1.0-20mm |
| Nickel Base Alloy | Alloy 20 | N08020 | 2.4660 | 1.0-20mm |
| Nickel Base Alloy | 825 | N08825 | 2.4858 | 0.8-40mm |
| Nickel Base Alloy | C276 | N10276 | 2.4819 | 0.5-50mm |
| Nickel Base Alloy | C22 | N06022 | 2.4602 | 1.0-50mm |
| Nickel Base Alloy | 625 | N06625 | 2.4856 | 0.8-20mm |
| Nickel Base Alloy | 400 | N04400 | 2.4360 | 1.0-20mm |
| Nickel Base Alloy | 600 | N06600 | 2.4816 | 1.0-50mm |
| Nickel Base Alloy | Pure Ni 201 | N02201 | 2.4061 | 0.5-20mm |
| Titanium | TA1 | Gr.1 | Class 1 | 0.5-50mm |
| Titanium | TA2 | Gr.2 | Class 2 | 0.5-50mm |
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