ASTM A302 Grade D plate: identify the higher-nickel requirement
ASTM A302 Grade D is a manganese-molybdenum-nickel pressure-vessel plate grade. A useful Gangsteel enquiry identifies Grade D explicitly, rather than describing the material only by yield strength or by the A302 family name. The higher nickel requirement is part of the grade identity; a similar tensile result from another family member does not establish that the ordered material has been supplied.
The official public edition used here is A302/A302M-17(2022). Its Scope lists Grade D at 80–100 ksi [550–690 MPa] tensile strength and covers plate particularly intended for welded boilers and other pressure vessels. Chemistry, yield, elongation and ordinary delivery details below are separately labelled public references. They support preliminary purchasing review, while the ordered edition and project requirements remain the acceptance basis.
Check analysis identity before comparing the nickel result
Grade D’s public-reference nickel range is 0.70–1.00% for heat analysis and 0.67–1.03% for product analysis. These figures were independently checked in Grade D sources, not inferred from Grade C. Ask which analysis a quotation or report represents before comparing the number. Using a product-analysis range to assess a heat result can produce an apparently satisfactory comparison on the wrong basis.
| Element / thickness interval | Heat analysis | Product analysis |
|---|---|---|
| Carbon, max; up to 1 in. [25 mm], inclusive | 0.20 | 0.20 |
| Carbon, max; over 1 to 2 in. [over 25 to 50 mm], inclusive | 0.23 | 0.23 |
| Carbon, max; over 2 in. [50 mm] | 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 | 0.70–1.00 | 0.67–1.03 |
| Phosphorus, max | 0.025 | |
| Sulfur, max | 0.025 |
Source limits: the heat/product split follows a dated Grade D public compilation, checked against an undated compilation whose compressed alloy ranges are product-style. Those compressed values are not heat-analysis limits. The carbon note in the compilation applies its maxima to both analyses; it does not establish separate product phosphorus or sulfur limits. Those two product cells remain blank. Confirm the applicable chemical requirements in the purchased specification edition.
Manganese, silicon, molybdenum and nickel are ranges, not simply maxima. Carbon must be assessed against the correct thickness interval. If several plate thicknesses share one enquiry, retain a separate purchase line for each size and condition so the relevant carbon row is clear. A heat number and correctly labelled analysis provide a better starting point than a generic statement that the plate is a nickel alloy.
Read strength and elongation without substituting another grade
| Property | Grade D reference | Basis |
|---|---|---|
| Tensile strength | 80–100 ksi [550–690 MPa] | Official A302/A302M-17(2022) public Scope |
| Yield strength, minimum | 50 ksi [345 MPa] | Independent Grade D public compilations |
| Elongation, minimum; 8 in. [200 mm] gauge | 17% | Public-reference gauge-length minimum |
| Elongation, minimum; 2 in. [50 mm] gauge | 20% | Public-reference gauge-length minimum |
The yield and elongation entries were checked on Grade D columns in their own references, even though some other family members share strength figures. Elongation is tied to specimen gauge length: 17% and 20% are not thickness categories. A test result needs its reporting basis before it can be compared with the relevant requirement. Do not remove the gauge information to create one general elongation value.
Use inch-pound or SI units independently. The paired specification values are not exact conversions to mix within a single acceptance check. Keep the chosen system visible on the order, size schedule and report review. Similarly, Grade C is not interchangeable with Grade D because both are Mn-Mo-Ni grades. Its lower nickel band is a material distinction, not a naming variation that can be ignored after a tensile test.
Specify size and delivery together
The official public Scope limits maximum thickness by the chemical composition’s capacity to meet the specified mechanical requirements. No numerical specification cap or minimum is asserted here. A commercial size range and a specification coverage principle are different questions. Review the requested dimensions and condition for the actual order rather than using a catalogue size as proof of compliance or of supply capability.
A dated Grade D compilation restates ordinary delivery as normally as-rolled for 2 in. [50 mm] and under, with normalizing, stress relieving or both possible when ordered; plate over 2 in. [50 mm] is normalized. This is a compilation restatement, not a quotation from the paid official heat-treatment clause. Confirm it in the ordered edition and record the agreed delivery condition. This page does not prescribe treatment temperatures or a default quench-and-temper route.
The official ASTM abstract describes killed steel conforming to fine-grain requirements across the specification. That family-wide statement should not be read as a Grade-D-only benefit. Additional examinations, service-specific tests and fabrication conditions need their own order requirements. Higher nickel does not define a default impact energy, testing temperature or welding procedure, and no additional inspection package is promised merely by naming the grade.
Make the ASTM purchase requirement traceable
| Purchase item | What to state | What to reconcile |
|---|---|---|
| Specification | A302 or A302M, Grade D, ordered edition | Offer and document designation |
| Size schedule | Thickness, width, length, quantity and unit system | Each plate or identified purchase line |
| Material condition | Required delivery state and relevant fabrication constraints | Condition represented by reported tests |
| Inspection | Required tests, criteria and reporting details | Agreed examination scope, not assumed extras |
| Documents | Required certificate form and identification linkage | Plate marking, heat reference and supporting results |
Where Code delivery is required instead, consult the related ASME SA302 Grade D page. For the Mn-Mo family topic at a similar tensile level, see ASTM A302 Grade B plate. These are procurement contrasts, not technical sources or substitution approvals. An ASTM certificate is not automatic SA-302 acceptance, and the reverse is not automatic. Dual certification requires explicit agreement and supporting conformity evidence.
Buyer questions
What distinguishes Grade D from Grade C in an enquiry?
Grade D is the higher-nickel grade. Its labelled public-reference nickel limits are 0.70–1.00% heat and 0.67–1.03% product. Retain the drawing’s exact grade rather than requesting either grade on the assumption that a shared tensile range makes them interchangeable.
Which ASTM edition is identified on this page?
The official public listing used is A302/A302M-17(2022). Name the edition required by the contract on the order. Public compilations support the additional reference figures here; they are not presented as a full official table from the paid standard.
Does elongation change at the two gauge lengths because plate thickness changes?
No. The public-reference minima are 17% in 8 in. [200 mm] and 20% in 2 in. [50 mm]. These are different specimen gauges, not thin-plate and thick-plate bands. Review the reported gauge with the result.
Must every Grade D plate be delivered normalized?
Do not assume a blanket condition. The labelled compilation distinguishes plate at 2 in. [50 mm] and under from thicker plate and allows ordered conditions for the thinner category. Confirm the governing edition and state the agreed condition for each purchase line.
Are extra tests and dual certification included by default?
No default package is claimed. Specify the required tests, acceptance criteria and certificate form before purchase review. ASTM and ASME acceptance are separate questions; similar designations or a matching strength result do not automatically establish conformity to both.
Submit an ASTM Grade D size schedule
Include the ASTM designation and edition, size list, quantity, delivery condition and required inspection documents. Identify any proposed grade or certification deviation separately so it can be resolved against the purchase requirement.