ASTM A387 | Grade 5 Class 2 | Alloy Steel Plate

ASTM A387 Grade 5 Class 2 Alloy Steel Plate

The core composition of this alloy steel incorporates molybdenum, imparting remarkable tensile strength and impressive resistance to corrosion. These plates adhere strictly to the guidelines of ASTM A387, an industry-standard specification governing the production of welded molybdenum steel plates. Their prominence is especially notable in applications requiring performance in elevated temperature conditions.

ASTM A387 Grade 5 Class 2 is a high-performance chromium-molybdenum alloy steel plate specifically engineered for use in weldable pressure vessels and industrial boilers operating at elevated temperatures. This grade features a high chromium content of 4.00% to 6.00% and molybdenum content of 0.45% to 0.65%, providing the material with exceptional resistance to oxidation, hydrogen attack, and corrosion. It is an essential material in the oil, gas, and petrochemical sectors, particularly for "sour service" environments where the steel must withstand chemical degradation under intense heat.

As a Class 2 material, this grade is heat-treated (typically through normalizing and tempering) to achieve higher mechanical strength compared to Class 1. It offers a robust tensile strength range of 515 to 690 MPa (75 to 100 ksi) and a minimum yield strength of 310 MPa (45 ksi). This combination of high tensile strength and thermal stability makes it a versatile solution for fabricating large-scale heat exchangers and reactors that require long-term durability and structural integrity in severe high-temperature applications.

Key Characteristics:

Composition: Contains approximately 4-6% Chromium (Cr) and 0.45-0.65% Molybdenum (Mo).

Properties: Offers good tensile strength, yield strength, hardness, and toughness at high temperatures, along with resistance to oxidation and corrosion.

Applications: Widely used in the chemical, petrochemical, oil & gas, and fertilizer industries for equipment like boilers, heat exchangers, and pressure vessels.

Heat Treatment: Usually supplied in the normalized and tempered condition.

Will the material be delivered in a Normalized and Tempered (N+T) condition as per ASTM A387 Grade 5 Class2 requirements ?

Yes, ASTM A387 Grade 5 Class 2 steel is typically delivered in a Normalized and Tempered (N+T) condition, which is the standard heat treatment for this alloy to achieve its specified high-temperature mechanical properties, like superior tensile strength and creep resistance, making it ideal for pressure vessels.

Do you perform Simulated Post-Weld Heat Treatment (S-PWHT) on theASTM A387 Grade 5 Class2? If so, what are the soaking time and temperature ?

Yes, Simulated PWHT (S-PWHT) is performed on ASTM A387 Gr 5 Cl 2 (Chrome-Moly Steel) to relieve residual stress, but specific times and temperatures (e.g., 600-650°C for 1-2 hours/inch, following codes like ASME Sec. VIII/B31.3) depend on the exact material (Grade 5, Type 1 or 2) and application, requiring reference to the governing code (like ASME B31.3 or Section VIII) for precise parameters to avoid embrittlement or strength loss, with typical soaking around 600-650°C (1110-1200°F) for stress relief.

What is the guaranteed minimum Charpy V-notch impact energy at 0°C after S-PWHT on the ASTM A387 Grade 5 Class 2?

For ASTM A387 Grade 5 Class 2 steel, the minimum Charpy V-notch energy after post-weld heat treatment (PWHT) depends on thickness and test direction (longitudinal/transverse), but typically requires 27 Joules (J) for transverse tests and 41 Joules (J) for longitudinal tests, often tested at temperatures around 0°C or lower depending on service conditions, with specific standards (like IACS UR W11) setting minimums like 27J average for plates/sections and 41J for welds, especially with PWHT.

Equivalents

Specifications ASTM A387 Grade 5 Alloy Steel Plates

Tensile Requirements for ASTM A387 Grade 5 Alloy Steel Plates Class 2 Plates

Chemical Requirements for ASTM A387 Grade 5 Alloy Steel Plates

1What is ASTM A387 Grade 5 Class2 ?

ASTM A387 Grade 5 Class 2 is a chromium-molybdenum alloy steel plate designed for high-temperature service in welded boilers and pressure vessels, featuring excellent high-temperature strength, toughness, and improved corrosion resistance due to its chromium content. The "Grade 5" signifies 4-6% chromium, while "Class 2" indicates a higher tensile strength level, and it's typically supplied in a normalized and tempered condition for enhanced mechanical properties at elevated temperatures.

2What is ASTM A387 Grade 5 Class2 equivalent to ?

ASTM A387 Grade 5 Class 2 is a chromium-molybdenum alloy steel for pressure vessels, primarily equivalent to ASME SA387 Grade 5 Class 2, with European equivalents including EN 10028-2 10CrMo5-5, and Russian standards like GOST 15KhM, offering specific mechanical properties (higher strength) and elevated temperature resistance due to its ~5% Chromium and ~0.5% Molybdenum content.

3What are the primary advantages of ASTM A387 Grade 5 Class2 ?

The primary advantages of ASTM A387 Grade 5 Class 2 steel are its excellent strength at high temperatures, superior corrosion resistance (especially in harsh chemical/oil & gas environments), good weldability, and enhanced toughness/durability, thanks to its chromium and molybdenum content, making it ideal for pressure vessels, boilers, and equipment in high-heat, corrosive industries.

4What are the typical application fields of ASTM A387 Grade 5 Class2 ?

ASTM A387 Grade 5 Class 2 plates, a chromium-molybdenum alloy steel, are primarily used in high-temperature, high-pressure applications like pressure vessels, boilers, heat exchangers, and piping within the oil & gas, petrochemical, chemical, and power generation industries, valued for their strength, corrosion resistance, and weldability.

5What precautions should be taken when welding ASTM A387 Grade 5 Class2 ?

When welding ASTM A387 Grade 5 Class 2 (a < chrome-moly alloy steel for pressure vessels), focus on preheating, interpass temperature control, post-weld heat treatment (PWHT) to prevent cracking, using appropriate low-hydrogen consumables, ensuring good ventilation for fumes, and wearing proper PPE (helmet, gloves, respirator, non-flammable clothing) for electrical, heat, radiation, and fire hazards, as it's a high-strength alloy requiring careful procedure.

6What are Common Testing Requirements ASTM A387 Grade 5 Class2 ?

ASTM A387 Grade 5 Class 2 requires specific chemical composition (around 5% Chromium, 0.5% Molybdenum), heat treatment (normalized and tempered), and mechanical properties (tensile strength 75-100 ksi, yield 45 ksi min, 18% elongation in 2"). Common tests include chemical analysis (for Cr, Mo, C, etc.), tensile testing, and elongation, with impact testing often done for low-temp applications, all documented via Mill Test Certificates (MTC).

7What is the chemical composition of ASTM A387 Grade 5 Class2 ?

ASTM A387 Grade 5 Class 2 is a chromium-molybdenum alloy steel for pressure vessels, characterized by its high chromium (4.00-6.00%) and molybdenum (0.45-0.65%) content, providing excellent high-temperature strength and corrosion resistance, with specific limits on carbon (0.15% max), manganese (0.30-0.60%), phosphorus (0.025% max), and sulfur (0.025% max).

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