A387 Grade 12 Class 1 is a chromium-molybdenum alloy steel plate covered by the ASTM A387 standard, commonly used in welded boilers and pressure vessels that operate at elevated temperatures. It is part of the family of low-alloy steels where chromium and molybdenum are added to enhance creep strength, oxidation resistance, and overall durability under high-temperature conditions. The designation "Grade 12" identifies the specific alloy composition, while "Class 1" indicates that the material is supplied in the normalized and tempered condition, which provides a good combination of strength and toughness suitable for many high-pressure applications in the oil, gas, and power generation industries. This grade is often selected when equipment must withstand prolonged exposure to heat without significant loss of mechanical properties.
ASTM A387 Alloy Steel Grade 12 Cl 1 Plates Equivalent Grades
| BS | EN | ASTM/ASME | UNS | DIN |
| – | – | A387 / SA 387 | K11757 | – |
ASTM A387 Alloy Steel GR 12 Cl 1 Plates Chemical Composition
| Grade | C | Mn | P | S | Si | Cr | Mo |
| ASTM A387 Gr 12 | 0.04 – 0.17 | 0.35 – 0.73 | 0.035 | 0.035 | 0.13 – 0.45 | 0.74 – 1.21 | 0.4 – 0.65 |
ASTM A387 Alloy Steel GR 12 Cl 1 Plates Mechanical Properties
| A387 Grade 12 | Class 1 |
| Tensile Strength (ksi) | 50-80 |
| Tensile Strength (MPa) | 380-550 |
| Yield Strength (ksi) | 33 |
| Yield Strength (MPa) | 230 |
| Elongation in 200mm (%) | 18 |
| Elongation in 50mm (%) | 22 |
| Reduction of area in % | – |
processing
1. Steelmaking and Refining
Melting: Primary melting is conducted in an Electric Arc Furnace (EAF) or Basic Oxygen Furnace (BOF).
Ladle Refining (LRF): The chemical composition is precisely adjusted to meet ASTM standards, specifically adding approximately 1.00% Chromium (Cr) and 0.50% Molybdenum (Mo).
Vacuum Degassing (VD): This step removes harmful gases like hydrogen and oxygen to ensure high internal purity and reduce the risk of hydrogen-induced cracking.
2. Rolling and Forming
Casting: The molten steel is cast into slabs via continuous casting or ingot casting.
Hot Rolling: Slabs are reheated and rolled through multiple passes to achieve the target thickness (ranging from 6mm to 300mm).
3. Heat Treatment (Critical for Class 1)
To meet the mechanical properties of Class 1 (which features lower tensile strength but higher ductility compared to Class 2), the plates undergo specific thermal cycles:
Normalizing: Heating the steel to a temperature above its critical range and cooling in air to refine the grain structure.
Tempering: Heating to a sub-critical temperature (minimum 1150°F / 620°C) to relieve stresses and achieve the required yield strength (min 275 MPa) and tensile strength (450–585 MPa).
4. Inspection and Testing
Chemical Analysis: Verification of Cr, Mo, C, Si, Mn, and P/S levels.
Mechanical Testing: Includes Tensile Tests, Yield Strength Tests, and Elongation measurements.
Non-Destructive Testing (NDT): Ultrasonic Testing (UT) is performed per ASTM A435 or A578 to ensure internal integrity.
Surface Preparation: Shot blasting and marking the plate with the grade, class, and heat number for traceability.
Key Industrial Applications
Oil and Gas Refining:
Primarily used in "sour service" environments where resistance to hydrogen-induced cracking and sulfidation is required.
Petrochemical Processing:
Ideal for fabricating chemical reactors, process vessels, and storage tanks handling corrosive media.
Power Generation:
Used in the construction of boiler drums, steam pipelines, and thermal power plant components subjected to sustained heat.
Heat Transfer Equipment:
Frequently specified for shell-and-tube heat exchangers and reheaters due to its efficient heat transfer properties and mechanical stability.
Why Choose Us :
You can get the perfect material according to your requirement at the least possible price.
We also offer Reworks, FOB, CFR, CIF, and door to door delivery prices. We suggest you to do deal for shipping which will be quite economical.
The materials we provide are completely verifiable, right from raw material test certificate to the final dimensional statement.(Reports will show on requirement)
We guarantee to give a response within 24hours(usually in the same hour)
You can get stock alternatives, mill deliveries with minimizing manufacturing time.
We are fully dedicated to our customers. If it will not possible to meet your requirements after examining all options, we will not mislead you by making false promises which will create good customer relations.
If you want to learn more about A387 Grade 12 Class 1 GNEE's products, you can send an email to beam@gneesteelgroup.com. We are more than happy to assist you.
What are the common welding consumables used with ASTM A387 Grade 12 Class 1?
Common welding consumables for ASTM A387 Grade 12 Class 1 include E8018-B2 electrodes for SMAW and ER80S-B2 wires for GMAW/FCAW. These consumables have matching chromium and molybdenum contents to ensure good weld metal strength and creep resistance at elevated temperatures. For SAW, F8P2-B2 fluxes and corresponding wires are often used. Proper selection of consumables, along with preheating and PWHT, helps maintain the integrity of the welded joints and ensures compliance with code requirements.
What is the coefficient of thermal expansion for ASTM A387 Grade 12 Class 1?
ASTM A387 Grade 12 Class 1 has a coefficient of thermal expansion similar to other Cr-Mo steels, typically ranging from 11.0–13.0 × 10⁻⁶ per °C between room temperature and 600°C. This property is important for designing pressure vessels and piping systems, as it affects thermal stress and dimensional stability during temperature cycling. Engineers use this data to calculate expansion joints and ensure that the material can withstand thermal gradients without excessive deformation or failure.
What is the thermal conductivity of ASTM A387 Grade 12 Class 1?
The thermal conductivity of ASTM A387 Grade 12 Class 1 decreases with increasing temperature, typically ranging from approximately 45 W/m·K at 100°C to 35 W/m·K at 600°C. This property is important for heat exchanger and boiler applications, as it affects heat transfer efficiency and temperature distribution within the material. Lower thermal conductivity at higher temperatures means more heat is retained, which can influence creep behavior and material selection for specific components.
What is the density of ASTM A387 Grade 12 Class 1?
ASTM A387 Grade 12 Class 1 has a density of approximately 7.85 g/cm³, similar to most carbon and low-alloy steels. This density is used in weight calculations for pressure vessel design and transportation. It also affects the material's inertia and structural response to dynamic loads. While density is not a primary consideration for high-temperature performance, it is an important physical property for engineering and manufacturing processes such as forming, machining, and shipping.
What are the common corrosion resistance characteristics of ASTM A387 Grade 12 Class 1?
ASTM A387 Grade 12 Class 1 offers moderate corrosion resistance due to its chromium content, which helps form a protective oxide layer at high temperatures. However, it is not considered highly corrosion-resistant in aggressive environments such as strong acids or chlorides. In such cases, additional protection such as coatings, linings, or corrosion-resistant alloys may be required. The material is more suited for oxidation resistance in high-temperature service rather than general corrosion resistance in harsh chemical environments.
What are the typical applications of ASTM A387 Grade 12 Class 1 in refineries?
In refineries, ASTM A387 Grade 12 Class 1 is commonly used for pressure vessels, reactors, heat exchangers, and piping headers that operate at elevated temperatures. It is particularly suitable for hydroprocessing units, where high temperatures and pressures are encountered. The material's creep strength and oxidation resistance make it ideal for components exposed to long-term thermal stress. Its weldability also allows for the fabrication of large, complex structures required in modern refinery processes.
What are the typical applications of ASTM A387 Grade 12 Class 1 in power plants?
In power generation facilities, ASTM A387 Grade 12 Class 1 is used for boiler components such as headers, steam drums, and pressure parts that operate at high temperatures and pressures. It is also found in heat recovery steam generators (HRSGs) and auxiliary equipment. The material's ability to withstand thermal cycling and maintain strength at elevated temperatures makes it suitable for these critical applications. Its reliability and compliance with ASME standards ensure the safety and efficiency of power plant operations.
How is ASTM A387 Grade 12 Class 1 specified in engineering drawings?
ASTM A387 Grade 12 Class 1 is typically specified on engineering drawings by including the standard designation, grade, class, thickness, and any additional requirements such as heat treatment, testing, or surface condition. For example, a typical specification might read: "ASTM A387 Grade 12 Class 1, 25 mm thick, normalized and tempered, UT per ASTM A609, Charpy V-notch impact test at 0°C." This ensures that suppliers and fabricators understand the exact material requirements and quality standards for the project.
What quality control measures are applied during the production of ASTM A387 Grade 12 Class 1?
During production, ASTM A387 Grade 12 Class 1 plates undergo strict quality control, including chemical analysis to verify alloy content, mechanical testing to ensure strength and toughness, and heat treatment monitoring to confirm proper normalization and tempering. Non-destructive testing such as ultrasonic inspection is performed to detect internal defects. Manufacturers also maintain detailed records of production and testing to meet ASTM and ASME requirements. These measures help ensure consistent quality and reliability for critical applications.
What are the storage and handling recommendations for ASTM A387 Grade 12 Class 1 plates?
ASTM A387 Grade 12 Class 1 plates should be stored in a dry, covered area to prevent moisture and corrosion. They should be placed on wooden skids to avoid contact with the ground and potential contamination. During handling, care should be taken to prevent scratches, gouges, or other surface damage that could compromise the material's integrity. Plates should be lifted using appropriate slings and clamps to avoid deformation. Proper storage and handling help maintain the material's quality before fabrication.