Where ASME SA283 Sits in the Standard System
ASME SA283 is issued in the ASME Boiler and Pressure Vessel Code, Section II, Part A, and is technically identical to ASTM A283/A283M. Using the SA prefix instead of the A prefix signals that the material is being purchased to the ASME code edition for pressure-retaining or code-stamped construction, while the mechanical and chemical requirements remain those of the ASTM specification.
The specification covers four grades, A, B, C and D, each offered in the as-rolled or normalized condition for plate. Strength increases from grade to grade without changing the basic family: all four are plain carbon steels with a maximum manganese content of about 0.90%, no deliberate alloying additions and no minimum alloy content, which keeps them inexpensive, predictable to weld and easy to form.
Grades and Mechanical Properties
| Grade | Tensile strength, ksi | Tensile strength, MPa | Yield point min, ksi | Yield point min, MPa | Elongation min, % |
|---|---|---|---|---|---|
| A | 45-60 | 310-415 | 24 | 165 | 27 |
| B | 50-65 | 345-450 | 27 | 185 | 25 |
| C | 55-75 | 380-515 | 30 | 205 | 22 |
| D | 60-80 | 415-550 | 33 | 230 | 20 |
The elongation minima shown are for the standard rectangular tension test piece; the specification allows slightly lower values for small-size specimens, and the actual figure is recorded on the inspection certificate. Because the strength ladder is created by carbon and manganese rather than by alloying, the higher grades are progressively less ductile, which is why Grade A is preferred for severe forming and Grade D for plate that mainly has to carry load.
Chemical Composition Limits
| Element, max % | Grade A | Grade B | Grade C | Grade D |
|---|---|---|---|---|
| C | 0.14 | 0.17 | 0.24 | 0.27 |
| Mn | 0.90 | 0.90 | 0.90 | 0.90 |
| P | 0.035 | 0.035 | 0.035 | 0.035 |
| S | 0.040 | 0.040 | 0.040 | 0.040 |
| Si | 0.40 | 0.40 | 0.40 | 0.40 |
These limits apply to plate up to 40 mm; heavier plate is governed by the thickness-dependent provisions of the specification. Silicon is normally held at 0.15-0.40% as a deoxidation residue, and the steel is fully killed for plate thicknesses where the specification requires it. Sulphur and phosphorus are not tightly restricted by this specification, so the buyer who needs improved through-thickness ductility or low-temperature toughness should move to a fine-grain or low-sulphur specification rather than expect SA283 to deliver it.
Applications and Grade Selection
Grade A and Grade B are used for low-pressure storage tanks, water and air receivers, bins, hoppers, ductwork, chutes and non-critical welded frames. Grade C and Grade D appear in heavier industrial structures, machine bases, bridge bearing plates, transition pieces and low-pressure vessel components where the design stress is higher but the temperature stays well above freezing.
Where the application must be compared with other systems, the natural references are ASTM A36 for general structural plate, EN 10025-2 S235JR with a 235 MPa yield and 360-510 MPa tensile range, JIS G3101 SS400 with a 245 MPa yield and 400-510 MPa tensile range, and GB/T 700 Q235B with a 235 MPa yield and 370-500 MPa tensile range. Those grades are similar in strength class to SA283 Grade B, but they are separate specifications; equivalence must be confirmed on chemistry, impact requirement and code acceptance rather than by name.
Supply Range, Delivery Condition and Quality Control
SA283 plate is normally supplied as-rolled in thicknesses from 6 mm to 150 mm, with normalized plate available where a more uniform structure is needed. Cutting is by plasma, laser, waterjet or flame, and the low carbon content means no preheat is needed for welding at ordinary thicknesses with any conventional process. Cold forming of Grade A is straightforward; Grades C and D should be formed with larger radii and, for cold work above about 5% strain, a stress-relief treatment may be appropriate.
Documentation follows EN 10204 with a 3.1 inspection certificate carrying heat analysis, product analysis, tensile results and, when ordered, impact results. Because grade identification matters more than appearance, plate marking should carry the SA or A designation, the grade letter, the heat number and the mill identification. Buyers who need impact energy guarantees at a specific temperature, tighter sulphur control, ultrasonic examination to EN 10160 or thickness-direction properties should specify those requirements as additions, since the base specification does not provide them.
Regular stock programmes usually hold Grade A, B and C in the common thicknesses from 6 mm to 50 mm, while Grade D and heavy plate are produced against order because the higher carbon content requires closer control of rolling and cooling.
Frequently Asked Questions
Q: Is ASME SA283 the same as ASTM A283?
A: Yes. SA283 is the ASME code edition of ASTM A283/A283M, with identical chemistry and mechanical requirements.
Q: What is the difference between SA283 Grade C and Grade D?
A: Grade D has higher tensile and yield minima than Grade C, 60-80 ksi and 33 ksi against 55-75 ksi and 30 ksi, and a lower elongation requirement.
Q: Can SA283 plate be welded without preheat?
A: For ordinary thicknesses and ambient conditions, yes. The carbon content is low, and normal low-hydrogen practice is adequate without preheat.
Q: Does SA283 have a guaranteed impact toughness?
A: No. Impact testing is not a base requirement, so a low-temperature application needs a different specification or a supplementary impact requirement agreed at order.
Q: What thickness is available in SA283?
A: Production normally covers 6 mm to 150 mm, with 6 mm to 50 mm held in stock for the common grades.
Q: Which SA283 grade is closest to S235JR?
A: Grade B is the usual comparison, since its 345-450 MPa tensile range and 185 MPa yield sit close to the S235JR strength class, but the specifications remain separate.
