What is ASME SA387 Gr.11 Steel Plate?
ASME SA387 Gr. 11 steel features a nominal alloy composition of 1.00% to 1.50% chromium and 0.45% to 0.65% molybdenum (in accordance with ASTM A387/ASME SA387 specifications). Compared to conventional carbon steels, this grade delivers superior oxidation and creep resistance, leading to its widespread application in refinery process vessels, power plant boilers, heat exchangers, and petrochemical equipment designed and fabricated to ASME codes.
Selecting the appropriate chromium-molybdenum (Cr-Mo) pressure vessel steel during the design phase not only enhances the long-term operational reliability of the equipment but also minimizes maintenance requirements throughout the vessel's entire service life.
Are you looking for ASME SA387 Gr. 11 steel plates that comply with EN 10204 3.1 or 3.2 certification requirements, undergo ultrasonic testing (UT), and feature complete mill traceability? GNEE Steel is dedicated to providing global pressure vessel fabricators with project-oriented material selection consulting, custom fabrication services, and reliable export solutions.
The Specification of ASME SA387 Gr.11 Steel Plate
| Item | Specification |
|---|---|
| Product Name | ASME SA387 Grade 11 Alloy Steel Plate |
| Standard | ASME SA387 / ASTM A387 |
| Grade | Grade 11 Class 1 (Cl.1), Grade 11 Class 2 (Cl.2) |
| Steel Type | Chromium-Molybdenum (Cr-Mo) Alloy Pressure Vessel Steel |
| Chromium Content | 1.00–1.50% |
| Molybdenum Content | 0.45–0.65% |
| Delivery Condition | AR, N, N+T (subject to specification and customer requirements) |
| Thickness | 6–250 mm |
| Width | 1,000–4,000 mm |
| Length | 3,000–18,000 mm |
| Inspection Standards | EN 10204 3.1 / 3.2, UT Testing (EN 10160, ASTM A578/A578M), PMI (Optional), Third-Party Inspection |
| Available Processing | CNC Cutting, Beveling, Drilling, Milling, Flame Cutting, Edge Preparation |
The Chemical Composition of ASME SA387 Gr.11 Steel Plate
| Element | Chemical Composition (%) | |
| SA387 Grade 11 | ||
| Carbon: | Heat Analysis: | 0.05 - 0.17 |
| Product Analysis: | 0.04 - 0.17 | |
| Manganese: | Heat Analysis: | 0.40 - 0.65 |
| Product Analysis: | 0.35 - 0.73 | |
| Phosphorus: | Heat Analysis: | 0.035 |
| Product Analysis: | 0.035 | |
| Sulphur (max): | Heat Analysis: | 0.035 |
| Product Analysis: | 0.035 | |
| Silicon: | Heat Analysis: | 0.50 - 0.80 |
| Product Analysis: | 0.44 - 0.86 | |
| Chromium: | Heat Analysis: | 1.00 - 1.50 |
| Product Analysis: | 0.94 - 1.56 | |
| Molybdenum: | Heat Analysis: | 0.45 - 0.65 |
| Product Analysis: | 0.45 - 0.70 |
The Mechanical Property of ASME SA387 Gr.11 Steel Plate
| 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 |
| Reduction of area in % | - | - |
ASME SA387 Gr.11 Heat Treatment Objectives
1
Enhance the toughness of the steel to prevent brittle failure.
2
Achieve a balance between hardness and toughness
3
Improve tensile strength, yield strength, and elongation.
The High Temperature Properties of ASME SA387 Gr.11 Steel Plate
Continuous Long-Term Service Temperature Range: 350°C to 480°C
Short-Term Peak Allowable Temperature Limit: ≤ 510°C
Vs SA516 Gr.70 Carbon Steel: At 450°C, the creep resistance of SA387 Gr. 11 is more than 3 times greater than that of SA516 Gr. 70. Conventional carbon steel exhibits pronounced creep deformation once temperatures exceed 400°C.
Vs SA387 Gr.12: Within the 400°C to 480°C range, SA387 Gr. 11 provides 15% to 20% higher creep-rupture strength. In comparison, SA387 Gr. 12 is typically limited to applications below 420°C.
High-Temperature Oxidation Resistance (450°C+):
- Protective Passive Film: Forms a dense chromium oxide Cr2O3 surface layer that effectively isolates the base metal from ambient air and high-temperature oxidizing media.
- Limitations of Alternative Grades: Conventional carbon steel lacks chromium protection, leading to a loose, easily spalled oxide layer at 450°C and above. SA387 Gr. 12 features lower chromium content, which reduces the long-term thermal stability of its protective scale.
- Continuous Performance: SA387 Gr. 11 maintains continuous and stable oxidation resistance across the entire 350°C to 480°C operating temperature range.
Resistance to Hydrogen Embrittlement and High-Temperature Hydrogen Attack (HTHA):
- Microstructural Stabilization: Molybdenum (Mo) segregates to and stabilizes the grain boundaries, effectively inhibiting the permeation and accumulation of atomic hydrogen.
- Immunity to Cracking Mechanisms: Outperforms lower grades by showing no susceptibility to Hydrogen-Induced Cracking (HIC) or Sulfide Stress Cracking (SSC) in moderate-to-high-temperature, high-pressure hydrogen service environments.
4. High-Temperature Impact Toughness Performance
Standard Mandatory Impact Verification:
- Class 2: Charpy V-notch impact energy ≥ 27 J at -29°C.
- Class 1: Evaluated and certified in accordance with the mandatory ASME impact testing criteria.
Moderate-to-High-Temperature Toughness Stability (350°C to 480°C):
- Exhibits no pronounced toughness degradation or high-temperature embrittlement phenomena.
- Maintains a stable internal microstructure, ensuring impact energy values remain consistent over extended exposure.
- Eliminates the risk of brittle fracture under operational thermal shocks, cyclic start-ups/shutdowns, and fluctuating load conditions.
- Unlike conventional low-alloy steels, it resists toughness attenuation and subsequent catastrophic brittle failure induced by long-term high-temperature service.
The Main Applications of ASME SA387 Gr.11 Steel Plate
Petrochemical
Hydrocrackers
Reactors
Fractionators
Heat exchangers
Separator vessels
Boiler drums
Steam piping
Superheater headers
Pressure vessels
High-temperature process equipment
Why Choose GNEE Steel?
Full-batch inspection: Chemical/spectroscopic analysis, tensile testing, impact testing, hardness testing, and ultrasonic flaw detection.
Complete Mill Test Certificates (MTC) provided with every shipment; third-party independent inspection (SGS, BV) supported.
Custom processing: Flame/plasma/laser cutting, CNC rolling, bending, edge planing, and drilling.
Technical support: Free material selection, consultation on high-temperature performance parameters, and guidance on welding and heat treatment procedures.
Global logistics: Seaworthy anti-rust packaging, door-to-door delivery, and full support with customs clearance documentation.
Flexible supply: Stock available for small-batch trial orders; custom production for large-volume, long-term orders.
Need a quotation within 24 hours? Send your required grade, dimensions, quantity, and destination port-GNEE Steel will provide a competitive offer together with available stock and delivery options.
FAQ
Q: What are the equivalent steel grades for ASME SA387 Gr. 11?
A: ASME SA387 Gr. 11 is a chromium-molybdenum alloy pressure vessel steel. Its primary international equivalents include EN 10028 13CrMoSi5-5 (Europe) and BS 621B (British Standard). In the US, it is mirrored by the ASTM A387 Gr. 11 specification.
Q: In engineering design, can ASME SA387 Gr. 11 be substituted for Gr. 12 or Gr. 22?
A: No. In ASME engineering design, you generally cannot directly substitute SA387 Gr. 11 for Gr. 12 or Gr. 22. While they are all chrome-molybdenum alloy steels used for pressure vessels, they differ significantly in chemical composition, mechanical properties, and maximum allowable design temperatures.
Q: What are the key differences in alloy composition among ASME SA387 Gr. 11, Gr. 12, Gr. 22, and Gr. 91?
A: ASME SA387 Gr. 11, 12, 22, and 91 are chromium-molybdenum ("chrome-moly") alloy steels tailored for elevated temperatures. Their primary differences lie in chromium and molybdenum percentages, which dictate their specific creep resistance, tensile strength, and maximum operating temperature thresholds.
