SA 387 Gr.11 Cl.1 is an ASME/ASTM chromium-molybdenum alloy steel plate designed for welded boilers and pressure vessels in elevated temperature service, featuring moderate strength from a normalized heat treatment (Class 1) and a composition of roughly 1.25% Chromium and 0.5% Molybdenum, ideal for chemical, petrochemical, and power generation industries requiring good heat resistance and ductility.
Equivalents
| BS | EN | ASTM/ASME | DIN |
| 621 B | ––– | SA387-11-1 | ––– |
Specifications for ASME SA387 Grade 11 Alloy Steel Plates
| Designation | Nominal Chromium Content (%) |
Nominal Molybdenum Content (%) |
| SA387 Grade 11 | 1.25% | 0.50% |
Tensile Requirements for ASME SA387 Grade 11 Alloy Steel Plates Class 1 Plates
| Designation: | Requirement: | Grade 11 |
| SA387 Grade 11 | Tensile strength, ksi [MPa] | 75 to 100 [515 to 690] |
| Yield strength, min, ksi [MPa]/(0.2% offset) | 43 [310] | |
| Elongation in 8 in. [200mm], min % | 18 | |
| Elongation in 2 in. [50mm], min, % | 22 | |
| Reduction of area, min % | ––– |
Chemical Requirements for ASME SA387 Grade 11 Alloy Steel Plates
| 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 |
Key Process Elements:
The material is a chromium‑molybdenum alloy steel plate under ASME SA‑387, designed for high‑temperature and high‑pressure service. Its alloying system, primarily chromium and molybdenum, forms a stable microstructure at elevated temperatures, ensuring good strength and creep resistance.
Grade Interpretation:
SA indicates compliance with ASTM/ASME standards; 387 is the standard number for this type of Cr‑Mo steel; Gr.11 means the material contains approximately 1.25% chromium and 0.5% molybdenum, with chemical compositions strictly meeting standard requirements; Cl.1 (Class 1) specifies the first level of mechanical properties and heat treatment, typically normalizing followed by
tempering, to achieve good toughness and high‑temperature stability.
Manufacturing Process:
Steelmaking usually adopts basic oxygen furnace or electric arc furnace, with strict control of sulfur
and phosphorus to improve purity. Controlled rolling ensures uniform thickness and refines the
microstructure. Heat treatment is the key step: normalizing homogenizes the structure, and
tempering reduces hardness while enhancing toughness, thus ensuring long‑term performance
at high temperatures. Inspection includes ultrasonic testing (UT) and penetrant testing (PT) to
detect internal and surface defects.
Key Applications
Oil & Gas:
SA‑387 Gr.11 steel is widely used in equipment for processing, transporting, and storing oil and gas, especially in high‑temperature and high‑pressure conditions. It is particularly suitable for sour service environments containing hydrogen sulfide (H₂S), where resistance to sulfide stress cracking and creep is essential. This material is commonly found in refinery columns, separators, and pressure vessels.
Petrochemical Plants:
In petrochemical facilities, SA‑387 Gr.11 is used for reactors, distillation towers, heat exchangers, and critical piping systems that operate at elevated temperatures. Its ability to maintain strength and toughness under prolonged thermal stress makes it ideal for processes such as cracking, reforming, and hydroprocessing.
Power Generation:
The material is extensively employed in thermal power plants for boilers, superheaters, headers, and heat exchangers. Its excellent high‑temperature strength and creep resistance ensure reliable performance in steam systems operating at high pressures and temperatures.
Chemical Plants:
SA‑387 Gr.11 is used in a variety of chemical processing equipment, including reactors, storage tanks, and transfer lines, where resistance to high temperatures and corrosive media is required. Its chromium‑molybdenum composition provides good stability and durability in aggressive chemical environments.
Get an valued quotation for SA 387 Gr.11 Cl.1, Contact GNEE Steel.
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.
Does SA387 GR 11 CLASS 1 have good corrosion resistance?
It has moderate corrosion resistance, especially resistance to hydrogen attack, suitable for harsh process environments in petrochemical industries.
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.
What is the difference in high-temperature ductility between SA387 GR 11 CLASS 1 and SA387 GR 91?
GR 91 has higher chromium content and better high-temperature ductility, while GR 11 CLASS 1 is more cost-efficient for medium-high temperature applications.
Can SA387 GR 11 CLASS 1 be used to manufacture heat exchanger components?
Yes, its excellent heat transfer characteristics and thermal fatigue resistance make it suitable for heat exchanger plates and tubes.
What inspection methods are required for SA387 GR 11 CLASS 1 after heat treatment?
It requires mechanical property testing (tensile, impact), microstructure inspection, and non-destructive testing (ultrasonic, radiographic) to meet ASME standards.
Is SA387 GR 11 CLASS 1 suitable for manufacturing high-temperature piping flanges?
Yes, it can withstand thermal cycling and mechanical stress, ensuring leak-tight connections in high-temperature and high-pressure piping systems.
What precautions should be taken when welding SA387 GR 11 CLASS 1?
Preheating before welding and post-weld heat treatment are necessary to prevent weld cracks and maintain the material's mechanical properties.