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ASTM A533 Grade A Class 3 steel plate, also written as ASME SA533 Grade A Class 3, A533 Type A Class 3, A533 Gr.A Cl.3 steel plate, SA533 Grade A Class 3 plate, is a Mn-Mo quenched-and-tempered alloy steel plate under ASTM A533/A533M (ASME SA533/SA533M) for welded pressure vessels. Type/Grade A is Mn-Mo without specified nickel. Class 3 provides 83 ksi [570 MPa] min yield and 100-125 ksi [690-860 MPa] tensile strength with 16% min elongation in 50 mm. Gangsteel (HENAN GANG IRON AND STEEL) produces and exports A533/SA533 Grade A Class 3 plates cut to size with MTC for heavy vessels, boiler drums and nuclear-adjacent projects when ordered.
Data source: Per ASTM A533/A533M / ASME SA533/SA533M (Pressure Vessel Plates, Alloy Steel, Quenched and Tempered, Manganese-Molybdenum and Manganese-Molybdenum-Nickel). ASTM designates Types A–E; commercial purchase orders commonly say Grade A. This page set covers all Types/Grades A/B/C/D/E × Classes 1/2/3 per ASTM A533/A533M-24. Official mill/certificate designation is A533 Type/Grade A Class 3 (or SA533 when ASME stamped/ordered). Verify the contracted edition and purchase-order supplements before ordering.
| Element | C | Mn | P | S | Si | Mo |
|---|---|---|---|---|---|---|
| A533 Gr.A, % | 0.25 max | 1.15-1.50 | 0.025 max | 0.025 max | 0.15-0.40 | 0.45-0.60 |
| Element | Ni | Cu | V | Cr | — | — |
|---|---|---|---|---|---|---|
| A533 Gr.A, % | — | — | — | — | — | — |
Heat analysis per ASTM A533/A533M Type/Grade A. Product analysis tolerances per A533/A20. Mn max may be raised for Class 2/3 under Supplementary Requirement S3 when specified. Verify the contracted edition before ordering.
This page: Grade A Class 3 — yield 83 ksi [570 MPa], tensile 100-125 ksi [690-860 MPa], elongation 16% min.
| Class | Yield min | Tensile | Elongation (in 50 mm), min |
|---|---|---|---|
| Class 1 | 50 ksi [345 MPa] | 80-100 ksi [550-690 MPa] | 18% |
| Class 2 | 70 ksi [485 MPa] | 90-115 ksi [620-795 MPa] | 16% |
| Class 3 | 83 ksi [570 MPa] | 100-125 ksi [690-860 MPa] | 16% |
Strength classes apply across Grades/Types A–D. This page focuses on Grade A Class 3 (83 ksi min yield, 100–125 ksi tensile). Impact / UT / NDT follow the purchase order and ASME Section / project nuclear requirements when specified.
Quenched and tempered (QT). Tension tests per ASTM A533; Charpy impact and ultrasonic examination per purchase order / ASME Section requirements when specified. EN 10204 3.1 as standard; 3.2 or ASME-related documentation as ordered. Plates are normally shipped QT; as-rolled shipment only by mutual agreement.
Minimum nominal thickness 0.25 in. [6.5 mm]. Class 1 and Class 2 practice typically up to about 12 in. [300 mm] for Types/Grades A–D; Class 3 max about 2.5 in. [65 mm]. Gangsteel supplies cut-to-size within mill QT capability—confirm thickness on the PO.
Welded pressure vessels, boiler drums, reactor and nuclear-adjacent beltline components, and high-integrity heavy vessels specifying A533/SA533 Mn-Mo or Mn-Mo-Ni QT plate. Grade A Class 3 is selected for the required alloy (Ni) band and strength class.
| Standard | Comparable grade (approximate) |
|---|---|
| ASTM | A533 Grade A Class 3 |
| ASME | SA533 Grade A Class 3 |
| Related QT / alloy | ASTM A537 / SA302 / A302 / A543 (Ni-Cr-Mo, related) |
| Low-temp Ni (different family) | ASTM A553 Type I / GB/T 3531 |
| Other A533 pages | Grade A Class 1 | Grade A Class 2 | Grade B Class 1 | Grade B Class 2 | Grade B Class 3 | Grade C Class 1 |
Equivalents are engineering references only. Dual certification requires the stricter combined limits on the PO and MTC.
It is a Mn-Mo quenched-and-tempered pressure vessel plate under ASTM A533/A533M (ASME SA533/SA533M). a Mn-Mo quenched-and-tempered alloy steel plate under ASTM A533/A533M (ASME SA533/SA533M) for welded pressure vessels. Type/Grade A is Mn-Mo without specified nickel. Class 3 provides 83 ksi [570 MPa] min yield and 100-125 ksi [690-860 MPa] tensile strength with 16% min elongation in 50 mm. ASTM designates Types A–E; commercial orders often say Grade A. See the full ASTM A533 Grade A Class 3 page for chemistry and mechanical tables.
For Class 3: minimum yield 83 ksi [570 MPa]; tensile 100-125 ksi [690-860 MPa]; elongation min 16% in 50 mm. Strength is set by Class (1/2/3); alloy band is set by Type/Grade (A/B/C/D).
Grades/Types share the same Mn-Mo base chemistry and Class strength tables. They differ mainly by nickel: A has no specified Ni; B 0.40–0.70%; C 0.70–1.00%; D 0.20–0.40%; E 0.60–1.00% with Cr 0.60 max, C 0.20 max and lower Mo 0.25–0.60% (heat analysis). This page is Grade A Class 3. Hub: ASTM A533 Steel Plate.
Class is the strength level after quench and temper: Class 1 (50 ksi yield / 80–100 ksi tensile), Class 2 (70 / 90–115), Class 3 (83 / 100–125). This page is Class 3.
Quenched and tempered (QT). Tension tests per ASTM A533; Charpy impact and ultrasonic examination per purchase order / ASME Section requirements when specified. EN 10204 3.1 as standard; 3.2 or ASME-related documentation as ordered. Plates are normally shipped QT; as-rolled shipment only by mutual agreement.
Same Grade A other classes: Grade A Class 1 / Grade A Class 2. Same Class 3 other grades: Grade B Class 3 / Grade C Class 3 / Grade D Class 3 / Grade E Class 3. Hub: ASTM A533 / SA533.
ASME SA533 is the ASME Boiler and Pressure Vessel Code twin of ASTM A533. Chemistry and Class tables align; order the book required for code stamping. Dual ASTM/ASME marking needs the stricter combined limits on the PO and MTC.
A533 is Mn-Mo / Mn-Mo-Ni quenched and tempered alloy plate. ASTM A537 is heat-treated C-Mn vessel plate (Classes 1/2/3). ASME SA302 / A302 is related Mn-Mo (and Ni) alloy plate often compared for drums. They are not drop-in equivalents; compare chemistry, heat treatment and impact rules before dual certification.
EN 10204 3.1 as standard; 3.2 with third-party inspection when ordered. MTC lists heat analysis, mechanical tests, QT delivery condition and any optional UT / impact / project nuclear results.
Minimum nominal thickness 0.25 in. [6.5 mm]. Class 1 and Class 2 practice typically up to about 12 in. [300 mm] for Types/Grades A–D; Class 3 max about 2.5 in. [65 mm]. Gangsteel supplies cut-to-size within mill QT capability—confirm thickness on the PO. Browse the ASTM A533 hub for the full Grade×Class list.
ASTM A533 / SA533 Hub | A533 Grade B Class 1 | A533 Grade A Class 1 | ASTM A537 | ASME SA302 | ASTM A516 | GB/T 713 | Pressure Vessel Steel Plate | Boiler Steel Plate
