SA 387 Gr. 11 Cl. 2 is an ASME/ASTM chromium-molybdenum alloy steel for high-temperature pressure vessels, offering superior oxidation/corrosion resistance due to its chromium content, with enhanced mechanical strength (higher tensile/yield) and good weldability, used in oil & gas, petrochemicals, and power generation for boilers, tanks, and pipes.ASME SA 335 Gr. 11 CL 2 Alloy Steel Plates are suitable for bending, flanging, and similar forming operations, and for fusion welding. However, these products are tested rigorously by our highly qualified team using different techniques namely, transverse or longitudinal tension test, flattening test, and hardness or bend test etc.
SA387 Gr 11 CL 2 Steel Plate Chemical Composition
| C | Mn | P | S | Si | Cr | Mo |
| 0.04 - 0.17 | 0.35 - 0.73 | 0.035 | 0.035 | x 0.44 - 0.86 | 0.94 - 1.56 | 0.40 - 0.7 |
SA387 Grade 11 Class 2 Plate Mechanical Properties
| A387 / SA387 Grade 11 | Class 2 | |
| Tensile Strength (ksi) | 70-90 | |
| Tensile Strength (MPa) | 485-620 | |
| Yield Strength (ksi) | 45 | |
| Yield Strength (MPa) | 310 | |
| Elongation in 50mm (%) | 18 | |
| Elongation in 50mm (%) | 22 |
Detailed Process Flow：
Raw Material Preparation and Steel Melting:
Scrap steel, ferroalloys (including chromium and molybdenum), and hot metal are charged into an electric arc furnace (EAF) or induction furnace in predetermined proportions for melting.Refining processes such as LF, VD, or VOD are applied to remove impurities and adjust the chemical composition. The aim is to ensure that chromium (1.00–1.25%) and molybdenum (0.40–0.60%) meet the required ranges, while controlling harmful elements such as sulfur and phosphorus.
Continuous Casting / Slab Making:
The molten steel is cast into continuous cast slabs, which are then cut to the required length. Alternatively, ingots may be cast and subsequently rolled into slabs.
Hot Rolling:
Slabs are heated to the rolling temperature (approximately 1000–1200°C) and repeatedly rolled in a rolling mill to achieve the desired thickness and width of the finished plate.
Heat Treatment – Critical Steps:
Normalizing: The steel plate is air-cooled to refine the grain structure and improve the microstructure.Quenching (optional, but important for Class 2): The plate is rapidly cooled (water-cooled or air-cooled) to obtain a martensitic structure.Tempering (performed after normalizing or quenching): The plate is reheated to a specific temperature (e.g., 600–700°C), held for a certain period, and then air-cooled. This step relieves internal stress, produces a tempered sorbite structure, and enhances toughness.
Finishing and Inspection:
Trimming and leveling: Removal of scale and ensuring the plate is flat.Ultrasonic testing (UT): Detection of internal defects.Tensile, impact, and hardness tests: Verification that mechanical properties meet standards (e.g., yield strength, tensile strength, impact energy).Chemical composition analysis: Confirmation of element contents.Marking and painting.
applications
Oil & Gas Industry (Refining & Extraction):
In 2026, as global extraction shifts toward more complex reservoirs, this alloy is the primary choice for hydrocracking units, desulfurization reactors, and fractionation columns. Its 1.25% Chromium content provides vital resistance to hydrogen attack and Hydrogen-Induced Cracking (HIC), making it indispensable for processing high-temperature hydrocarbons and "sour gas" (H2S-rich environments) where structural integrity is non-negotiable.
Petrochemical and Chemical Processing:
The material is extensively used in the fabrication of catalytic reformers, synthesis towers, and high-pressure reaction vessels. Petrochemical plants operating in 2026 require equipment that can withstand both aggressive chemical corrosion and extreme internal pressures. The Class 2 designation provides the high tensile strength necessary to resist shell fatigue and chemical degradation during continuous, multi-year production cycles.
Power Generation (Thermal and Nuclear):
In modern power facilities, SA 387 Gr.11 Cl.2 is utilized for superheater headers, steam drum components, and main steam piping. It is engineered to maintain high yield strength under the intense steam cycles of supercritical power plants. Its thermal stability ensures that critical components in both fossil fuel and nuclear energy sectors remain safe from brittle fracture during rapid temperature fluctuations.
Industrial Boilers and Heat Exchangers:
This alloy is specifically designed for environments where oxidation and creep resistance are critical. It is the standard for heat exchanger shells and boiler internal structures that operate at temperatures exceeding 500 C .By preventing "creep" (the slow plastic deformation of metal under stress), it ensures that energy-conversion equipment maintains its dimensional accuracy and safety over decades of service.
If you have project requirements for SA387 Gr 11 CL 2, we welcome your inquiry. GNEE maintains a large inventory of commonly used high strength steel grades for your selection.For detailed mechanical properties, chemical composition, and technical data, as well as free samples, please contact our factory immediately. We offer competitive prices, stable quality, and professional service. Email:beam@gneesteelgroup.com.
Is SA 387 Grade 11 Class 2 suitable for welding?
Yes, it has good weldability, but due to its Cr-Mo composition, preheating and post-weld heat treatment (PWHT) are generally recommended. Proper welding procedures help prevent cold cracking and ensure that the weld joint maintains the required strength and toughness.
What preheat and PWHT temperatures are typical for SA 387 Grade 11 Class 2?
Preheat temperatures typically range from 200–300°C, depending on plate thickness and welding consumables. PWHT is usually performed at 620–680°C to relieve residual stresses and improve the toughness of the weld and heat-affected zone (HAZ).
What types of pressure vessels use SA 387 Grade 11 Class 2?It is used in a variety of pressure vessels, including boilers, heat exchangers, reactors, reformers, and hydrogenation units. It is particularly suitable for equipment operating at high temperatures and pressures where creep resistance and hydrogen attack resistance are essential.
In which industries is SA 387 Grade 11 Class 2 commonly used?
It is widely used in the oil and gas industry, petrochemical plants, chemical processing facilities, and power generation plants. It is also found in refineries, where it is used for equipment handling high-temperature hydrocarbons and hydrogen-rich fluids.
Can SA 387 Grade 11 Class 2 be used in hydrogen service?
Yes, its Cr-Mo composition provides good resistance to hydrogen attack at elevated temperatures, making it suitable for hydrogenation reactors, reformers, and other equipment in hydrogen-rich environments. However, service conditions such as temperature, pressure, and hydrogen partial pressure must be considered to ensure long-term reliability.
What thickness range is SA 387 Grade 11 Class 2 available in?
It is commonly produced in thicknesses from 6 mm up to 150 mm or more, depending on the manufacturer's capabilities and customer specifications. Thicker plates may require additional heat treatment or testing to ensure mechanical properties are maintained through the cross-section.
What non-destructive testing (NDT) is typically applied to SA 387 Grade 11 Class 2 plates?
Common NDT methods include ultrasonic testing (UT) for internal defects, radiographic testing (RT) for weld inspections, magnetic particle inspection (MPI) for surface cracks, and liquid penetrant inspection (LPI) for detecting surface discontinuities. The specific tests are usually specified in the purchase order and must comply with ASME and other applicable standards.
What are the differences in mechanical properties between SA 387 Grade 11 Class 2 and carbon steel plates like SA 516 Grade 70?
SA 387 Grade 11 Class 2 has higher strength at elevated temperatures and better resistance to hydrogen attack than SA 516 Grade 70. While SA 516 Grade 70 is suitable for low-to-moderate temperature service, Grade 11 Class 2 is preferred for high-temperature pressure vessels due to its Cr-Mo alloying.
How does the weldability of SA 387 Grade 11 Class 2 compare to that of SA 387 Grade 22?
Both grades are weldable, but SA 387 Grade 11 Class 2 generally requires lower preheat and post-weld heat treatment (PWHT) temperatures than Grade 22. Grade 22's higher alloy content increases hardenability, making it more susceptible to cold cracking if proper welding procedures are not followed.