SA 387 Gr 11 Cl 1 refers to an ASME/ASTM alloy steel plate specification for chromium-molybdenum steel used in high-temperature pressure vessels and boilers, featuring around 1.25% Chromium (Cr) and 0.5% Molybdenum (Mo) for enhanced strength, heat resistance, and oxidation resistance, with Class 1 indicating a specific lower tensile strength level compared to Class 2.
SA387 GR 11 CLASS 1 Plate Specification :
Width: 1000mm-4500mm
Thickness: 5mm to 150mm
Length: 3000mm-18000mm
Supply Condition : As Rolled, Normalized Rolling, Furnace Normalizing, Vacuum Degassing, Simulated Post-Weld Heat Treatment or as per customer requirement.
Impact tested: -52° C
Process of Manufacturing: Hot-Rolled (HR)
ASTM SA387 GR 11 CL. 1 Chemical Composition :
| C | Mn | P | S | Si | Cr | Mo |
| 0.04 - 0.17 | 0.35 - 0.73 | 0.035 | 0.035 | 0.44 - 0.86 | 0.94 - 1.56 | 0.40 - 0.7 |
ASME SA387 GR. 11 CL. 1 Mechanical Properties :
| Grade | Thickness | Yield strength | Tensile strength | Elongation in 2" 1) (min %) |
Elongation in 8" 1) (min %) |
|---|---|---|---|---|---|
| Grade 11 Class 1 | 0.185 - 3.60 4.70 - 91.4 |
35 | 60 - 85 | 22 |
19 |
Key Processing Steps:
Heat Treatment:
Normalization: Heat the steel plate to a specified temperature (typically above the critical temperature), hold for a suitable period, and then cool in air to refine the grain size and homogenize the microstructure.
Quenching: Heat the steel plate to the quenching temperature and then cool rapidly (usually in oil or water) to form a martensitic structure and increase hardness.
Tempering: After quenching, reheat the steel to a lower temperature, hold for a certain time, and then cool to relieve internal stresses, improve toughness, and achieve the required combination of properties.
applications
Pressure vessels
SA 387 Gr 11 Cl 1 is widely used in the fabrication of pressure vessels for oil refineries, chemical plants, and power generation facilities. Its excellent creep resistance and high-temperature strength make it suitable for handling corrosive fluids and gases under elevated pressures and temperatures.
Tubing
This grade of steel is employed in the production of high-temperature tubing for boilers, heat recovery systems, and petrochemical processing units. Its good weldability and resistance to oxidation allow it to maintain structural integrity and dimensional stability in continuous high-heat service environments.
Flanges
SA 387 Gr 11 Cl 1 is commonly specified for flanges used in high-pressure and high-temperature piping systems. Its ability to withstand thermal cycling and mechanical stress ensures leak-tight connections in critical applications such as refinery headers and power plant steam lines.
Piping
It is extensively used in the construction of process piping for oil, gas, and chemical industries. The steel's combination of strength, toughness, and resistance to hydrogen attack makes it ideal for transporting hot fluids and gases over long distances in harsh operating conditions.
Heat exchangers
Plates and tubes made from SA 387 Gr 11 Cl 1 are utilized in shell-and-tube heat exchangers, reboilers, and condensers. Its superior heat transfer characteristics and resistance to thermal fatigue enable efficient energy exchange in high-temperature process streams.
High-temperature ducting
This steel grade is used for fabricating high-temperature ducting in power plants, incinerators, and industrial furnaces. Its ability to resist deformation and oxidation at elevated temperatures ensures reliable performance in conveying hot flue gases and combustion products.
Pipe clamps
SA 387 Gr 11 Cl 1 is often chosen for manufacturing heavy-duty pipe clamps and supports in high-temperature piping systems. Its high strength and creep resistance help maintain proper alignment and prevent sagging or failure of pipes under sustained thermal and mechanical loads.
Valves
Components such as valve bodies, bonnets, and trim parts are frequently made from SA 387 Gr 11 Cl 1. Its toughness, corrosion resistance, and ability to withstand high pressures and temperatures make it suitable for critical control and isolation valves in oil, gas, and power applications.
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What is the main material category of SA387 GR 11 CLASS 1?
It is a low-alloy chromium-molybdenum (Cr-Mo) steel plate, primarily used for high-temperature and high-pressure applications.
What core mechanical properties does SA387 GR 11 CLASS 1 possess after heat treatment?
It has excellent high-temperature strength, toughness, creep resistance, and good weldability, with reduced internal stress.
Which heat treatment processes are commonly used for SA387 GR 11 CLASS 1?
Normalizing + Tempering or Quenching + Tempering, to refine microstructure and optimize mechanical performance.
What is the critical temperature range for normalizing SA387 GR 11 CLASS 1?
It is typically heated above the critical temperature (around 890-920°C) before air cooling.
Which standard governs the production and inspection of SA387 GR 11 CLASS 1?
It complies with the ASME SA-387 standard, a specification for pressure vessel plates for high-temperature service.
What is the primary application of SA387 GR 11 CLASS 1?
It is mainly used to manufacture components of high-temperature and high-pressure equipment, such as boilers and pressure vessels.
What is the difference in microstructure between SA387 GR 11 CLASS 1 after quenching and after tempering?
Quenching forms hard martensite, while tempering transforms it into tempered martensite, relieving internal stress and improving toughness.
How does SA387 GR 11 CLASS 1 compare to stainless steel in terms of cost and application scope?
It is more cost-effective than stainless steel, suitable for Cr-Mo compatible high-temperature environments, while stainless steel is preferred for strong corrosion resistance needs.