SA-283 Grade C: Material Profile
SA-283 Grade C is the ASME Boiler and Pressure Vessel Code designation for ASTM A283 Grade C, a low-to-intermediate tensile strength carbon steel plate used primarily for general construction and pressure components where excellent formability and weldability are prioritized over high strength.
Quick-Reference Specification OF ASTM A283 Grade C
| Category | Specification |
|---|---|
| Standard | ASTM A283 / ASME SA-283 |
| Type | Carbon Steel (Plain Carbon, Non-Alloy) |
| Condition | Typically supplied as hot-rolled. |
| Key Feature | Guaranteed minimum manganese for predictable fabrication. |
| Primary Domain | Low-pressure vessels, tanks, and formed structural components. |
1. Chemical Composition (Weight %)
Its chemistry is defined for consistency and weldability.
| Element | Requirement (Grade C) | Purpose / Effect |
|---|---|---|
| Carbon (C) | ≤ 0.24% | Controlled for weldability and formability. |
| Manganese (Mn) | ≥ 0.90% (up to 0.50% for rimmed) | Key differentiator. Minimum ensures strength, grain refinement, and good toughness. |
| Phosphorus (P) | ≤ 0.04% | Impurity control. |
| Sulfur (S) | ≤ 0.05% | Impurity control. |
| Deoxidation | Semi-killed or killed (for plates > 0.5 in.) | Ensures internal soundness for welding and forming. |
Note: The mandatory minimum manganese (0.90%) is the critical feature that distinguishes it from steels like A36, which have no minimum Mn requirement.
2. Mechanical Properties
| Property | Requirement (for plates) |
|---|---|
| Yield Strength (min) | 30 ksi (205 MPa) |
| Tensile Strength (min) | 55 ksi (380 MPa) |
| Elongation (min, in 2") | 25% (higher than many structural steels) |
| Impact Toughness | Not required by default. |
3. Key Advantages & Characteristics
Excellent Formability: High ductility makes it ideal for cold bending, rolling, and punching.
Predictable Weldability: Controlled chemistry and semi-killed/killed practice result in reliable, crack-resistant welds.
Good Internal Soundness: Reduced porosity and segregation compared to rimmed steels.
Cost-Effective Fabrication: Often lower material cost than high-strength steels, and its fabricability reduces labor costs.
4. Primary Applications
SA-283 Grade C is a "fabricator's steel," not a high-strength structural steel.
Pressure Vessels & Tanks:
Water Storage Tanks, Air Receivers, Oil Storage Tanks (for low-to-moderate pressure).
Code Stamp: Used for ASME Section VIII, Div. 1 UM stamped vessels.
General Construction & Fabrication:
Ductwork, Hoppers, Chutes, and Bins.
Architectural Panels and Cladding (where complex forming is needed).
Stair Treads, Floor Plate, and Walkways.
Miscellaneous Components:
Baseplates, Shims, and Mounting Brackets.
Agricultural Equipment parts.
5. Fabrication Considerations
| Process | Guidelines |
|---|---|
| Welding | Excellent weldability. All standard processes (SMAW, GMAW, FCAW) work well. No pre-heat required for typical thicknesses. Use E60XX or E70XX filler. |
| Forming | Ideal for cold forming. Can be bent to tight radii without cracking. |
| Cutting | All thermal and mechanical methods (plasma, oxy-fuel, shear) apply easily. |
| Machining | Good machinability with standard tools. |
6. Comparison with Key Grades
| Grade | Key Difference from SA-283 Gr. C |
|---|---|
| ASTM A36 | Higher strength (36 ksi yield vs. 30 ksi). A36 is performance-based; SA-283 Gr. C has guaranteed chemistry (min. Mn) for fabricability. |
| ASTM A516 Gr. 55/60 | Pressure vessel steel with higher strength, normalized grain structure, and mandatory impact testing for low-temperature service. |
| ASTM A572 Gr. 50 | Much higher strength (50 ksi yield). HSLA, microalloyed steel for structural weight savings. |
7. Important Limitations
Not for Primary Structures: Its 30 ksi yield strength is low. It is not suitable for beams, columns, or trusses in major buildings or bridges without significant over-design.
No Toughness Guarantee: Avoid in low-temperature or impact-load applications unless supplementary Charpy testing is specified.
Lower Strength: Requires thicker sections to carry the same load as A36 or A572, which can offset material cost savings.
Summary
SA-283 Grade C is a reliable, ductile, and weldable carbon steel for fabricated components where forming and joining are the main challenges, not structural efficiency. Its niche is in tanks, non-critical formed parts, and general fabrication where its excellent shop workability leads to cost-effective and reliable end products. It is the wrong choice for high-strength structural framing but an excellent choice for the "containers and skins" of industrial and construction projects.
What is SA 283 Grade C equivalent to?
ASME SA 283 Gr C equivalent material in EN standard is S235JR steel. S235JR steel has good plasticity, toughness and weldability, certain strength and good cold bending properties.
What is ASTM A283 grade C?
ASTM A283 Grade C is a specification for low and intermediate tensile strength carbon steel plates of structual quality for general applications. ASTM A283 Grade C has a specified minimum yield strengths of 30 ksi.
What is the difference between A283 C and A36 C?
A36 has a lower carbon content compared to A283 Grade C, making it easier to weld and more ductile. Mechanical Properties: A283 Grade C: higher strength and higher yield point compared to A36, making it suitable for high-strength applications.
What is the allowable stress for A283 Grade C?
Most carbon grades, including the Sa 283 Gr C, have a maximum allowed stress of 13,750psi.
What is the difference between SA 283 C and SA 36?
Alloy Composition
These differences suggest that A36 might be preferred for applications requiring higher strength and better fatigue resistance, while SA283 Grade C could be suitable for applications where the slightly lower strength properties are acceptable and potentially more cost-effective.
Full specification and details are available on request. The above information is provided for guidance purposes only. For specific design requirements please contact our technical sales staff.
