A387 Grade 11 Class 2 for boiler

1.What are the chemicai composition of A387 Grade 11 Class 2?

2.What is the difference between A387 Grade 11 Class 2 and SA387 Grade 11 Class 2?

The key difference between A387 Grade 11 Class 2 and SA387 Grade 11 Class 2 lies in their standardization context and application scope

Standardization and Certification

• A387: Published by ASTM International, this is a voluntary standard for general industrial use. Compliance is self-certified, with no mandatory third-party oversight .
• SA387: Adopted byASME (American Society of Mechanical Engineers), this standard is mandatory for pressure vessel applications under ASME BPVC (Boiler and Pressure Vessel Code). Compliance requires rigorous third-party inspection, traceability documentation, and adherence to ASME’s supplementary requirements.

Application Scope

• A387: Suited for non-code-critical applications (e.g., general-purpose heat exchangers) where cost efficiency and flexibility are priorities .
• SA387: Required for ASME-compliant pressure vessels, boilers, and pipelines in regulated industries (e.g., oil/gas, power generation), ensuring structural integrity under extreme conditions .

3.What are the characteristic advantages of A 387 Grade 11 Class 2?

 Excellent High-Temperature Performance

• Creep and Oxidation Resistance: The 1.25% chromium (Cr) and 0.5% molybdenum (Mo) content provides robust resistance to creep deformation and oxidation at elevated temperatures (up to ~595°C / 1100°F) . This makes it suitable for components exposed to prolonged high-temperature stress, such as steam pipes, pressure vessels, and reactors.
• Stable Microstructure: The Q&T heat treatment produces a fine-grained tempered martensitic/bainitic structure, enhancing long-term strength and dimensional stability under thermal cycling .

Good Weldability and Formability

• Weldability: The balanced Cr-Mo alloy content (low carbon equivalent, CE) allows for reliable welding without excessive preheating or post-weld heat treatment (PWHT), though PWHT is often recommended for thick sections to reduce residual stress .
• Formability: Despite its high strength, the steel maintains ductility (elongation ≥18%) and toughness, enabling cold or hot forming into complex shapes like heads, nozzles, or curved sections .

Enhanced Corrosion Resistance

• Hydrogen and Sulfide Resistance: The Cr-Mo alloy system resists hydrogen-induced corrosion and sulfidation in high-temperature, high-pressure hydrogen or sulfur-containing environments .
• General Corrosion Resistance: Chromium improves resistance to atmospheric and water-based corrosion compared to carbon steels .

4.What is A 387 Grade 11 Class 2 equivalent to?

A 387 Grade 11 Class 2 (ASTM A387/A387M) is a 1.25Cr-0.5Mo alloy steel plate primarily used for high-temperature pressure vessel applications. Its equivalents in other international standards are as follows:  ASME SA387 Grade 11 Class 2, EN 10028-2 13CrMo4-5 , EN 10CrMo910, JIS G4109 SCMV3-1/SCMV3-2, GB 713 15CrMoR