SA-387 Gr 11 Cl 2 PlateASTM A387 · Manufacturer, stockist & exporter, India
Also sold as ASTM A387 Gr 11 Cl 2 · 1¼Cr-½Mo plate · Chrome-moly plate · SA387 Gr 11 Cl 2
SA-387 Gr 11 Cl 2 plate is supplied hot rolled to ASTM A387 Gr 11 Cl 2, as full mill plates or cut to your drawing for structural and pressure parts. It is a chrome-moly pressure-vessel plate, chosen for hot, high-pressure reactors and heat exchangers. Kanak Steel & Engineering Co. supplies it with EN 10204 3.1 mill certificates from Mumbai to buyers across India, the Gulf, South-East Asia, South America, Europe, the UK and the USA.
- Stock & mill supply
- EN 10204 3.1 / 3.2
- Mill test certificates
- Export packing
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is SA-387 Gr 11 Cl 2 Plate?
SA-387 Gr 11 Cl 2 plate is a chrome-moly pressure-vessel plate supplied as plate to ASTM A387 Gr 11 Cl 2. Buyers specify it for hot, high-pressure reactors and heat exchangers. It is also sold as ASTM A387 Gr 11 Cl 2, 1¼Cr-½Mo plate, Chrome-moly plate.
- What it is
- Chrome-moly pressure-vessel plate
- Standard
- ASTM A387 Gr 11 Cl 2 · ASME SA-387
- Thickness
- Plate is defined under ASTM A20 by width and thickness — roughly 4.6 mm and over for plate wider than 48"
- Density
- 7.85 g/cm³
- Supplied as
- Hot rolled · as-rolled or normalised · cut to size
- Best at
- Hot, high-pressure reactors and heat exchangers
SA-387 Gr 11 Cl 2 Plate Specification & Sizes
| Material standard | ASTM A387 Gr 11 Cl 2 · ASME SA-387 · ASME SA-387 |
|---|---|
| General requirements | ASTM A20 — dimensions, tolerances and finishes |
| Grade | SA-387 Gr 11 Cl 2 |
| Thickness | Plate is defined under ASTM A20 by width and thickness — roughly 4.6 mm and over for plate wider than 48" |
| Width × length | 1000 / 1250 / 1500 / 2000 / 2500 mm × up to 6000 mm, or cut to drawing |
| Condition & finish | Hot rolled · as-rolled or normalised · shot-blasted and primed on request |
| Cutting | Cut to size — rectangles, strips, circles & rings |
| Testing | Chemical & mechanical per heat · UT to A435 / A578 · impact tests on request |
| Documents | EN 10204 3.1 · 3.2 with third-party inspection · packing list · certificate of origin |
SA 387 Gr 11 Class 1 vs Class 2
Grade 11 is 1¼Cr-½Mo-Si steel plate; the class sets the strength. Chemistry is the same for both. Class 2 is heat treated to a higher tensile and yield range, so designers use it to save wall thickness on reactors and drums; Class 1 is chosen where lower hardness and easier forming matter more.
Governing specification: ASTM A387 / ASME SA-387. Numerical specification requirements are published only after the applicable current standard edition has been verified.
Under technical review for TDS.
| Property | Class 1 | Class 2 |
|---|---|---|
| Tensile strength | As specified | As specified |
| Yield strength, min | As specified | As specified |
| Elongation in 200 mm, min | As specified | As specified |
| Elongation in 50 mm, min | As specified | As specified |
| ASME P-Number | P-No. 4, Group 1 | P-No. 4, Group 1 |
SA 387 Gr 11 Heat Treatment, Welding & PWHT
Plates are supplied annealed, or normalised and tempered. Accelerated cooling (air blast or liquid quench) followed by tempering is allowed only if the purchaser agrees. A387 sets a minimum tempering temperature for each grade — 620 °C (1150 °F) for Grade 11.
Fabrication is where chrome-moly plate goes wrong. Preheat, interpass control and post-weld heat treatment (PWHT) are set by your construction code — ASME VIII Div 1 (UCS-56) and B31.3 give different temperature ranges and hold times for P-No. 4 — and the PWHT must not drop the plate below its Class 2 minimums.
That is why buyers order simulated PWHT of the mechanical test coupons (ASTM A20 supplementary requirement S3): the mill heat-treats the test pieces to your PWHT cycle and reports the properties after it.
| Supply condition | Annealed, or normalised & tempered |
|---|---|
| Min. tempering temperature | 620 °C (1150 °F) |
| Matching filler | ER80S-B2 (GTAW / GMAW) · E8018-B2 (SMAW) |
| Preheat & PWHT | Per your code and WPS for P-No. 4 material and the thickness |
| Simulated PWHT | Order A20 S3 and give the PWHT temperature, hold time and number of cycles |
| Impact testing | Not mandatory — order Charpy tests (A20 S5) at your test temperature |
| Ultrasonic testing | A20 S8 (ASTM A435) or S12 (ASTM A578) |
| Equivalents (approx.) | EN 10028-2 13CrMoSi5-5 (1.7336) · JIS G 4109 SCMV 3 |
SA 387 Gr 11 for Hydrogen and High-Temperature Service
1¼Cr-½Mo is chosen over carbon steel (such as SA 516 Gr 70) when the vessel runs hot or in hydrogen: chromium and molybdenum give creep strength and resistance to high-temperature hydrogen attack. Refinery designers check the operating point against the API RP 941 (Nelson) curves; heavy-wall hydroprocessing vessels in this alloy follow API RP 934-C.
For long service in the temper-embrittlement range, project specifications may add impurity limits (J-factor, X-bar) and step-cooling tests. These are not part of A387 itself — put them on the order.
| Plate | Alloy | Typical choice for |
|---|---|---|
| SA 516 Gr 70 | Carbon steel | Vessels at moderate and lower temperatures |
| SA 387 Gr 11 | 1¼Cr-½Mo | Hot reactors, drums and exchangers; moderate hydrogen partial pressure |
| SA 387 Gr 22 | 2¼Cr-1Mo | Higher temperature and hydrogen partial pressure |
| Matching pipe & forgings | Same alloy family | A335 P11 pipe · A234 WP11 fittings · A182 F11 flanges |
SA-387 Gr 11 Cl 2 Plate Cut to Size
Most 387-11 plate leaves us as pieces, not full mill plates. Cutting from a full plate means you pay only for what you use, and each piece keeps the heat number of the plate it came from.
| Full & part plates | Full mill plates, halves and quarters |
|---|---|
| Rectangles & strips | To your list of finished sizes, or to a drawing |
| Circles & rings | Blanks for blind flanges, covers, tube sheets and nozzles |
| Machining allowance | State finished size and allowance; thermally cut edges are normally machined back |
| Traceability | Heat number transferred to every piece before cutting |
Send a cutting list or DXF; we nest pieces to reduce off-cut and quote per piece.
SA-387 Gr 11 Cl 2 Plate Chemical Composition
Under technical review for TDS.
| Element | Current requirement |
|---|---|
| Chromium | As specified |
| Molybdenum | As specified |
| Carbon | As specified |
| Manganese | As specified |
| Silicon | As specified |
| Phosphorus | As specified |
| Sulphur | As specified |
Numerical specification requirements are published only after the applicable current standard edition has been verified. Governing specification to be verified: ASTM A387 Grade 11.
SA-387 Gr 11 Cl 2 Plate Mechanical Properties
Under technical review for TDS.
| Property | Current requirement |
|---|---|
| Tensile strength | As specified |
| Yield strength | As specified |
| Elongation (50 mm) | As specified |
Numerical specification requirements are published only after the applicable current standard edition has been verified. Governing specification and condition to be verified: ASTM A387 Grade 11 — Class 2.
Density & Physical Properties
| Property | Value |
|---|---|
| Density | 7.85 g/cm³ |
| Melting range | 1420 – 1530 °C |
| Magnetic | Magnetic |
SA-387 Gr 11 Cl 2 Equivalent Grades
SA-387 Gr 11 Cl 2 Plate Weight Chart & Calculator
Use this to budget freight and price per piece. Weight (kg) = length (m) × width (m) × thickness (mm) × 7.85.
Example: 2000 × 1000 × 10 mm
2.0 × 1.0 × 10 × 7.85 = 157.0 kg
Total weight —
| Thickness | 2000 × 1000 plate | Per m² |
|---|---|---|
| 5 mm | 78.5 kg | 39.3 kg |
| 6 mm | 94.2 kg | 47.1 kg |
| 8 mm | 125.6 kg | 62.8 kg |
| 10 mm | 157.0 kg | 78.5 kg |
| 12 mm | 188.4 kg | 94.2 kg |
| 16 mm | 251.2 kg | 125.6 kg |
| 20 mm | 314.0 kg | 157.0 kg |
| 25 mm | 392.5 kg | 196.3 kg |
Six-digit Harmonized System heading (iron and steel, chapter 72–73). Your country adds its own digits — confirm with your customs broker. All HS codes.
SA-387 Gr 11 Cl 2 Plate Price — What Decides It
Two quotes for "387-11 plate" can differ by 20% and both be fair. We quote 387-11 plate per kg for full sizes and per piece for cut sizes. These six things move the price per kg, so you can compare offers like for like.
SA-387 Gr 11 Cl 2 Plate Testing & Inspection
Plate goes into pressure parts and heavy sections, so it is inspected for internal soundness and flatness as well as chemistry. These tests are added to the order and reported on the certificate or as separate reports.
| Ultrasonic testing | Straight-beam UT to ASTM A435 (A20 supplementary requirement S8) or A578 (levels A, B, C) |
|---|---|
| Flatness & dimensions | Per ASTM A20 tables for thickness, width and length |
| Impact testing | Charpy impact tests at the specified temperature (ASTM A20 supplementary requirement S5) |
| PMI | Alloy verification on each plate, or each cut piece if required |
| Third-party inspection | Witness by your inspector or agency, with an EN 10204 3.2 certificate |
UT checks the plate body along a scan grid and a band along each edge, where laminations matter most for welding.
SA-387 Gr 11 Cl 2 Plate Applications
Plate is chosen for pressure-bearing walls, heavy sections and parts machined from solid.
How your 387-11 plate order runs
- 01Enquiry review — we confirm size, standard edition and documents against your MR or drawing.
- 02Heat selection & PMI — the mill certificate is checked against your order; PMI before processing is available on request.
- 03Processing — cutting to your sizes, with heat numbers transferred to every piece.
- 04Inspection — your third-party inspector witnesses, or we share photos and test reports.
- 05Packing & dispatch — seaworthy packing from Nhava Sheva (JNPT), Mumbai, FOB or CIF, documents sent before the vessel sails.
Fabricating Heavy SA-387 Gr 11 Cl 2 Plate
Shells, heads and tube sheets mean thick sections and multi-pass welds. These are the points that decide whether 387-11 plate keeps its corrosion resistance after fabrication; matching filler is ER80S-B2 / E8018-B2.
General guidance only; follow your approved WPS, PQR and design code.
| Preheat | Set by thickness and carbon equivalent per your WPS and code. |
|---|---|
| PWHT | Post-weld heat treatment where the code or service requires it. |
| Joint preparation | Double-V or J-prep on heavy plate to reduce weld volume. |
How to Order SA-387 Gr 11 Cl 2 Plate: RFQ Checklist
Get an accurate quote the first time. Copy this list into your enquiry:
- Standard and edition — e.g. ASTM A387 Gr 11 Cl 2-latest
- Thickness × width × length, and number of pieces
- Full plates or cut pieces (attach drawing)
- Certificate type — 3.1 or 3.2, and the inspection agency
- Extra tests — UT, intergranular corrosion
- Delivery port, Incoterm and required date
SA-387 Gr 11 Cl 2 plate for export
FOB / CIF · Nhava Sheva (JNPT), MumbaiSA-387 Gr 11 Cl 2 plate — questions buyers ask
What is the difference between SA 387 Gr 11 Class 1 and Class 2?
Same chemistry, different strength: Class 2 is heat treated to a higher tensile and yield range than Class 1. The applicable numerical requirements depend on the governing specification edition; Kanak Steel is verifying the current standard text before publishing them.
What is SA 387 Gr 11 made of?
It is a 1¼Cr-½Mo-Si chrome-moly plate steel. The chemical requirements are set by ASTM A387 / ASME SA-387; Kanak Steel is verifying the current standard text before publishing numerical limits.
What P-Number is SA 387 Gr 11?
P-No. 4, Group 1 under ASME Section IX, which sets the preheat and PWHT rules your WPS follows.
Does SA 387 Gr 11 need PWHT?
Usually yes. Your code (ASME VIII or B31.3) sets PWHT for P-No. 4 by thickness; order simulated PWHT (A20 S3) so the mill certifies properties after your cycle.
What is the EN equivalent of SA 387 Gr 11?
The closest is EN 10028-2 13CrMoSi5-5 (1.7336). 13CrMo4-5 is the 1Cr-½Mo grade and corresponds to A387 Grade 12. Check properties before substituting.
Is impact testing included in SA 387 Gr 11?
No. Charpy testing is a supplementary requirement (ASTM A20 S5) — state the test temperature and energy on the order.
Is SA-387 Gr 11 Cl 2 the same as ASTM A387 Gr 11 Cl 2?
ASTM A387 Gr 11 Cl 2, 1¼Cr-½Mo plate, Chrome-moly plate are names used for SA-387 Gr 11 Cl 2, and plate is ordered to ASTM A387 Gr 11 Cl 2 whichever name is on the enquiry.
What thickness counts as SA-387 Gr 11 Cl 2 plate?
For SA-387 Gr 11 Cl 2, plate is defined under ASTM A20 by width and thickness — roughly 4.6 mm and over for plate wider than 48"; thinner material is outside ASTM A20, which covers plate only. Order the form that matches your drawing thickness.
What is the price of SA-387 Gr 11 Cl 2 plate per kg?
It moves with steel mill prices, so a fixed list price is out of date within days. Thickness, cut size, quantity and documents also change it. Send your size and quantity and we quote the same working day.
Do you supply ultrasonically tested SA-387 Gr 11 Cl 2 plate?
Yes, UT can be added to the order — to ASTM A435 or the level your specification states. The UT report is supplied with the mill certificate.
Can SA-387 Gr 11 Cl 2 plate be cut into circles and rings?
Yes. Blanks for blind flanges, covers and tube sheets are cut from plate to your drawing, with the heat number marked on every piece.
What machining allowance should I leave on cut plate?
It depends on the cutting method and finished tolerance. Give us the finished size and your allowance; thermally cut edges are normally machined back to sound metal.
How heavy is a SA-387 Gr 11 Cl 2 plate?
Weight (kg) = length (m) × width (m) × thickness (mm) × 7.85. A 2000 × 1000 × 10 mm plate weighs about 157 kg; use the calculator on this page for your size.
What documents come with an export shipment?
An EN 10204 3.1 mill certificate (or 3.2 with a third-party inspector), commercial invoice, packing list with heat numbers, and certificate of origin. Test reports are added for any extra tests ordered.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026