SA537 Class 2 (also designated as ASME SA537 Cl 2 or ASTM A537 Cl 2) is a heat-treated, carbon-manganese-silicon steel plate specifically engineered for fusion-welded pressure vessels and structural applications. It is characterized by higher yield and tensile strength compared to Class 1, achieved through a Quenched and Tempered (Q&T) heat treatment process.
Mechanical Properties
|
Grade |
Yield strength |
Tensile strength |
Elongation in 2" |
|---|---|---|---|
|
SA537 Class 2 |
60 |
80 - 100 |
22 |
Chemical Composition
|
C |
Mn 1) |
P 2) |
S 2) |
Si |
Cu |
Ni 1) |
Cr |
Mo |
|---|---|---|---|---|---|---|---|---|
|
0.24 |
1.60 |
0.020 |
0.010 |
0.50 |
0.35 |
0.25 |
0.25 |
0.080 |
Carbon Equivalent
|
Thickness (in) |
0.375 - 2.00 |
|---|---|
|
Typical CET (wt %) |
0.33 |
|
Typical CEV (wt %) |
0.45 |
Formability properties
|
Thickness(in. [mm]) |
Bend Axis Perpendicular to Rolling Direction Inside Radius, R (min.) |
Bend Axis Perpendicular to Rolling Direction Die Width, W (min.) |
Bend Axis Parallel to Rolling Direction Inside Radius, R (min.) |
Bend Axis Parallel to Rolling Direction Die Width, W (min.) |
|---|---|---|---|---|
|
0.375 – 1.00 [9.5 – 25.4] |
1.5t |
8t |
2.25t |
10t |
|
1.00 – 2.00 [25.4 – 50.1] |
2.0t |
8t |
3.0t |
10t |
Main Applications
Oil, Gas and Petrochemical Industry：Widely used in core equipment such as thick-walled reactors for hydrocracking/hydrotreating, fractionating towers and distillation towers. Also applicable to high-pressure pipelines and header pipes, resisting erosion from high-pressure hydrocarbon media and temperature fluctuation impacts during oil-gas exploration, transportation and refining.
Power Generation Systems：Suitable for key components like high-pressure drums and feedwater heaters in thermal power stations. It can also be used for secondary containment and structural shielding of small modular nuclear reactors, maintaining stable mechanical properties under high-temperature steam circulation and radiation environments.
Cryogenic Storage and Transportation：Due to excellent low-temperature toughness, it is used to manufacture LNG storage tanks, low-temperature transport vessels and API 650/620 standard storage tanks, preventing brittle fracture risks in low-temperature media storage and transportation.
Boilers and Pressure Vessels：Primary material for fusion-welded pressure vessels and boilers, used to store and transport high-pressure gases and liquids, ensuring equipment sealing and structural stability under moderate to high temperatures and pressures.
Offshore Engineering：Applied in offshore platforms and arctic pipelines, adapting to harsh marine environments with high pressure and low temperatures.
Application Conditions
Mechanical Property Requirements：Yield strength ≥415MPa, tensile strength 550-690MPa, elongation ≥22%. Charpy V-notch impact test is mandatory (e.g., ≥20J at -45°C), complying with ASME BPVC Section VIII.
Material and Standard Compliance：Must meet ASME SA 537/SA 537 M standards. Chemical composition is strictly controlled (C≤0.24%, P/S≤0.035% each), with ultrasonic examination per ASME SA-578 Class 1 to ensure no laminations.
Operating Environment Limits：Suitable for temperatures from -68°C (plate thickness ≤65mm) to high-temperature environments with cyclic loading and thermal stress, not applicable to ultra-high temperature (>500°C) or strong corrosion environments beyond its resistance range.
Fabrication Requirements：Welding requires preheating (95-150°C) and post-weld heat treatment (PWHT) with low-hydrogen electrodes (e.g., AWS E7018) to prevent hydrogen cracking. Machinability is suitable for hardness 137-149 HB.
Dimension and Delivery Conditions：Common thickness 6-150mm, width up to 4000mm, length up to 18000mm. Delivered in quenched and tempered (Q+T) state to ensure optimal toughness and ductility.
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 SA 537 Class 2?
SA 537 Class 2 is a carbon-manganese steel plate heat-treated (quenched and tempered) for pressure vessel applications. It offers excellent strength, toughness, and weldability, widely used in oil, gas, and petrochemical industries under moderate to severe service conditions.
What are the main chemical compositions of SA 537 Class 2?
The key chemical elements include carbon (0.18-0.25%), manganese (1.00-1.60%), phosphorus (max 0.035%), sulfur (max 0.035%), silicon (0.15-0.40%), nickel (max 0.25%), chromium (max 0.25%), and molybdenum (max 0.08%).
What is the minimum yield strength of SA 537 Class 2?
The minimum yield strength of SA 537 Class 2 is 345 MPa (50,000 psi). This high yield strength ensures the material can withstand high pressure and load without permanent deformation in pressure vessel operations.
What is the tensile strength range of SA 537 Class 2?
SA 537 Class 2 has a tensile strength range of 485-655 MPa (70,000-95,000 psi). This range balances strength and ductility, making it suitable for harsh service environments requiring reliable structural performance.
What heat treatment process is required for SA 537 Class 2?
SA 537 Class 2 must undergo quenching and tempering (Q&T) heat treatment. Quenching involves rapid cooling from above the austenitizing temperature, followed by tempering at a controlled temperature to reduce brittleness and optimize toughness.
What is the maximum service temperature for SA 537 Class 2?
The maximum recommended service temperature for SA 537 Class 2 is approximately 482°C (900°F). Exceeding this temperature may degrade its mechanical properties, affecting structural integrity in pressure vessel applications.
Is SA 537 Class 2 weldable?
Yes, SA 537 Class 2 is highly weldable. Proper preheating (typically 93-204°C) and post-weld heat treatment (PWHT) are recommended to prevent cold cracking and relieve residual stresses, ensuring sound weld joints.
What standards govern SA 537 Class 2?
SA 537 Class 2 is governed by the ASTM A537 standard (American Society for Testing and Materials). This standard specifies the requirements for heat-treated carbon-manganese steel plates for pressure vessels and boilers.
What is the difference between SA 537 Class 1 and Class 2?
The main difference lies in strength: SA 537 Class 2 has higher yield and tensile strength than Class 1. Class 2 undergoes stricter heat treatment, making it suitable for more demanding pressure and load conditions.
What applications is SA 537 Class 2 commonly used for?
SA 537 Class 2 is widely used in pressure vessels, boilers, storage tanks, and reactor vessels in oil refining, gas processing, petrochemical, and power generation industries, especially for moderate to high-pressure services.