SA 387 GR 91 CL 1 / CL 2 – High-Performance Chromium-Molybdenum-Vanadium Steel for Extreme Heat and Pressure SA 387 Grade 91 Class 1 and Class 2 are high-strength alloy steel plates engineered for high-temperature, high-pressure service. As part of the 9Cr-1Mo-V (Chromium-Molybdenum-Vanadium) family, these plates are quenched and tempered to deliver exceptional creep strength, thermal stability, and oxidation resistance. Compliant with ASME and ASTM standards, SA 387 GR 91 CL 1/2 is a material of choice in power plants, petrochemical processing, and thermal systems, especially where long-term reliability under elevated temperatures is essential. Key Highlights: High-Temperature Performance: Designed for use in environments exceeding 600°C (1112°F), offering excellent creep resistance under sustained load and heat. Alloyed with Chromium (9%), Molybdenum (1%), and Vanadium: Ensures improved oxidation resistance, hardness retention, and structural strength at high temperatures. Two Class Options: Class 1: Slightly lower tensile strength; optimized for standard elevated pressure vessels. Class 2: Higher tensile strength; preferred in extreme temperature-pressure applications. Excellent Weldability and Fabrication: Weldable with proper preheat and post-weld heat treatment; suitable for forming and machining with careful control. Mechanical Properties Overview: Property SA 387 Gr 91 Cl 1 SA 387 Gr 91 Cl 2 Yield Strength ≥ 310 MPa ≥ 415 MPa Tensile Strength 585–760 MPa 620–795 MPa Elongation ≥ 20% ≥ 18% Temperature Resistance Up to ~650–675°C (1200–1250°F) Up to ~650–675°C (1200–1250°F) Typical Applications: Supercritical and Ultra-Supercritical Boilers: Headers, steam lines, and pressure-retaining parts in thermal power stations. Refineries and Petrochemical Plants: High-pressure reactors, heat exchangers, and furnace components exposed to thermal cycling and hydrogen attack. Nuclear and Fossil Fuel Power Generation: Components requiring long service life and strength at elevated temperatures. Oil & Gas Industry Equipment: Pressure vessels and piping in sour gas service or hydrogen-rich environments. Conclusion: SA 387 GR 91 CL 1/2 is one of the most advanced alloy steel plates available for critical applications requiring unmatched strength, creep resistance, and thermal endurance. With its robust alloy composition and proven performance in extreme service conditions, it stands as a trusted material for next-generation thermal and power system designs.