Carbon Steel Plate: ASTM A516 & A36 — Grades, Specifications & Applications
Carbon steel plate is the starting material for pressure vessels, storage tanks, heat exchangers, boilers, structural steel frames, and heavy equipment across every industrial sector. A refinery builds its reactors and columns from it. A tank farm stores millions of liters of product in it. A bridge transfers load through it. A crane operates on frames fabricated from it.
Two specifications dominate carbon steel plate procurement: ASTM A516 for pressure vessel and boiler fabrication, and ASTM A36 for structural and general-purpose applications. They are both carbon steel, but they are engineered for fundamentally different jobs — and specifying the wrong one can mean a failed pressure test, a rejected inspection, or a structural design that does not meet code.
This guide covers both specifications, their grades, properties, differences, and how to specify the right plate for your fabrication project.
ASTM A516 — Pressure Vessel Plate
ASTM A516 is the standard specification for carbon steel plates intended for welded pressure vessels operating at moderate and lower temperatures. It is the most commonly specified plate for pressure vessel and boiler fabrication worldwide. The ASME Boiler and Pressure Vessel Code equivalent is SA516.
Grades and Mechanical Properties
ASTM A516 covers four grades, designated by their minimum tensile strength in ksi (thousands of pounds per square inch):
Property | Grade 55 | Grade 60 | Grade 65 | Grade 70 |
|---|---|---|---|---|
Min. tensile strength | 380 MPa (55 ksi) | 415 MPa (60 ksi) | 450 MPa (65 ksi) | 485 MPa (70 ksi) |
Min. yield strength | 205 MPa (30 ksi) | 220 MPa (32 ksi) | 240 MPa (35 ksi) | 260 MPa (38 ksi) |
Elongation in 200mm, min | 27% | 25% | 23% | 21% |
Max. carbon (≤12.5mm) | 0.18% | 0.21% | 0.24% | 0.27% |
Max. carbon (>12.5–50mm) | 0.20% | 0.23% | 0.26% | 0.28% |
Max. carbon (>50–100mm) | 0.22% | 0.25% | 0.28% | 0.30% |
Manganese range | 0.60–0.90% | 0.85–1.20% | 0.85–1.20% | 0.85–1.20% |
Grade 70 is what you need in 80% of cases. It provides the highest strength, making it the most efficient choice (thinner plates can be used for the same pressure rating, saving material and weight). When someone says "A516 plate" without specifying the grade, they almost always mean Grade 70.
Grade 60 and 65 are used when the design requires better formability or weldability than Grade 70 — the lower carbon content of these grades reduces the risk of weld cracking in thick sections.
Grade 55 is used for the lowest-temperature applications and where maximum ductility is required.
Chemical Composition (All Grades)
In addition to carbon and manganese (which vary by grade), the following elements apply to all A516 grades:
Element | Maximum |
|---|---|
Phosphorus (P) | 0.035% |
Sulfur (S) | 0.035% |
Silicon (Si) | 0.15–0.40% |
Killed steel practice is mandatory — A516 plates must be made from fully killed steel (deoxidized with silicon or aluminum) to ensure a homogeneous, sound plate free from gas porosity.
Heat Treatment
Normalizing is required for A516 plates above certain thicknesses (varies by grade, but generally above 40mm for Grade 70). Normalizing involves heating the plate above its critical temperature (~900°C) and air cooling. This refines the grain structure and improves toughness — particularly important for pressure vessels that must resist brittle fracture.
For plates up to 40mm thick, A516 Grade 70 can be supplied as-rolled. For thicker plates or when the project specification requires it, normalized delivery is specified.
Post-weld heat treatment (PWHT) may be required by the applicable pressure vessel code (ASME Section VIII) after welding, depending on the plate thickness and the service conditions. PWHT relieves residual welding stresses and improves the toughness of the weld heat-affected zone.
Key Applications
Pressure vessels (ASME Section VIII) — the primary application
Industrial boilers (ASME Section I)
Storage tanks (API 650 for atmospheric, API 620 for low-pressure)
Heat exchanger shells and channels
Columns, reactors, and drums in refinery and petrochemical plants
LPG and ammonia storage spheres
Deaerators and feedwater heaters in power plants
ASTM A36 — Structural Steel Plate
ASTM A36 is the most widely used structural steel specification in the world. It covers carbon structural steel shapes, plates, and bars for general structural applications — buildings, bridges, machinery, and fabricated structures.
Mechanical Properties
Property | A36 |
|---|---|
Min. tensile strength | 400–550 MPa (58–80 ksi) |
Min. yield strength | 250 MPa (36 ksi) |
Elongation in 200mm, min | 23% |
Max. carbon (≤20mm) | 0.25% |
Max. carbon (20–40mm) | 0.25% |
Max. carbon (40–65mm) | 0.26% |
Max. carbon (65–100mm) | 0.27% |
Manganese | — (no minimum, typical 0.60–0.90%) |
Phosphorus max | 0.04% |
Sulfur max | 0.05% |
Silicon | 0.40% max |
A36 is mild steel — it has lower strength than A516 Grade 70 but excellent ductility, weldability, and machinability. It is the default material for structural steel fabrication when the design does not involve pressure containment.
Key Applications
Building frames and structural columns
Bridge components (plate girders, connection plates)
Machinery bases and equipment supports
Crane structures and lifting equipment
Ship and barge construction
Transmission tower components
General fabrication and base plates
Anchor bolt and embed plates for concrete
A516 Grade 70 vs A36: Head-to-Head Comparison
This is the comparison buyers search for most. Here is the definitive guide:
Factor | A516 Grade 70 | A36 |
|---|---|---|
Primary purpose | Pressure vessel fabrication | Structural steel fabrication |
ASME code | SA516 Gr 70 (Sec VIII, Sec I) | Not a pressure vessel material |
Min. yield strength | 260 MPa (38 ksi) | 250 MPa (36 ksi) |
Min. tensile strength | 485 MPa (70 ksi) | 400 MPa (58 ksi) |
Carbon content | Tightly controlled per thickness | Loosely controlled |
Sulfur / phosphorus | Lower max (0.035% each) | Higher max (S: 0.05%, P: 0.04%) |
Steel making | Killed steel mandatory | Killed or semi-killed |
Normalizing | Required above ~40mm thickness | Not typically required |
Impact testing | Available (Charpy V-notch per ASME) | Not standard |
Notch toughness | Designed for good toughness | Not specifically designed for it |
Ultrasonic testing | Often specified (ASTM A578) | Not typically required |
Traceability | Full heat traceability required | May not have full traceability |
Cost | 10–20% higher than A36 | Lower cost (most economical CS plate) |
Can be used for pressure vessels? | Yes — designed for it | No — not a PVQ material |
Can be used for structures? | Yes — but more expensive than necessary | Yes — designed for it |
The critical rule: You cannot substitute A36 for A516 in pressure vessel fabrication. A36 does not meet the steel-making, testing, and traceability requirements of ASME Section VIII. Using A36 in a pressure vessel will result in failed inspection and code non-compliance.
You can use A516 for structural applications — it exceeds A36 in every mechanical property. But this is wasteful because you pay the A516 premium (10–20% more) for properties you do not need.
Simple decision: Pressure vessel, boiler, or tank → A516. Structure, frame, or machine base → A36.
Other Common Carbon Steel Plate Specifications
Specification | Purpose | Typical Use |
|---|---|---|
ASTM A283 | Low/intermediate tensile CS plate | Storage tanks, structural, general fabrication |
ASTM A285 | PVQ plate for lower-pressure vessels | Low-pressure vessels, not for high-temperature |
ASTM A515 | PVQ plate for higher-temperature service | Vessels operating at moderate-high temperatures |
ASTM A537 | PVQ plate with improved toughness | Vessels requiring enhanced notch toughness |
ASTM A572 Gr 50 | High-strength low-alloy structural plate | Bridges, buildings, structural applications requiring higher strength than A36 |
ASTM A573 | Structural CS plate with improved toughness | Structural applications requiring Charpy impact testing |
For most projects in Africa and the Middle East: A516 Grade 70 covers 80%+ of pressure vessel plate requirements. A36 covers 80%+ of structural plate requirements. These two specifications handle the vast majority of carbon steel plate procurement.
Available Sizes
Parameter | A516 Grade 70 | A36 |
|---|---|---|
Thickness | 6mm to 200mm (1/4" to 8") | 3mm to 200mm (1/8" to 8") |
Width | 1,500mm, 2,000mm, 2,500mm, 3,000mm | 1,219mm (4'), 1,500mm, 2,000mm, 2,500mm |
Length | 6,000mm, 8,000mm, 12,000mm | 2,438mm (8'), 6,000mm, 12,000mm |
Delivery | As-rolled or normalized | As-rolled (hot-rolled) |
Surface | Mill scale (standard) | Mill scale (standard) |
Custom cutting — plates can be plasma cut, flame cut, or laser cut to your fabrication drawings, reducing waste and workshop labor.
What Documentation to Request
EN 10204 Type 3.1 Mill Test Certificate (MTC) — minimum requirement. Must show heat number, chemical composition (actual analysis), mechanical test results (tensile, yield, elongation), and plate dimensions. For A516, the MTC must also confirm killed steel practice.
Charpy V-notch impact test results — required by ASME Section VIII for many pressure vessel applications, particularly at design temperatures below ambient. Specify the test temperature per the design code (typically 0°C, -20°C, or -46°C depending on the minimum design metal temperature).
Ultrasonic testing (UT) — per ASTM A578 (straight beam) or ASTM A435 (full plate scanning). Required for critical pressure vessel applications to detect internal laminations, inclusions, or segregation that could cause lamellar tearing during welding.
Normalized certification — if the plate is specified as normalized, the MTC must confirm the normalizing temperature and that the plate was air-cooled from above the critical temperature.
Third-party inspection (TPI) — for critical projects, independent inspection by Bureau Veritas, SGS, TÜV, or Lloyd's Register during production and before shipment.
How to Order Carbon Steel Plate
1. Specification: ASTM A516 (pressure vessel) or ASTM A36 (structural)
2. Grade: A516 Grade 55, 60, 65, or 70 / A36 (single grade)
3. Thickness: In mm or inches
4. Dimensions: Width × length in mm or feet/inches. Specify if exact-cut dimensions are required.
5. Quantity: Number of plates, or total weight in metric tonnes
6. Heat treatment: As-rolled or normalized (specify for A516 above 40mm or per project spec)
7. Testing: Standard (tensile + chemistry) or supplementary (add Charpy impact, UT, bend test)
8. Documentation: EN 10204 Type 3.1 minimum. Add TPI if required.
9. Edge condition: Mill edge, sheared, or flame-cut
10. Marking: Heat number stamped, paint-stenciled, or both
Example order:
20 pcs — ASTM A516 Grade 70, Normalized, 25mm × 2,000mm × 6,000mm, with Charpy V-notch impact test at -20°C, UT per ASTM A578 Level B, EN 10204 Type 3.1 MTC. Third-party inspection by Bureau Veritas.
Supply from Kasko Makine
Kasko Makine supplies carbon steel plate for pressure vessel fabrication, structural steel construction, and general industrial projects:
Pressure vessel plate: ASTM A516 Grade 55, 60, 65, and 70 / ASME SA516. As-rolled and normalized. Thickness 6mm to 200mm. With Charpy impact testing and UT inspection per project specification.
Structural plate: ASTM A36, A283 Grade C, A572 Grade 50. Thickness 3mm to 200mm. Standard widths and lengths, plus custom cutting.
Cutting services: Plasma, flame, and laser cutting to your fabrication drawings. Beveling for weld preparation available.
We also supply the stainless steel plate (304, 316, 321), alloy steel plate (A387, 12Cr1MoVR), pipe, flanges, fittings, and fasteners needed for your fabrication project — complete material packages from a single source.
All plate supplied with EN 10204 Type 3.1 mill test certificates. Charpy impact testing, UT inspection, and third-party verification available on request.
FAQ SCHEMA
Q: What is the difference between ASTM A516 Grade 70 and A36 plate?
A: A516 Grade 70 is a pressure vessel quality (PVQ) plate designed for welded pressure vessels and boilers — it has controlled chemistry, mandatory killed steel, and is often supplied normalized with impact testing. A36 is a structural steel plate for buildings, bridges, and general fabrication. A36 cannot be used for pressure vessels because it does not meet ASME code requirements. A516 Gr 70 is 10–20% more expensive but necessary for any pressure-containing application.
Q: What is ASTM A516 Grade 70 used for?
A: A516 Grade 70 is primarily used for fabricating welded pressure vessels, industrial boilers, storage tanks (API 650/620), heat exchanger shells, and process equipment in the oil and gas, petrochemical, power generation, and chemical industries. It provides excellent notch toughness for moderate and lower temperature service.
Q: What does "normalized" mean for steel plate?
A: Normalizing is a heat treatment where the plate is heated above its critical temperature (~900°C) and then air-cooled. This refines the grain structure, improves toughness and ductility, and produces more uniform mechanical properties throughout the plate thickness. Normalizing is required for A516 plates above approximately 40mm thickness and is often specified for critical pressure vessel applications regardless of thickness.
Q: What is the ASME equivalent of ASTM A516?
A: ASME SA516 is the ASME Boiler and Pressure Vessel Code equivalent of ASTM A516. The chemical and mechanical properties are identical. SA516 is referenced in ASME Section VIII (pressure vessels) and Section I (boilers). Plates used in ASME code-stamped equipment must be produced and certified under the SA516 designation.
Q: Can I use A36 plate for a pressure vessel?
A: No. ASTM A36 is not a pressure vessel quality material and does not meet the requirements of ASME Section VIII. It lacks the mandatory killed steel practice, controlled chemistry, traceability, and impact testing required for pressure vessel fabrication. Using A36 in a pressure vessel will result in failed inspection and code non-compliance. Always use A516 (or equivalent PVQ specification) for pressure-containing equipment.
Q: What testing should I request for A516 Grade 70 plate?
A: At minimum, an EN 10204 Type 3.1 Mill Test Certificate showing heat number, chemical composition, and tensile test results. For critical pressure vessel applications, also request Charpy V-notch impact testing at the design temperature (0°C, -20°C, or -46°C per code), ultrasonic testing per ASTM A578, and normalized delivery certification. Third-party inspection is recommended for high-value orders.
Request carbon steel plate pricing — send us your specification, grade, thickness, dimensions, quantity, and any special requirements (normalizing, impact testing, UT, cutting) to info@kaskomakine.com or WhatsApp +90 (537) 521 1399. We respond within 24 hours and deliver to fabrication shops and project sites across Africa, the Middle East, Central Asia, and beyond.