SA-302 Grade C: make nickel and test evidence explicit
For SA302 Grade C, the buying decision cannot stop at a tensile range shared with another grade. This is a manganese–molybdenum–nickel pressure-vessel plate, and the specified nickel band, specimen basis and ASME acceptance record must remain visible through enquiry and document review. Gangsteel welcomes Grade C requirements with an approved material schedule and clearly defined delivery conditions.
Nickel is a defined part of the Grade C identity
The official ASTM A302/A302M-17(2022) public Scope identifies Grade C as manganese–molybdenum–nickel, at 80–100 ksi [550–690 MPa] tensile strength. On this ASME page that is family reference information, not an official SA-302 extract for a named Code year. Grade B shares the tensile class but has no specified nickel band; Grade D is another nickel-bearing grade with a higher public-reference nickel band, not an interchangeable name for C.
Check the analysis type before comparing a nickel result. The September 2026 SHH/SteelSpecs Grade C trader compilation separates heat and product analysis. Ferrobend’s Grade C page prints compressed product-style ranges, including nickel, rather than a heat-analysis table. The following chemistry is public reference, not paid official Table 1; acceptance must be resolved against the ordered SA edition.
| 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 | 1.15–1.50 | 1.07–1.62 |
| Silicon | 0.15–0.40 | 0.13–0.45 |
| Molybdenum | 0.45–0.60 | 0.41–0.64 |
| Nickel | 0.40–0.70 | 0.37–0.73 |
| Phosphorus, max | 0.025 | |
| Sulfur, max | 0.025 |
Nickel’s reference bands are 0.40–0.70% heat and 0.37–0.73% product. Those values come from independently checked columns, not correction by guesswork. A product-style upper limit cannot simply replace the heat upper limit. The same distinction applies to manganese, silicon and molybdenum. Carbon’s thickness bands apply to both analyses in Ferrobend’s note. Product phosphorus and sulfur limits were not separately established here and their numerical cells remain blank.
A plate with an acceptable nickel result still needs the rest of its chemistry and all required tests reviewed. Do not infer a complete material identity from one alloying element. If the project has residual-element restrictions, ask for actual heat data and define the acceptance basis rather than treating a generic family analysis as a particular melt’s certificate.
Keep Grade C elongation distinct even when strengths match
| Requirement | Reference value | How to use it |
|---|---|---|
| Tensile strength | 80–100 ksi [550–690 MPa] | Official ASTM public Scope; family information for this SA enquiry |
| Yield strength, minimum | 50 ksi [345 MPa] | Public reference from Grade C compilation columns |
| Elongation in 8 in. [200 mm] | 17% | Public minimum reference; verify specimen applicability |
| Elongation in 2 in. [50 mm] | 20% | Public minimum reference; verify permitted adjustments |
The elongation references are 17% and 20%, not Grade B’s pair. They are tied to gauge length, not plate-thickness ranges. Compare the actual specimen and any applicable adjustment before judging a report. Both lower and upper tensile limits matter, and satisfying one mechanical value does not cancel an unresolved chemistry, condition or documentation requirement.
Nickel content alone does not demonstrate a specified impact energy or a permitted minimum design metal temperature. The responsible engineer must evaluate toughness under the governing construction rules. Where impact testing is required, define temperature, orientation, specimen size, frequency and acceptance criteria; no numerical impact default or service-temperature guarantee is supplied by this summary.
Build the ASME acceptance basis into the enquiry
Name SA-302 or SA-302M, Grade C, and the governing Code year or Section II-A edition. An ASTM A302 Grade C certificate is not by itself SA-302 acceptance, nor is reverse acceptance automatic. Dual certification is a separate documented requirement, not a result created by overlapping strength figures. Certificate form and witnessing should be agreed in contract review rather than assumed from a supplier page.
| Item | Purchaser input | Review question |
|---|---|---|
| Code material identity | SA-302 or SA-302M, Grade C; Code year or Section II-A edition | Does the proposed documentation meet the named acceptance basis? |
| Geometry and units | Thickness, width, length, quantity, unit system and tolerances | Are sizes and controlling units consistent throughout? |
| Delivery condition | Required mill condition and relevant later thermal processing | Do test results represent the approved condition? |
| Tests and certificate form | Required tests, criteria, report format and witnessing | Are actual results and heat/plate identifiers linked correctly? |
A historical official ASME contents listing confirms the SA-302/SA-302M title only; it is not a current adoption table. BPVC.II.A-2025 has not been read for this summary, so no verified current Code year or adopted ASTM revision is assigned. Resolve the project’s required edition before an offer is accepted, particularly where a drawing and a requisition use different material descriptions.
Distinguish delivery practice from an unverified processing route
The dated trader compilation restates ordinary family delivery as normally as-rolled at 2 in. [50 mm] and under, with normalizing or stress relieving available when ordered, and normalized above that threshold. This is a labelled compilation restatement, not a verified paid SA-302 clause. Official public Scope is silent on heat treatment. Confirm the required condition against the named Code basis; no quench-and-temper default, temperature or cooling schedule is offered here.
The official ASTM abstract’s killed-steel, fine-grain and tension-test statements apply across the family, not exclusively to Grade C. Naming A20/A20M or SA-20 as the common-requirements document follows compilations and needs edition-specific confirmation; it is not a quotation from public Scope. A delivery-condition statement also does not by itself establish how later forming or fabrication heat treatment will affect the represented properties.
Maximum thickness in official ASTM public Scope is limited by composition’s ability to meet the mechanical requirements, not a fixed numerical cap. A commercial size range cannot be used as an ASME limit or a promise of availability. Keep inch-pound and SI requirements independent: they are separately standard and not exact mathematical equivalents. Use the selected system consistently for dimensions and compliance checks.
Where additional ultrasonic examination or testing after simulated fabrication treatment is required, state the method, acceptance level, coverage and representative condition in advance. Report review should connect each result to the relevant heat and plate. Qualified fabrication procedures must address the actual alloy and joint; a satisfactory plate tensile result is not a welding procedure or a universal toughness exemption.
Navigate related grades without approving substitutions
The ASME SA302 Grade A page and ASME SA302 Grade B page are related topics only, not sources for this page’s numerical requirements. Grade A has a different strength class, while Grade B lacks the specified nickel requirement. Neither is automatically acceptable in place of the designer’s Grade C selection.
Grade C buyer FAQs
Which nickel limits should be compared with a heat report?
The public-reference heat band is 0.40–0.70%. The 0.37–0.73% band is product analysis. Retain the analysis label and confirm the governing SA requirements before using either as an acceptance limit.
Why does matching Grade B tensile strength not make the grades equivalent?
The alloy identity and elongation references differ. Grade C specifies nickel and has 17% in 8 in. [200 mm] or 20% in 2 in. [50 mm] as public-reference elongations. Material selection and Code acceptance require more than matching tensile ranges.
Is Grade D another name for Grade C?
No. Public compilations give D a higher nickel band. It is a distinct grade and cannot replace C simply because a family strength table overlaps; any proposal needs a separate technical and project review.
Does a nickel-bearing designation guarantee impact performance?
No default impact result is promised. Establish whether the project requires testing and specify the complete specimen and acceptance conditions. Nickel chemistry or room-temperature elongation alone is not an impact-test certificate.
What if the offered report names ASTM rather than the ordered SA designation?
Refer it for documented ASME acceptance review before release. An ASTM certificate alone does not establish SA-302 compliance, and dual certification must have an agreed basis rather than a changed heading.
Send the Grade C acceptance requirements
Provide the SA designation and Code edition, unit system, dimensions, quantity, required delivery condition, tests and certificate form. Include nickel restrictions and any project toughness requirements explicitly so the proposed material and documentation can be assessed together.