What is ASME SA387 Gr.11?
Hot-rolled alloy steel plate ASME SA387 Gr.11 (1.25Cr-0.5Mo) is a classic chromium‑molybdenum (Cr‑Mo) heat-resistant steel complying with ASME SA-387 / ASTM A387M standards. It is engineered for welded boilers and pressure vessels operating under medium-to-high temperature and high-pressure service conditions. ASME SA387 Gr.11 steel plate is available in two delivery classes: Class 1 and Class 2. Among them, Class 2 (supplied under Normalized and Tempered / N+T condition) serves as the preferred material for EPC projects in the global petrochemical, power and hydrogen energy sectors, thanks to its stable microstructure, reliable low-temperature toughness, excellent creep resistance and hydrogen attack resistance.
GNEE Steel is a professional supplier and exporter of ASME-standard pressure vessel steel plates, with 18 years of extensive experience serving global engineering contractors, refineries and power plant equipment manufacturers. We maintain substantial stock of hot-rolled SA387 Gr.11 CL1 and CL2 steel plates. All products are manufactured in strict accordance with ASME specifications, and complete Mill Test Certificates (MTC) conforming to EN 10204 3.1/3.2 can be provided.
If you are sourcing ASME-compliant SA387 Gr.11 boiler and pressure vessel plates with full certification and stable quality for your ongoing boiler or pressure vessel project, contact GNEE Steel today to get an accurate project-based quotation and free technical parameter verification.
Main Performance Characteristics of ASME SA387 Gr.11 PVQ Steel Plate
Our ASME SA387 Gr.11 steel plate exhibits a creep rupture strength of approximately 115 MPa for 100,000 hours at 450°C; the long-term creep rupture strength remains roughly 72 MPa at 500°C. The recommended maximum continuous service temperature is 540°C, enabling resistance to creep deformation of pressure vessels under pressure and cyclic thermal loads.
With a balanced chromium‑molybdenum ratio and stringent control of detrimental trace elements, our ASME SA387 Gr.11 steel plate satisfies relevant NACE service requirements for moderately sour and hydrogen-containing environments. Implementation of standardized Post-Weld Heat Treatment (PWHT) can significantly reduce risks of hydrogen-induced cracking. This material is widely applied in medium-pressure hydrogenation units.
The low-carbon matrix lowers susceptibility to cold cracking. For 60 mm thick plate adopting a preheat temperature of 180°C plus standard PWHT at 630–670°C, the tensile strength of welded joints is stably maintained within the range of 490–570 MPa, and welding crack defects are rarely detected during routine non-destructive testing.
After normalized and tempered heat treatment, SA387 Gr.11 CL2 generally achieves Charpy V-notch impact energy ≥47 J under impact testing at -29°C. Its microstructure consists of uniform ferrite‑bainite. No substantial toughness degradation occurs after simulated prolonged Post-Weld Heat Treatment.
Our hot-rolled ASME SA387 Gr.11 steel plate supports flame cutting, plasma cutting, cold bending and drilling. When formed with a minimum cold bending radius ≥3t (t = plate thickness), microcracks are unlikely to emerge on the plate surface.
ASME SA387 Gr.11 Hot Rolled Plate Specification
| Parameter | Details |
|---|---|
| Standard | ASTM A387 / ASME SA-387 |
| Form | Hot Rolled Plate |
| Thickness | 5 mm – 150 mm (0.20 in – 5.90 in) |
| Width | Up to 4,500 mm (177 in) |
| Length | Up to 18,000 mm (708 in) |
| Surface Finish | Hot Rolled, Descaled |
| Heat Treatment | Normalised and Tempered / Annealed |
ASME SA387 Gr.11 Alloy Steel Plate Chemical Composition
| C | Mn | P | S | Si | Cr | Mo |
| 0.04 ~ 0.17 | 0.35 ~ 0.73 | ≤0.025 | ≤0.025 | 0.44 ~ 0.86 | 1.00-1.50 | 0.44 ~ 0.65 |
ASME SA387 Gr.11 Hot Rolled Alloy Steel Plate Mechanical Property
| A387 / SA387 Grade 11 | Class 1 | Class 2 |
| Tensile Strength (ksi) | 60-85 | 75-100 |
| Tensile Strength (MPa) | 415-585 | 515-690 |
| Yield Strength (ksi) | 35 | 45 |
| Yield Strength (MPa) | 240 | 310 |
| Elongation in 200mm (%) | 19 | 18 |
| Elongation in 50mm (%) | 22 | 22 |
ASME SA387 Gr.11 HR Plate Thickness Tolerance
| Nominal Thickness (mm) | Thickness Tolerance (mm) |
|---|---|
| 6 ~ 25 | +1.2 / -0.3 |
| 25 ~ 50 | +1.5 / -0.4 |
| 50 ~ 100 | +2.0 / -0.5 |
| 100 ~ 150 | +2.5 / -0.6 |
Manufacturing Process Flow of ASME SA387 Gr.11 Steel Plate
Smelting
Electric arc furnace smelting → LF refining → VD vacuum degassing. Harmful impurities including P, S, Sn, Sb and As are strictly controlled to mitigate temper embrittlement risk.
Continuous casting / Ingot casting
Qualified steel slabs are produced followed by internal defect inspection.
Slab reheating
Heating temperature 1220–1280°C with uniform soaking to prevent inhomogeneous microstructure after rolling.
Controlled hot rolling
Multi-pass hot rolling. Finishing temperature is controlled to achieve a uniform ferrite-bainite microstructure.
Post-rolling cooling
Controlled cooling is adopted to avoid excessive internal stress.
Heat treatment (N+T for CL2)
Normalizing and tempering performed in accordance with technical requirements. CL1 material may be supplied in the as-rolled or annealed condition.
Surface finishing
Descaling and surface inspection to eliminate surface cracks and defects.
Non-destructive testing
100% Ultrasonic Testing (UT) complying with SA-435 / SA-578 standards (available upon request).
Sampling test
Chemical analysis, tensile test, hardness test and Charpy impact test.
Marking & packaging
Permanent marking of heat number, steel grade, dimensions and heat treatment condition; seaworthy export packaging.
Core ASME SA387 Gr.11 Boiler & Pressure Vessel Plate Applications
Boiler Shells and Steam Drums
SA387 Gr.11 Class 2 steel features excellent creep resistance and thermal stability, helping maintain structural integrity during long-term operation and repeated thermal cycles.
Pressure Vessels
Facilities such as petrochemical plants, refineries and power plants require materials capable of withstanding high pressure and elevated temperatures. Thanks to its dependable mechanical properties and favourable weldability, SA387 Gr.11 Class 2 steel is suitable for fabrication of large pressure-containing equipment.
Heat Exchangers and Process Heaters
Heat exchangers and process heaters are continuously exposed to high-temperature process fluids and thermal cycling environments. Chromium and molybdenum alloying elements enhance oxidation resistance and high-temperature strength, extending service life and lowering maintenance requirements for equipment.
Steam Headers and Process Vessels
Steam headers, separators and other process vessels must retain long-term strength and dimensional stability under fluctuating temperature and pressure. SA387 Gr.11 Class 2 steel delivers consistent reliable performance, hence it is widely adopted in power generation, oil & gas and petrochemical industries.
Why Choose GNEE Steel?
Stock Availability: SA387 Gr.11 CL1/CL2 hot-rolled steel plates available from stock for rapid delivery to urgent projects.
Custom Sizing: Flame, plasma, and laser cutting services based on customer drawings to cut plates to required dimensions and minimize processing waste.
Comprehensive Export Services: Professional sea-worthy packaging, IPPC-compliant wooden pallets, customs documentation, and global logistics coordination.
Technical Support: Material selection advice, welding procedure recommendations, comparisons between SA387 Gr.11 and Gr.22, and equivalent grade references.
GNEE provides full lifecycle service from material selection, inspection, processing to export shipment. Free sample testing and free technical consultation are available for all global clients.
FAQ
What is the equivalent Chinese grade of SA387 Gr.11?
The equivalent Chinese standard grade for ASME SA387 Gr. 11 (specifically Class 2) is 14Cr1MoR under the GB 713 standard for pressure vessel and boiler steel plates.
What is the maximum continuous service temperature of SA387 Gr.11?
The maximum continuous service temperature for ASME SA387 Grade 11 is typically up to 540°C (1004°F), depending on the specific design code and allowable creep stress limits.
Can SA387 Gr.11 be welded easily?
Yes, SA387 Gr.11 can be welded using standard industrial methods like SMAW, GTAW, and GMAW, but it requires strict heat controls and specific procedures to prevent cracking.
What is SA387 Gr.11 different from SA516 Grade 70?
SA387 Gr.11 differs from SA516 Grade 70 primarily in material composition, temperature limits, and structural applications. SA387 Gr.11 is a chromium-molybdenum alloy steel built for high-heat use, while SA516 Grade 70 is a standard carbon steel made for moderate and lower temperatures.
Is SA387 Gr.11 suitable for boilers?
Yes, ASME SA387 Grade 11 is explicitly designed and highly suitable for welded boilers and pressure vessels operating at elevated temperatures.
