SA515 vs SA516: start with the specification, not the grade number
SA515 and SA516 refer to different pressure-vessel plate specifications. Their ASTM counterparts, A515/A515M and A516/A516M, have different intended-service descriptions and grain requirements. A matching Grade 70 designation does not make the two materials interchangeable, even where their published tensile ranges overlap.
At Gangsteel, a useful comparison starts with the material line on the drawing: the complete designation, grade, edition and delivery condition. These identify what the buyer needs to purchase. A general description such as “boiler plate” leaves too much unresolved for a quotation or an engineering substitution review.
What the two families are intended to do
The following comparison uses the public ASTM abstracts and Scopes for A515/A515M-17(2022) and A516/A516M-25. For an ASME SA-515 or SA-516 order, the applicable Code and material-specification edition remain the acceptance basis.
| Selection point | A515/A515M | A516/A516M |
|---|---|---|
| Product description | Carbon-silicon steel pressure-vessel plate | Carbon steel pressure-vessel plate |
| Primary intended service | Intermediate- and higher-temperature service in welded boilers and other pressure vessels | Welded pressure vessels where improved notch toughness is important; moderate- and lower-temperature service |
| Deoxidation | Killed steel | Killed steel |
| Austenitic grain basis | Made to a coarse austenitic grain size practice | Conforms to fine austenitic grain size requirements |
| Grades in the public Scope | 60 [415], 65 [450], 70 [485] | 55 [380], 60 [415], 65 [450], 70 [485] |
Both families are killed steels. The distinction is therefore not “killed versus non-killed,” and coarse versus fine austenitic grain practice is not a commercial quality ranking. It is part of the specified material basis. A purchaser should retain that distinction rather than selecting a plate from its grade number alone.
Why similar tensile ranges do not establish equivalence
The public Scopes list the same tensile ranges for the grades common to both families. This overlap is useful for identifying grades, but it does not establish matching chemistry, heat treatment, toughness requirements or Code acceptance.
| Grade: inch-pound [SI] | A515 tensile range | A516 tensile range |
|---|---|---|
| 55 [380] | Not listed | 55–75 ksi [380–515 MPa] |
| 60 [415] | 60–80 ksi [415–550 MPa] | 60–80 ksi [415–550 MPa] |
| 65 [450] | 65–85 ksi [450–585 MPa] | 65–85 ksi [450–585 MPa] |
| 70 [485] | 70–90 ksi [485–620 MPa] | 70–90 ksi [485–620 MPa] |
Units and edition: Inch-pound and SI values are separate standard systems, not exact conversions to mix within an order. The published SI designation paired with Grade 70 is Grade 485. These are ASTM public-Scope tensile references, not an ASME acceptance table; SA orders follow the edition required by the governing Code.
A proposed change from one family to the other therefore needs review of the complete specification, not just a comparison of tensile results on two certificates. Even a result comfortably inside both published ranges does not demonstrate compliance with all the other requirements.
Temperature descriptions are not design limits
“Intermediate and higher” and “moderate and lower” describe the intended service of the specifications. They do not define a single temperature at which a buyer must switch from one family to the other. In particular, operation above ambient temperature is not, by itself, a reason to specify SA515.
The responsible designer must establish the construction-code basis, design temperatures and any toughness requirements for the actual component. A material name is not an assigned minimum design metal temperature, and a general comparison cannot provide an allowable-stress value. If the project needs impact testing, the order should identify the required test conditions and acceptance criteria rather than infer them from “lower-temperature” wording.
Keep heat treatment specific to each material
Delivery condition is a separate purchasing requirement. Do not transfer a normalizing thickness rule or heat-treatment schedule from the A516 family to A515 merely because both are pressure-vessel plates. Each material must be assessed under its own designation and ordered edition.
Where normalizing, stress relieving or another delivery condition is required, put that condition on the enquiry and agree the associated records. If fabrication will include further heat treatment, identify the relevant testing condition as well. A plate tested in one condition should not be assumed to represent every later fabrication cycle.
Resolving a drawing that mentions both families
A drawing, material requisition and purchasing schedule may use different shorthand. Resolve any conflict before comparing offers. “SA515/SA516” should not become an open choice for the supplier unless the engineering documents genuinely authorize alternatives and state the conditions attached to each.
- Identify which document controls the material selection and who approves changes.
- Separate ASTM and ASME designations, then specify the grade and required edition or Code year.
- State thickness, width, length, quantity and the unit system used throughout the order.
- Define delivery condition and any toughness, examination or other supplementary requirements.
- Record any proposed alternative as an engineering deviation, with its approval requirements, rather than silently changing the material line.
For the ASME-versus-ASTM designation question within the A516 family, see SA-516 vs A516. If the alternative on a mixed materials list is structural steel, SA516 vs A36 addresses a different selection issue.
When the specified material is Grade 70 in the A516 family, use our ASME SA516 Grade 70 steel plate or ASTM A516 Grade 70 steel plate page for the corresponding product enquiry. These routes keep the requested designation clear without implying that the two pressure-vessel families are substitutes.
Buyer questions about SA515 and SA516
Are SA515 and SA516 both killed steels?
Yes. The public ASTM abstracts identify killed steel for both corresponding families. Their grain requirements differ: A515 uses a coarse austenitic grain size practice, while A516 conforms to fine austenitic grain size requirements. “Killed” alone does not distinguish them or establish that a plate meets the other family’s requirements.
Can matching Grade 70 tensile results justify a substitution?
No, not on their own. The public ASTM ranges overlap, but a tensile result addresses only part of the specification. The responsible engineer must review the intended service, grain practice, chemistry, heat treatment and applicable Code requirements before authorizing a change. The purchasing documents should then record the approved designation and conditions.
Is there a fixed temperature for switching from SA516 to SA515?
There is no universal switching temperature established by the qualitative service descriptions. Selection depends on the component’s design basis and the applicable construction-code edition. Supply the design requirements and any required toughness testing to the responsible designer; do not select the family simply because the operating temperature is above ambient.
Can the same normalizing instruction be used for both families?
Do not assume so. Heat-treatment requirements belong to the particular specification, edition and ordered condition. A normalizing instruction taken from an A516 requirement is not evidence of the corresponding A515 requirement. State the condition needed for each material line, including any testing after agreed simulated fabrication heat treatment.
What if an enquiry describes the material only as “Grade 485 boiler plate”?
Ask for the full specification and unit-system basis. Grade 485 identifies the SI grade pairing shown in the public Scopes, but it does not distinguish A515 from A516 or establish an ASTM-versus-ASME order. Add the exact designation, edition, dimensions, delivery condition and supplementary requirements before treating offers as comparable.
Send a clearly defined plate enquiry
For a Gangsteel quotation, attach the controlling material requirement and identify the family actually specified.
- Exact designation, grade, edition or Code year, and unit system
- Plate dimensions and quantities
- Delivery condition, additional tests and any approved alternative-material requirements
If the material selection is unresolved, identify it as an open engineering decision rather than an assumed equivalent.
Availability, document scope and delivery terms are subject to the quotation for the specific order.