A516 Grade 70, also written as ASTM A516 Grade 70 or ASME SA516 Grade 70, is a pressure vessel quality carbon steel plate used in welded equipment for moderate and lower temperature service. It is one of the most frequently specified plate grades for pressure-retaining components in refineries, petrochemical plants, power generation facilities, terminals, and general process industries because it combines dependable strength, good weldability, and improved notch toughness compared with many general structural carbon steels.
In practical terms, buyers, fabricators, and engineers usually want to know more than the name of the grade. They need to confirm the governing specification, plate condition, chemistry limits, mechanical properties, impact test requirements, thickness range, and any supplementary requirements tied to code construction. Those details determine whether a516 grade 70 is suitable for a vessel shell, head, heat exchanger component, separator, or storage application.
What Is A516 Grade 70?
A516 Grade 70 is a carbon-manganese-silicon steel plate specification intended primarily for welded pressure vessels where improved notch toughness is important. It belongs to the ASTM A516 / ASME SA516 family, which includes Grades 55, 60, 65, and 70. Grade 70 is the highest strength grade in the standard range and is therefore the most widely used where designers want a balance of strength, fabrication practicality, and broad code familiarity.
Unlike general-purpose structural plate, A516 Grade 70 is associated with pressure vessel documentation and traceability requirements. Material is commonly ordered with mill test reports, heat identification, and code-related verification because it is used in pressure-retaining service rather than ordinary structural fabrication.
ASTM A516 Grade 70 vs ASME SA516 Grade 70
The terms ASTM A516 Grade 70 and ASME SA516 Grade 70 are often used interchangeably in industry discussion, but the documentation context matters. ASTM A516 Grade 70 refers to the ASTM material specification. ASME SA516 Grade 70 is the corresponding ASME Boiler and Pressure Vessel Code material specification adopted for code construction.
For vessels built to ASME Section VIII or related code rules, the ASME designation is typically the controlling reference in project documentation. In many supply chains, plate may be supplied as dual-certified material where permitted, but purchasers should still verify the exact code edition and ordering requirements.
- Applicable specification and edition year
- Plate condition such as as-rolled or normalized
- Required impact testing and minimum design metal temperature
- Supplementary requirements such as ultrasonic examination
- Any restrictions on chemistry, carbon equivalent, or fine grain practice
- Traceability, stamping, and material test report requirements
A516 Grade 70 Chemical Composition
The chemical composition of A516 Grade 70 is controlled within specification limits and can vary by thickness and mill practice. It is fundamentally a carbon steel with manganese and silicon additions used to achieve the required strength and toughness characteristics. Exact values should always be confirmed against the governing specification and the mill test certificate for the supplied plate.
Typical maximum chemistry limits often referenced for A516 Grade 70 plate include carbon, manganese, phosphorus, sulfur, and silicon. Depending on thickness and production route, some limits may vary, and supplementary purchase requirements may further tighten chemistry for weldability or low-temperature performance.
| Property | A516 Grade 70 Typical Requirement | Notes |
|---|---|---|
| Specification | ASTM A516 / ASME SA516 | Pressure vessel quality carbon steel plate |
| Grade | 70 | Highest strength grade in the standard A516 range |
| Carbon | Varies by thickness, commonly up to about 0.27-0.31% max | Check current spec edition and thickness range |
| Manganese | Typically controlled range | Supports strength and toughness |
| Silicon | Typically specified minimum/maximum range | Used for deoxidation and strength contribution |
| Tensile Strength | 70-90 ksi | Approx. 485-620 MPa |
| Yield Strength | Minimum 38 ksi | Approx. 260 MPa |
| Elongation | Specified by thickness and gauge length | Verify against ordered thickness |
| Supply Condition | As-rolled or normalized | Depends on thickness and order requirements |
Mechanical Properties of A516 Grade 70
The reason A516 Grade 70 is so widely used is that its mechanical property profile is well suited to pressure vessel fabrication. It offers a minimum tensile strength of 70 ksi and a minimum yield strength of 38 ksi, giving designers more strength than lower A516 grades while maintaining practical forming and welding characteristics.
Elongation requirements depend on plate thickness and test specimen configuration. For engineering review, the key point is that the specification is designed around pressure vessel performance, not just nominal strength. Toughness, ductility, and consistency are important because the material is routinely used in shells, heads, nozzles, channel covers, and other welded components subject to pressure and thermal cycling.
Common Applications for A516 Grade 70 Plate
A516 Grade 70 is used across process industries wherever carbon steel pressure vessel plate is acceptable under the design code and service conditions. It is especially common in fabricated equipment that requires good weldability and dependable service performance at moderate temperatures.
Typical applications include:
- Pressure vessel shells and formed heads
- Boiler drums and boiler components
- Heat exchanger channel covers and shells
- Columns, separators, scrubbers, and receivers
- Storage tanks for process service
- Skid-mounted process modules
- Refinery and petrochemical fabricated components
- Water treatment and utility pressure equipment
Heat Treatment, Plate Condition, and Toughness
A516 Grade 70 may be supplied in different conditions depending on thickness, specification rules, and purchaser requirements. Common supply conditions include as-rolled and normalized. Normalizing is often specified when improved toughness, more uniform microstructure, or code/project requirements apply.
Notch toughness is one of the reasons this grade is preferred over more general carbon steel plate for pressure vessel service. However, toughness should never be assumed from the grade name alone. If the application has a defined minimum design metal temperature or impact test requirement, the purchase order should clearly state the required Charpy testing conditions, test temperature, and acceptance criteria.
For critical service, buyers may also request supplementary requirements such as ultrasonic testing, fine grain practice, or additional through-thickness performance depending on fabrication stresses and service severity.
Welding and Fabrication Considerations
A516 Grade 70 is generally regarded as a weldable carbon steel plate, which is one of the main reasons it is used so extensively in vessel shops. Standard fabrication operations such as cutting, rolling, forming, and welding are routinely performed on this grade. Nevertheless, welding procedures must still account for plate thickness, restraint, hydrogen control, joint design, and applicable code qualification requirements.
In production, fabricators commonly review the following before welding:
- Plate thickness and whether preheat is required
- Specified heat treatment condition
- Welding process and consumable selection
- Post weld heat treatment requirements from the design code
- Impact test obligations for weld procedure qualification
- Any purchaser limits on hardness or carbon equivalent
Because actual weldability can vary with chemistry and thickness, the mill test report and approved welding procedure specification should be reviewed together rather than relying only on a generic material description.
A516 Grade 70 Compared With Other Plate Grades
Within the A516 family, Grade 70 provides higher tensile strength than Grades 55, 60, and 65, which is why it is often selected as the default pressure vessel carbon steel plate. Compared with structural grades such as ASTM A36 or A572, A516 Grade 70 is more directly aligned with pressure vessel service and notch toughness expectations. Compared with higher-alloy or low-temperature steels, it is usually more economical and easier to source, but it may not be suitable where corrosion resistance, elevated temperature strength, or severe low-temperature toughness is required.
Selection should therefore be based on service conditions, code requirements, corrosion allowance, design temperature, and fabrication route rather than strength alone.
Procurement Checklist for A516 Grade 70
When ordering A516 Grade 70 plate, procurement documents should be specific enough to avoid substitution risk or code nonconformance. A complete order description usually includes the material designation, thickness, width, length, quantity, plate condition, testing requirements, and documentation requirements.
- Specify ASTM A516 Grade 70 or ASME SA516 Grade 70 as required
- State the applicable specification edition
- Confirm normalized or as-rolled condition
- Include impact testing requirements if applicable
- Request MTRs and traceability details
- Identify any supplementary requirements such as UT
- Confirm code construction and stamping expectations
FAQ
Is A516 Grade 70 the same as SA516 Grade 70?
They are closely related but not identical in documentation context. ASTM A516 Grade 70 is the ASTM specification, while ASME SA516 Grade 70 is the ASME-adopted specification used for code pressure vessel construction. The project code and purchase documents determine which designation governs.
What is A516 Grade 70 used for?
A516 Grade 70 is used for welded pressure vessels and related equipment such as shells, heads, heat exchangers, separators, boilers, and process plant components where good weldability, reliable strength, and notch toughness are required.
What are the key mechanical properties of A516 Grade 70?
A516 Grade 70 typically has a minimum tensile strength of 70 ksi, a tensile range of about 70-90 ksi, and a minimum yield strength of 38 ksi. Elongation and toughness requirements depend on thickness, specification edition, and any additional impact test requirements stated in the order.