SA-302 Grade A plate: keep the specified strength class intact
A requisition for SA302 Grade A calls for a particular manganese–molybdenum pressure-vessel plate, not simply the lowest price within an alloy-steel family. Gangsteel welcomes enquiries that preserve the designer’s Grade A selection and define the acceptance documents before material is proposed. Lower specified strength than neighbouring grades does not make Grade A a general substitute for carbon plate or an invitation to change the ordered grade.
Start with the material line on the approved requisition
For ASME work, identify SA-302 or SA-302M, Grade A, and the governing Code year or Section II-A edition. Include the unit system, dimensions, quantity, delivery condition, required tests and certificate form. A generic “SA302 alloy plate” enquiry leaves both grade identity and acceptance unresolved. If different documents disagree, obtain a coordinated material instruction rather than choosing whichever description suits an available offer.
| Purchase decision | Specify before offer approval | Verify before material release |
|---|---|---|
| ASME identity | SA-302 or SA-302M; Grade A; Code year or Section II-A edition | Exact designation and governing edition in the accepted documentation |
| Plate schedule | Unit system, thickness, width, length, quantity and tolerances | Piece identity and dimensions linked to the order |
| Condition and examination | Required delivery condition and tests with acceptance criteria | Reported treatment and completed examination scope |
| Certificate form | Report format, traceability and any witness requirements | Heat and plate identifiers, actual results and required endorsements |
An ASTM A302 Grade A certificate is not by itself SA-302 acceptance; the reverse is not automatic either. Dual certification needs an agreed and documented compliance basis. Historical ASME contents evidence confirms the SA-302/SA-302M title only, not a current adoption year. BPVC.II.A-2025 has not been read for this summary. The family guidance below is not an official SA-302 extract for a named Code year.
Recognize Grade A without borrowing Grade B strength
Official ASTM A302/A302M-17(2022) public Scope identifies Grade A as manganese–molybdenum plate for welded boilers and other pressure vessels. Its tensile range is the lower family range shown below. Nickel is not specified for Grade A in the checked public references; the nickel-bearing family members are C and D. “Not specified” is not a statement that a particular heat contains absolutely no nickel.
| Characteristic | Reference value | Evidence boundary |
|---|---|---|
| Tensile strength | 75–95 ksi [515–655 MPa] | Official ASTM public Scope, used here as family information |
| Yield strength, minimum | 45 ksi [310 MPa] | Ferrobend Grade A and dated trader compilation |
| Elongation, 8 in. [200 mm] gauge | 15% | Public reference; applicable specimen adjustments |
| Elongation, 2 in. [50 mm] gauge | 19% | Public reference; not the Grade B short-gauge value |
The 310 MPa yield figure is correct for Grade A’s public-reference level. It must not be replaced merely because a higher figure appears on another family page. Likewise, the short-gauge elongation is 19%, not Grade B’s value. A certificate review should check the actual tensile range, yield result and applicable elongation together; a single satisfactory yield result cannot establish complete compliance.
Elongation depends on the specified gauge and specimen rules, not a choice between two thickness bands. Establish which specimen represents the ordered material and apply only the adjustments permitted by the governing requirements. Room-temperature test properties are not allowable stresses at operating temperature. Service suitability, design stress and any toughness assessment remain engineering and construction-code decisions.
Review the lower Grade A manganese band separately
These mass percentages are public-reference chemistry, not an official paid Table 1. The September 2026 SHH/SteelSpecs trader compilation supplies the heat/product split. Ferrobend’s Grade A table corroborates the product-style manganese, silicon and molybdenum bands; its compressed cells must not be treated as heat analysis. Its carbon note applies to both heat and product analyses.
| Element and thickness basis | Heat analysis | Product analysis |
|---|---|---|
| Carbon, ≤1 in. [25 mm], max | 0.20 | 0.20 |
| Carbon, >1–2 in. [>25–50 mm], max | 0.23 | 0.23 |
| Carbon, >2 in. [>50 mm], max | 0.25 | 0.25 |
| Manganese | 0.95–1.30 | 0.87–1.41 |
| Silicon | 0.15–0.40 | 0.13–0.45 |
| Molybdenum | 0.45–0.60 | 0.41–0.64 |
| Phosphorus, max | 0.025 | |
| Sulfur, max | 0.025 | |
| Nickel |
Grade A’s manganese is 0.95–1.30% heat and 0.87–1.41% product. Keep those ranges distinct from the higher B/C band and from a single maximum-only heading. Phosphorus and sulfur have 0.025% heat-reference maxima. Their product-analysis cells remain blank because a separate product limit was not established here. Nickel’s blank numerical cells mean no specified Grade A band was established, not a guessed zero or a copied C-grade limit.
Use certified heat chemistry when discussing fabrication with the responsible specialist. A catalogue maximum is neither an actual composition nor a welding procedure. Any project restriction on residuals or chemistry calculations should state the analysis basis and acceptance criterion. Do not complete a missing report entry by substituting the reference-table limit.
Order condition, thickness and supplementary evidence together
Official ASTM public Scope makes maximum thickness composition-limited: the chemistry must be capable of meeting the mechanical requirements. It gives no fixed numerical thickness cap. A mill’s advertised rolling range is a separate capability statement, so feasibility must be confirmed for the requested size, condition and testing arrangement rather than assumed from the specification name.
As a labelled ASTM-family compilation restatement, the dated trader source describes plate 2 in. [50 mm] and under as normally as-rolled, with normalizing or stress relieving when ordered, and plate over that threshold as normalized. Official public Scope is silent on heat treatment, and the paid SA-302 clause was not read. Confirm this delivery pattern against the named Code edition; no treatment temperature or quench-and-temper default is asserted.
Inch-pound and SI values are separately standard and not exact mathematical equivalents. Select one controlling unit system and use it independently. The official ASTM abstract describes killed steel, fine-grain requirements and tension testing across the family, not just Grade C. Compilation references to A20/A20M or SA-20 for common requirements need confirmation in the ordered ASME basis rather than being presented as wording from public Scope.
Specify any required impact testing, ultrasonic examination or fabrication-cycle simulation explicitly. Include the method, acceptance criteria and representative condition. There is no default impact energy, temperature or UT coverage promised here. Welding controls should be established for the actual material and joint, while plate identification should remain linked to reports through any agreed cutting operation.
Related family pages for navigation
See ASME SA302 Grade C plate for the nickel-bearing related topic, or ASME SA302 Grade B plate for the neighbouring Mn–Mo topic. These links are not technical sources for Grade A numbers and do not authorize a change of material. A proposed alternative must return to the project’s approval process.
Grade A procurement questions
Is SA302 Grade A a nickel-alloy grade?
The official ASTM family Scope identifies A as manganese–molybdenum. Checked public compilations leave nickel unspecified. If residual nickel matters to the project, request the actual heat result and a defined restriction rather than assuming zero.
Should 310 MPa yield be corrected to a higher family value?
No. Grade A’s public-reference minimum is 45 ksi [310 MPa]. Keep the grade-specific strength and elongation requirements together, and verify them against the governing ASME edition before acceptance.
Can Grade B be supplied as an automatic upgrade?
No. Higher nominal strength does not establish compliance with a Grade A requisition. Chemistry, condition, fabrication requirements, design acceptance and documents require review before a grade change is approved.
What must be clear about the delivery condition?
State the required condition on the order and compare it with the report. The 2 in. [50 mm] pattern is only a labelled family compilation here; resolve the named SA requirements rather than relying on a commercial heading.
Does ordering a certificate automatically add UT or impact tests?
No. Specify examinations and acceptance criteria where required, including specimen conditions for impact testing. A material report must document the agreed scope; its existence alone does not add unspecified tests.
Submit a Grade A material schedule
Send the SA designation, governing Code edition, unit system, plate dimensions and quantity, delivery condition, tests and certificate form. Include project-specific restrictions so Gangsteel can review the enquiry without assuming a grade change or a default inspection package.