ASTM A516 Grade 70 Boiler Plate
If there is one boiler and pressure vessel plate that dominates global procurement lists, it is ASTM A516 Grade 70. Across refineries, gas processing plants, power stations, and chemical facilities on every continent, Gr. 70 has become the default specification for boiler shells, pressure vessel shells, heads, and nozzle pads — and for good reason.
A516 Grade 70 is the highest-strength grade within the A516 pressure vessel and boiler plate family. It delivers a tensile range of 485–620 MPa and a minimum yield strength of 260 MPa, providing the combination of pressure-bearing capacity and material toughness that most boiler and vessel design codes are built around.
Critically, A516 Gr. 70 is not just a strong plate — it is a tough one. Produced to fine-grain practice with controlled silicon content, it maintains reliable notch toughness at temperatures well below ambient, making it suitable for a wide range of boiler and pressure applications. This is why ASME SA-516 Grade 70 is widely referenced in ASME Section I (boilers) and Section VIII Div. 1 (pressure vessels) as the go-to carbon steel material.
Mechanical Properties
| Property | Value | Unit |
|---|---|---|
| Tensile Strength | 485 – 620 | MPa |
| Yield Strength (min.) | 260 | MPa |
| Elongation in 200 mm (min.) | 17 | % |
| Elongation in 50 mm (min.) | 21 | % |
| Brinell Hardness | 137 – 187 | HB |
| Density | 7.85 | g/cm³ |
| Modulus of Elasticity | 200 | GPa |
Chemical Composition
| Element | Max. Content (%) |
|---|---|
| Carbon (C) | 0.24 (t ≤ 13 mm) / 0.27 (13–51 mm) / 0.28 (51–102 mm) / 0.31 (> 102 mm) |
| Manganese (Mn) | 0.85 – 1.20 |
| Phosphorus (P) | 0.035 |
| Sulfur (S) | 0.035 |
| Silicon (Si) | 0.13 – 0.45 |
Applications
A516 Gr. 70 is the industry-standard specification for boiler plates and pressure-containing equipment:
- Boiler Shells & Drums — Primary material for steam boiler shells, steam drums, and water tube boiler components under ASME Section I.
- Pressure Vessel Shells & Heads — Cylindrical shells, hemispherical and ellipsoidal heads, and conical transitions.
- High-Pressure Storage Tanks — LPG, compressed air, and industrial gas storage vessels.
- Heat Exchangers — Shell plates, channel covers, and floating head components.
- Reactor Vessels — Used in chemical processing, fertilizer plants, and refineries.
- Offshore Boiler & Pressure Systems — Equipment requiring strict traceability and ASME compliance.
Weldability & Processing
- Weldability: A516 Gr. 70 boiler plate welds reliably using standard arc welding processes. Its controlled chemistry and fine-grain structure maintain a moderate carbon equivalent, minimizing hardening in the heat-affected zone.
Up to 19 mm: No preheat typically required
19–38 mm: 80–100 °C preheat
Above 38 mm: 100–150 °C preheat - Post-Weld Heat Treatment (PWHT): PWHT is commonly applied in boiler fabrication to relieve residual stresses, especially for:
Thick plates (>38 mm)
Hydrogen or sour service
High-pressure boiler applications - Normalizing: Normalized A516 Gr. 70 (Gr. 70N) improves Charpy impact toughness and is preferred for:
Low-temperature boiler service
Critical pressure applications - Cold Forming: Widely used for forming boiler shells, dished ends, and heads. Post-forming heat treatment may be required as per ASME guidelines.
A516 Grade 60 vs Grade 70 — Key Differences
| Property | Value 1 | Value 2 |
|---|---|---|
| Tensile Strength | 415 – 550 MPa | 485 – 620 MPa |
| Yield Strength (min.) | 220 MPa | 260 MPa |
| Carbon Content (max.) | Lower | Higher |
| Low-Temp. Toughness | Slightly better | Good (fine grain) |
| Best Use Case | Moderate pressure | High-pressure boilers |
| Wall Thickness | Thicker | Thinner |
Manufacturing Standards & Equivalents
- ASTM A516
- ASME Equivalent: SA-516 Grade 70
Quality Assurance
- Mechanical Testing: Each plate is tested for tensile strength (485–620 MPa), yield strength (min. 260 MPa), and elongation per ASTM A370. Charpy impact testing is conducted when specified.
- Dimensional Accuracy: Plates conform to ASTM A20 tolerances for thickness, flatness, width, and length.
- Weldability Tests: Weld procedures are qualified as per ASME Section IX, ensuring strength and ductility across weld joints.
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- Oil & Gas industries
- Chemical process industries
- Pump and valve in high pressure component
- Food industries
- Pulp and paper industry
- Aerospace industry
- Power plant
- Mechanical component
- Sugar industry
- Cement industry