Steel Plate · Grade
ASTM A387 Grade 11 Plate
An A387 Grade 11 plate enquiry is settled by the standard scope, the grade and class, the heat-treatment condition, the dimensions, the service conditions, the testing and the documents — not by the grade name on its own.
Send the governing designation with its edition, the grade and class, the thickness, width and length, the required heat-treatment condition, any separate toughness or high-temperature property requirement, the quantity, the destination and the inspection documents the project requires, so the enquiry can be checked against the intended service before anything is quoted.
This is a chromium-molybdenum alloy plate specification written for elevated-temperature pressure service. Grade, class, heat treatment and any supplementary requirements are order-specific — confirm them against the project code before the enquiry is placed.
Price on request · Availability confirmed against the live enquiry
Selection
Choosing by the requirement, not the label alone
This specification covers several chromium-molybdenum grades, each split into classes, and other plate specifications can look similar on a drawing. Work from the service requirement inward, then narrow by grade, class, heat-treatment condition and dimensional range.
Start with the service temperature and the design code
A387 is written for chromium-molybdenum plate in elevated-temperature pressure service. The design temperature, the governing code and the pressure duty decide whether this specification is the right one to be comparing at all — that question comes before any grade comparison.
Name the grade and the class together
The standard covers several chromium-molybdenum grades, and the grade alone does not fix the acceptance basis: classes within a grade carry different heat-treatment requirements and different strength levels. Both the grade and the class have to be stated for an offer to be comparable.
Separate heat treatment, testing and dimensions
The heat-treatment condition the plate is supplied in is one input. Any elevated-temperature property, toughness or impact requirement is another. Thickness, width, length and tolerance basis are a third. Each is stated on its own line rather than bundled into one description.
Grades inside the same document, and plates bought to a different specification altogether, are comparison paths — not automatic substitutes. A neighbouring chromium-molybdenum grade or a carbon-steel pressure-vessel plate may reach a similar room-temperature strength and still behave differently at the design temperature, which is the condition that matters here.
Where the closest comparison sits
If the design temperature is not the driver, or the governing document turns out to be a carbon-steel specification, the ASTM A516 Grade 70 plate page covers the carbon-steel pressure-vessel route, and ASTM A283 Grade C plate covers the lower-strength structural-quality route. Where the duty is structural rather than pressure-retaining, the ASTM A572 Grade 50 plate page is the high-strength structural comparison to check. Reading them tells you which basis applies; it does not make them interchangeable with Grade 11.
Specification and dimension reviewThe class is part of the material, not the paperwork
Within this specification, the class determines the heat-treatment condition the plate is supplied in and the strength basis that goes with it. Two offers can carry the same grade and still not be the same material.
Where a requirement is genuinely still open, leave it open on the enquiry. A quote built on a guess cannot be checked against anything.
Specification
What to state so acceptance is unambiguous
Each input below is a separate ordering decision. Leaving one open — the class especially — is the usual reason two quotations turn out not to be the same plate.
The designation and its edition set the document. The wider alloy steel plate page covers the material family this grade belongs to, for confirming which other alloy specifications the project is choosing between.
| Input | What it fixes |
|---|---|
| Designation and edition | The elevated-temperature pressure-vessel plate specification the project names, with the edition where the design or the purchaser requires one. This is the document the order will be certified against. |
| Grade | Grade 11 named explicitly, along with any other grade in the document that the project is comparing it against. The chemistry and the strength basis follow from the grade rather than the standard. |
| Class | The class stated alongside the grade. Classes within this specification differ in the heat-treatment condition they carry and in the corresponding strength basis, so the class is part of the material definition — not a supplier preference. |
| Product form | Plate, as distinct from any other product form a similarly worded description might cover. The form is part of the acceptance basis, not an afterthought. |
| Thickness, width and length | Finished dimensions as required, in one coherent unit system, with the dimensional basis the project uses. Note any critical fit so tolerance can be checked before quotation. |
| Heat-treatment condition | The condition the plate is ordered and supplied in, which for this specification is tied to the class. Stated on its own line, not bundled with the test requirement — a stated condition does not by itself define a test result. |
| High-temperature and toughness testing | Whether elevated-temperature properties, an impact result, or both are required, at which test temperature and to which acceptance criterion — and whether they come from the specification or from a project or code addition. Confirm against the project rather than assuming either is included. |
| Surface, edge and processing | Any requirement on surface condition, edge preparation, cutting, bevelling or marking, and whether that processing is part of the supply scope. |
| Inspection and documents | The certificate type and any additional testing, inspection or third-party witness the purchaser specifies. Agreed at enquiry stage, not assumed from the grade. |
| Quantity and destination | Ordered quantity in plates and mass, the delivery point or port, delivery term and Incoterm with its named place, and the consignee. These drive packing, shipment documents and the commercial basis. |
The heat-treatment condition and any high-temperature or toughness requirement are recorded separately. A stated condition does not by itself define a test result, and neither one stands in for the other on the order or on the certificate review.
Plate edge, surface and identificationSpecification Check
Check the plate selection against the order
Enter the details the order will actually be placed on. The check flags what is still missing before an enquiry is prepared, so an apparently comparable option is not treated as equivalent.
Leave anything genuinely undecided blank rather than filling it with an assumption — the gap is what the technical review needs to see.
Still to resolve before an enquiry can be checked:
- Intended service / design duty
- Governing standard or specification (with edition)
- Grade
- Class
- Thickness (mm)
- Quantity
- Destination / delivery point
Copyable summary
ASTM A387 Grade 11 Plate — specification summary Service / design duty: — not stated Standard / specification: — not stated Grade: — not stated Class: — not stated Thickness: — not stated Width: — not stated Length: — not stated Heat-treatment condition: — not stated High-temperature / toughness requirement: — not stated Surface / edge / processing: — not stated Quantity: — not stated Destination: — not stated Required documents: — not stated Price, availability, mill origin, lead time and certification are confirmed against the live enquiry.
Verification
Confirming the plate matches the order
Verification follows the purchase specification. Ask for the records the project requires, and match what arrives to what was ordered — against the declared grade and class rather than against the familiar grade name.
Preparation for fabrication and dispatch- Match the material identification to the ordered designation and edition, grade and class, heat number, dimensions and heat-treatment condition before the plate is cut — once it is processed, the identification is much harder to reconstruct.
- Check the class on the certificate against the class on the order. Because the class carries the heat-treatment basis, a class mismatch is a material mismatch, not a paperwork detail.
- Keep the heat-treatment condition and any high-temperature or toughness requirement on separate lines of the order and of the certificate review, so acceptance is checked against the right figure on the right document.
- Confirm any third-party inspection, code approval or project approval against the actual supply — they follow the order and the works, and are not implied by the grade designation on this page.
Certificates, code approvals and any additional tests are confirmed for the actual supply. Nothing on this page should be read as confirming them for a particular order.
Applications
Where this plate specification is called for
Application fit depends on what the plate has to do in service and how it will be fabricated. The same grade and class can still carry different testing, weldability and documentation controls from one duty to the next.
Elevated-temperature pressure equipment
The duty this specification is written around — vessels, drums and similar components operating hot enough that elevated-temperature properties, rather than room-temperature strength, set the requirement.
View this applicationPressure-retaining fabricated items
Where the plate is formed and welded into a vessel or similar item and the design names the plate specification. The governing code still sets the acceptance basis, which can differ from one project to the next.
View this applicationWear and abrasion duty
Where abrasion and impact, not temperature or pressure, set the requirement. Wear service resolves to a different material and hardness route entirely — read this one as a comparison path to rule out, not a match.
View this applicationUse an application path only where the duty actually matches. One of the paths above exists to help you check that the duty is not the one this specification covers — that check is worth making before the enquiry, not after delivery. Oil and gas is the industry where elevated-temperature and pressure duty most often originate.
GCC Supply
Sourcing into the Gulf without moving the specification
The technical specification stays fixed while the destination-specific import path, consignee requirements and shipment documents are checked for the actual order.
Steel plate — United Arab Emirates
Steel plate — Saudi Arabia
Steel plate — Qatar
Steel plate — Kuwait
Steel plate — Bahrain
Steel plate — OmanCustoms classification, conformity requirements and duty treatment follow from the actual goods and destination, and are confirmed for the specific shipment rather than quoted generally.
Technical Note
The purchasing sequence that avoids a costly re-quote
Identify the service requirement and the governing specification first, then lock the designation and edition, the grade, the class, the heat-treatment condition, the dimensions, the testing and the documents.
Doing it in that order keeps offers comparable. Working the other way round — collecting quotes against a familiar grade name and trying to reconcile the specifications afterwards — is how two offers that both read “A387 Grade 11” turn out to differ in class, heat treatment, testing or acceptance basis.
The practical gain is not a claim about any one supplier. It is a clearer comparison between compliant offers, earlier visibility of a requirement nobody has resolved yet, and a more complete enquiry for technical review — which is what shortens the loop between enquiry and a firm offer.
Nothing on this page is a material property, a stock position or a certificate. It sets out what an enquiry for this grade has to contain so that what comes back can be checked against the project requirement rather than against a name.
Selection context for this page draws on ASTM International — A387/A387M (information date 2026-10-06). The specification sets the scope for chromium-molybdenum pressure-vessel plate for elevated-temperature service, and the grade, class, heat treatment and supplementary requirements are order-specific. This source is used for selection context, not for supplier-specific claims.
- 01
Define the service and the design code
Establish the design temperature, the pressure duty and the code that governs it. This decides whether the specification on the drawing is the right one to be quoting against at all.
- 02
Lock the designation, edition, grade and class
Name the specification with its edition, Grade 11 explicitly, and the class — the class carries the heat-treatment basis, so it is part of the material definition.
- 03
Fix heat treatment and the testing basis
State the heat-treatment condition the order is placed on, and separately any elevated-temperature property, toughness or impact requirement — at what temperature and to which acceptance criterion.
- 04
Settle dimensions and tolerances
Thickness, width, length, tolerance basis and unit system, with any critical fit called out so it can be checked before quotation.
- 05
Add quantity, destination and documents
Quantity in plates and mass, delivery point, Incoterm and consignee, plus the certificate type and inspection records the project requires.
- 06
Review processing and commercial terms
Cutting, edge preparation and marking scope, then the commercial terms, before the order is confirmed. Price, availability and lead time are confirmed against this enquiry.
FAQ
Grade 11 plate sourcing, answered directly
Each answer depends on the project specification and the actual order conditions. Where a requirement is order-specific, it is confirmed against the enquiry rather than assumed here.
Which standard, grade and class should be stated on the enquiry?
State the specification the project names, with its edition where the design or the purchaser requires one, Grade 11 explicitly, and the class. The standard on its own does not identify the grade, the grade does not identify the class, and the class carries the heat-treatment basis and the corresponding strength level. All four have to be named so the quotation and the material test certificate can be matched against the plate actually shipped.
When does heat treatment or toughness testing matter?
These are two separate decisions and should be stated separately. The heat-treatment condition describes how the plate is supplied and is tied to the class within this specification; the testing requirement sets what the material must demonstrate, at a stated test temperature and to a stated acceptance criterion. A project can call for one without the other. State both if both apply, and do not assume a named heat-treatment condition implies a particular test result.
Which dimensions and tolerances govern acceptance?
Give the required thickness, width and length, keep one coherent unit system, and state the tolerance basis the project uses rather than leaving the supplier to choose one. Plate tolerances are tied to the governing standard and can vary with thickness. Where a fabrication has a critical fit, say so on the enquiry so the tolerance can be checked before quotation rather than discovered after delivery.
What inspection documents are required?
Provide, or ask for, the document set the project requires — typically the material test certificate carrying the chemical and mechanical evidence for the declared grade and class, heat and lot traceability, and any additional testing, inspection or third-party witness the purchaser specifies. Where a certificate type or an additional test is needed, state it at enquiry stage so it can be scheduled and costed. Nothing on this page should be read as confirming certification for a particular supply.
Can a related grade be substituted for Grade 11?
Not automatically. Grades inside the same document differ in chemistry and in the strength basis applied at temperature, and classes within a grade differ in heat treatment. A plate reaching a similar room-temperature strength under a different specification may behave differently at the design temperature, which is the condition that matters here. A substitution is a design decision for the responsible engineer, made against the governing code and the service conditions — not inferred from two grade names looking comparable.
What destination details are needed for a firm commercial offer?
State the delivery point or port, the required delivery term and Incoterm with its named place, the consignee and any document set the destination requires. Customs classification, conformity requirements and duty treatment follow from the actual goods and the actual destination, so they are confirmed for the specific shipment rather than quoted generally. Availability, price and lead time are likewise confirmed against the live enquiry.
Request a Quote
Provide the standard and edition, Grade 11 with its class, the intended service and design temperature, the thickness, width and length, the required heat-treatment condition, any high-temperature, toughness or impact-testing requirement, the quantity, the destination, the documents and any cutting, testing or inspection scope. Price is always on request.
If a requirement is still undecided, state it explicitly — the class especially. The technical review can then identify what has to be resolved before a commercial offer is finalised.
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