Gnee Steel ensures ASTM A387 Grade 11 steel plates meet the highest quality standards through chemical, mechanical, and non-destructive testing. Learn about our inspection process for pressure vessels and high-temperature applications.
Overview of ASTM A387 Grade 11 Steel Testing
ASTM A387 Grade 11 is a chromium-molybdenum (Cr-Mo) alloy steel designed for welded boilers and pressure vessels in elevated temperature service.
ASTM A387 Grade 11 steel plates
Due to its critical application in the petrochemical, power, and industrial sectors, rigorous testing and inspection are essential to ensure mechanical strength, corrosion resistance, and dimensional accuracy.
At Gnee Steel, every batch of A387 GR.11 steel plate undergoes comprehensive testing, from raw material analysis to final delivery, ensuring full compliance with ASTM A387 / ASME SA387 standards.
Chemical Composition of A387 Grade 11 Steel
| Grade / Material | C | Mn | Si | P | S | Cr | Mo |
|---|---|---|---|---|---|---|---|
| A387 Grade 11 Class 2 | 0.05-0.17 | 0.40-0.65 | 0.15-0.40 | 0.035 | 0.035 | 1.00-1.50 | 0.45-0.65 |
Mechanical Properties of A387 Grade 11 Steel
| Grade / Material | Tensile Strength (Ksi / MPa) | Yield Strength (Ksi / MPa) | Elongation (%) |
|---|---|---|---|
| A387 Grade 11 Class 2 | 75-100 / 515-690 | 45 / 310 | 18 |
Mechanical Property Testing of A387 Grade 11 plates
To confirm mechanical performance, A387 Grade 11 plates are tested for:
Tensile Strength: 415–585 MPa (Class 1) / 515–690 MPa (Class 2)
Yield Strength: 240 MPa (Class 1) / 310 MPa (Class 2)
Elongation: 19–22% depending on class
Impact Toughness: Optional, as required for pressure vessel applications
Testing Methods:
Universal Testing Machine (UTM) for tensile and yield strength
Charpy impact test for toughness
Hardness testing using Rockwell or Brinell method
Non-Destructive Testing of A387 Grade 11 plates
- Gnee Steel applies strict NDT inspections to ensure defect-free plates suitable for pressure vessel construction:
- Radiographic Testing (X-Ray / Gamma Ray): Detects internal defects such as cracks, voids, and inclusions.
- Ultrasonic Testing (UT): Ensures plate thickness uniformity and identifies internal flaws.
- Magnetic Particle Inspection (MPI): Detects surface and near-surface cracks.
- Hydrostatic Pressure Testing: Confirms the steel's ability to withstand operational pressures.
Dimensional & Surface Inspection of A387 Grade 11 plates
- Thickness, width, and length measurement: Tolerance within ±1/16" or per customer requirement.
- Surface finish inspection: Hot-rolled, cold-rolled, or coated plates checked for smoothness, burrs, and scaling.
- Flatness and straightness: Ensures proper assembly in welded boilers and pressure vessels.
Certification & Quality Assurance of A387 Grade 11 plates
Every A387 GR.11 steel plate comes with:
- Mill Test Certificate (MTC EN 10204 3.1 / 3.2)
- Third-party inspection reports from certified agencies
- NACE MR0175 compliance for sour service
- Optional HIC (Hydrogen Induced Cracking) testing
This guarantees high-quality plates, traceable from raw material to finished product, ready for critical applications in power, petrochemical, and industrial plants.
ASTM A387 Grade 11 steel plates are engineered for high-performance, corrosion resistance, and long-term durability. Through comprehensive chemical, mechanical, and non-destructive testing, Gnee Steel ensures that every plate delivered meets strict international standards, making it ideal for pressure vessels, boilers, and high-temperature service applications.
➡ Contact Gnee Steel today to request certified A387 Grade 11 plates with full inspection reports.
Contact Gnee Steel today to request certified A387 Grade 11 plates
What is ASTM A387 material?
ASTM A387 GR. 91 CL. 2 Alloy Steel Plates manufactured at the world's finest steel mills, this molybdenum-chrome based alloy has excellent resistance to greater working temperatures, making it the right selection for various applications like in gas, oil, chemical, and power generation.
What is ASTM A387 Grade 11 equivalent to?
ASTM A387 grade 11 equivalent steel is ASME SA387 grade 11. ASTM A387 grade 11 covers A387 grade 11 class 1 and A387 grade 11 class 2, which are equivalent to ASME SA387 grade 11 class 1 and SA387 grade 11 class 2 respectively.
What is the difference between ASTM A182 and A387?
A387 is Plate material. A182 is Forging material. You can refer relevant ASTM Book of standards.
What is ASTM A387?
The ASTM A387 specification is the Standard Specification for Pressure Vessel Plates, Alloy Steel, Chromium-Molybdenum plates used in the application of welded boilers and pressure vessels subjected to elevated temperatures. The two grades SSAB produces are available as Class 1 and/or Class 2.