ASTM A387
Chrome-moly alloy steel pressure-vessel plate
Covers chrome-molybdenum alloy steel pressure-vessel plate for elevated-temperature service, in grades such as 11, 12, 22 and 91, in Class 1 or Class 2 (Grade 91 in Class 2 only).
- Plate, sheet & strip
- ASME SA-387
- 1 grade supplied to it
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is ASTM A387?
ASTM A387 is the specification for chromium-molybdenum alloy steel pressure-vessel plate for elevated-temperature service. Common grades are 11 (1¼Cr-½Mo), 12 (1Cr-½Mo), 22 (2¼Cr-1Mo), 5 (5Cr-½Mo), 9 and 91 (9Cr-1Mo-V). Most grades come in Class 1 and the stronger Class 2. ASME adopts it as SA-387.
ASTM A387 at a glance
| Grades | 2, 12, 11, 22, 21, 5, 9, 91 |
|---|---|
| Classes | Class 1 and Class 2 (higher strength); Grade 91 is supplied in one strength level |
| Heat treatment | Annealed, or normalised and tempered |
| General requirements | ASTM A20 |
| ASME designation | SA-387 |
How to write ASTM A387 on a purchase order
Name the product, size, material specification and grade, the dimensional standard and the certificate. An example line:
Illustrative only — sizes, tests, inspection level and any project values come from your purchase specification.
ASTM A387 edition and verification status
Which edition we have confirmed, and what is still being checked before any numerical requirement is published here.
| Current edition | Not yet confirmed against the publisher listing |
|---|---|
| Full-text verification | In progress — numerical requirements are not published on this page |
| Edition on your order | The edition named in your purchase order or design code governs — confirm it with your enquiry |
What to know before ordering to ASTM A387
The points that decide whether material to ASTM A387 is accepted at inspection.
- Class 2 has higher tensile and yield strength than Class 1 of the same grade.
- Grade 11 (1¼Cr-½Mo) and Grade 22 (2¼Cr-1Mo) are the most common.
- Plates are supplied normalised and tempered or quenched and tempered.
Grades and products we supply to ASTM A387
| Grade | Product | Designation on the certificate |
|---|---|---|
| SA-387 Gr 11 Cl 2 | Plate | ASTM A387 Gr 11 Cl 2 · ASME SA-387 |
How ASTM A387 fits into an order
A purchase order line is only complete when it names the material standard, the dimensional standard and the inspection document. Miss one and the mill, the inspector and the buyer can each read the order differently.
Standards used with ASTM A387
Same family
ASTM A387 — questions buyers ask
What is ASTM A387?
ASTM A387 is the specification for chromium-molybdenum alloy steel pressure-vessel plate for elevated-temperature service. Common grades are 11 (1¼Cr-½Mo), 12 (1Cr-½Mo), 22 (2¼Cr-1Mo), 5 (5Cr-½Mo), 9 and 91 (9Cr-1Mo-V). Most grades come in Class 1 and the stronger Class 2. ASME adopts it as SA-387.
What is the difference between A387 Class 1 and Class 2?
Same chemistry; Class 2 is heat treated to higher tensile and yield strength.
Which grade is 2¼Cr-1Mo?
Grade 22. Grade 11 is 1¼Cr-½Mo and Grade 91 is 9Cr-1Mo-V.
Where can I compare Gr 11, Gr 22 and A516?
Our SA 387 Gr 11 vs Gr 22 vs SA 516 Gr 70 guide compares the three pressure-vessel plates.
Which grades do you supply to ASTM A387?
SA-387 Gr 11 Cl 2 — see the table on this page for the exact product and designation.
Do you supply certificates to this standard?
Yes. Material is supplied with mill test certificates to EN 10204 3.1 showing the standard, grade and heat number; 3.2 with third-party inspection on request.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026