SA 387 Grade 22 Class 1 is a high-quality chromium-molybdenum alloy steel plate specified by ASME (American Society of Mechanical Engineers) and ASTM (American Society for Testing and Materials).
It is specifically designed for use in welded boilers and pressure vessels that operate in high-temperature and high-pressure environments, such as those found in refineries and power plants.
Chemical Composition( %):
|
Grade/ Material |
Element |
Composition( Max-A, Min-I) |
|
SA387 Grade 22 Class 1/ SA387 Gr22 Cl1 |
C |
0.05-0.15 |
|
Mn |
0.30-0.60 |
|
|
Si |
A:0.50 |
|
|
P |
0.035 |
|
|
S |
0.035 |
Mechanical Properties( Mpa)
|
Grade/ Material |
Tensile Test |
Ksi/MPa |
|
SA387 Grade 22 Class 1/ SA387 Gr22 Cl1 |
Tensile Strength |
60-85/415-585 |
|
Yield Strengh |
30/205 |
|
|
Elongation |
18% |
|
|
Impact Test( if any) |
|
processing
1. Primary Forming & Cutting
Method: High-precision oxygen-acetylene or plasma cutting is standard.
Pre-Processing: Plates are typically supplied in Normalized and Tempered (N+T) or Quenched and Tempered (Q+T) conditions.
Edge Prep: Beveling (typically 37.5°) is performed on plate edges to ensure deep weld penetration for pressure-retaining joints.
2. Welding Procedure
Due to the material's sensitivity to hydrogen, welding is the most critical processing phase.
Preheating: Essential to avoid cold cracking. Surfaces are preheated to 150°C–250°C before welding begins.
Matching Consumables: Matching 2.25% Cr - 1% Mo electrodes (e.g., E9018-B3) or 1.25% Cr - 0.5% Mo fillers are used depending on the specific service environment.
Interpass Control: Temperatures must be strictly maintained between weld passes to prevent the formation of brittle phases.
Post-Weld Soaking: Often, a dehydrogenation heat treatment (DHT) is applied immediately after welding to allow hydrogen to diffuse.
3. Thermal Processing & Heat Treatment
Standard 2026 industry requirements for SA 387 Grade 22 Class 1 include:
Minimum Tempering: Must be tempered at a minimum of 675°C (1250°F) to achieve the Class 1 tensile strength requirement of 60–85 ksi.
PWHT (Post-Weld Heat Treatment): This is mandatory for Grade 22 to relieve residual stresses and improve ductility. Typical soaking occurs at approximately 690°C ± 10°C.
Simulated PWHT (SPWHT): For critical applications, third-party simulated tests are performed on material coupons to ensure the finished product will maintain its properties after the actual fabrication heat treatment.
4. Quality Inspection (NDE)
To confirm the success of the processing, several tests are required:
Radiography (RT): 100% radiography testing is standard for high-pressure vessels to verify weld integrity.
Ultrasonic Testing (UT): Used for internal flaw detection, particularly for plates exceeding certain thicknesses (e.g., 4 to 10 inches).
Hardness Testing: Ensures the Heat Affected Zone (HAZ) has not exceeded specified limits (typically <225 HBW for hydrogen service).
API 934 Testing: For severe environments, supplemental testing (like step cooling) is performed to measure susceptibility to temper embrittlement.
applications
1. Oil, Gas, and Petrochemical Refining
This alloy is the industry standard for equipment exposed to sour gas (H₂S) and high-pressure hydrogen service.
Reactors and Separators: Used for hydrocrackers and catalytic reformers where high creep strength is required.
Heat Exchangers and Piping: Ideal for transport systems handling heated fluids that would cause rapid oxidation in standard carbon steels.
Storage Tanks and Pressure Vessels: Designed for the safe containment of pressurized gases and liquids at elevated temperatures.
2. Power Generation
In both thermal and nuclear power plants, SA 387 Grade 22 Class 1 is used for components that must withstand continuous thermal cycling.
Industrial Boilers and Drums: Crucial for constructing weldable pressure vessels and boiler drums that operate under high-pressure steam conditions.
Superheater and Reheater Tubes: Selected for its ability to maintain structural integrity at temperatures up to 600°C (1112°F).
Nuclear Components: Due to its high-temperature performance and durability, it is increasingly used in modern nuclear reactor support structures.
3. Chemical Processing and Heavy Industry
Chemical Reactors: Used in vessels where chemical processing media requires both mechanical strength and resistance to stress corrosion cracking.
High-Temperature Ducting and Valves: Applied in industrial furnace components and ductwork exposed to cyclic thermal loads.
Subsea and Offshore Equipment: Used in gas processing and seawater equipment where corrosion resistance is paramount.
Full specification and details are available on request. The above information is provided for guidance purposes only. For specific design requirements please contact our technical sales staff.
What is the heat treatment process for SA387 Grade 22 Class 1?
It usually undergoes normalizing (899-954°C) followed by tempering (593-704°C). This process enhances strength, toughness, and microstructure uniformity for pressure vessel service.
What is the density of SA387 Grade 22 Class 1?
The density of SA387 Grade 22 Class 1 is approximately 7.85 g/cm³ (0.284 lb/in³), consistent with most low-alloy steels, facilitating weight calculation in equipment design.
What is the hardness range of SA387 Grade 22 Class 1 after heat treatment?
After standard heat treatment, its Brinell hardness (HB) ranges from 137 to 187. This hardness balance ensures machinability and resistance to deformation under operating loads.
Can SA387 Grade 22 Class 1 be used in low-temperature environments?
It is not ideal for low temperatures (below -20°C) as its impact toughness decreases. For cryogenic service, choose grades with better low-temperature performance like SA387 Grade 11.
What is the thickness range of SA387 Grade 22 Class 1 plates?
Common thickness ranges from 6 mm to 200 mm. Thicker plates may require adjusted heat treatment to ensure uniform mechanical properties throughout the cross-section.
What is the melting point of SA387 Grade 22 Class 1?
Its melting point ranges from 1455°C to 1500°C (2651°F to 2732°F), similar to other Cr-Mo low-alloy steels, providing stability in high-temperature processing and service.
Is SA387 Grade 22 Class 1 magnetic?
Yes, it is ferromagnetic due to its iron-based composition. This property allows magnetic particle inspection (MPI) for detecting surface and near-surface defects.
What inspection methods are used for SA387 Grade 22 Class 1 plates?
Common methods include ultrasonic testing (UT) for internal defects, MPI for surface flaws, visual inspection (VI), and chemical composition analysis to ensure compliance with standards.
What is the coefficient of thermal expansion of SA387 Grade 22 Class 1?
At 20-500°C, its average thermal expansion coefficient is about 12.1 × 10⁻⁶/°C. This data is critical for thermal stress calculation in high-temperature equipment design.