What temperature is ASTM A387 Grade 11 Class 2 ？

What temperature is ASTM A387 Grade 11 Class 2 ?

ASTM A387 Grade 11 Class 2 is a chromium-molybdenum alloy steel designed for elevated temperatures, often used in high-temp pressure vessels, with typical service ranges from around 350°C to 480°C (660°F to 900°F), though it can be used at higher temperatures (up to 649°C or 1200°F) in specific ASME code applications, with its properties (like higher strength than Class 1) achieved through normalized and tempered heat treatment at about 620°C (1150°F).

ASTM A387 Grade 11 Class 2 is a low-alloy steel specification designed for pressure vessel plates used in high-temperature environments. Characterized by its nominal composition of 1.25% Chromium and 0.5% Molybdenum, this alloy is specifically formulated to provide a robust balance of mechanical strength and chemical stability. The molybdenum content significantly enhances the steel's "creep" resistance-the ability to resist slow deformation under constant stress at high heat-while the chromium provides a protective layer against oxidation and corrosion. This makes it an essential material for the fabrication of industrial boilers and heat exchangers that operate in the demanding conditions of oil refineries and chemical processing plants.

Distinguished from Class 1 by its superior mechanical profile, the Class 2 designation requires a more rigorous heat treatment process, usually involving normalizing and tempering. This metallurgical process increases the material's load-bearing capacity, resulting in a tensile strength of 515 to 690 MPa (75 to 100 ksi) and a minimum yield strength of 310 MPa (45 ksi). While it offers higher strength than its Class 1 counterpart, it retains the excellent weldability and durability required for complex vessel construction. These attributes ensure that the steel can withstand the intense internal pressures and thermal cycling typical of modern petrochemical and power generation infrastructure.

Key Characteristics

Composition: ~1.25% Chromium, ~0.5% Molybdenum.

Heat Treatment: Normalized and Tempered (minimum tempering temp ~620°C).

Properties (Class 2): Higher strength than Class 1 due to treatment.

Tensile Strength: 75-100 ksi (515-690 MPa).

Yield Strength: Min 43 ksi (310 MPa).

Impact Tested: Often to -52°C.

Class 1 vs. Class 2

Class 1: Lower strength requirements.

Class 2: Highe

Application: Welded boilers, pressure vessels, heat exchangers in elevated temperature service.

Industries: Petrochemical, Oil & Gas, Power Generation.

Is ASTM A387 Grade 11 Class 2 carbon steel? ?

No, ASTM A387 Grade 11 Class 2 is not plain carbon steel; it's a chromium-molybdenum (Cr-Mo) alloy steel, specifically designed for high-temperature pressure vessels, with added chromium (around 1-1.5%) and molybdenum (around 0.5%) for enhanced strength, corrosion resistance, and creep resistance, distinguishing it from basic carbon steels. The "Class 2" designation indicates higher strength requirements achieved through specific heat treatment (normalized and tempered) compared to Class 1,

What welding rod for ASTM A387 Grade 11 Class 2 ?

For ASTM A387 Grade 11 Class 2 (a 1.25Cr-0.5Mo alloy), use low-carbon chromium-molybdenum electrodes like E7018-B2L (SMAW/Stick), E8018-B2 or E8018-B3 (for P11 to P22), ER80S-B2 or ER90S-B3 (TIG/MIG), or appropriate flux-cored options like E9XT1-B3C, ensuring matching chemistry, proper preheat (around 150-200°C), and post-weld heat treatment (PWHT) for optimal performance in high-temperature pressure vessels.

Is ASTM A387 Grade 11 Class 2 high speed steel?

No, ASTM A387 Grade 11 Class 2 is not high-speed steel (HSS); it's a chromium-molybdenum (Cr-Mo) alloy pressure vessel steel designed for high-temperature strength, creep resistance, and corrosion resistance, commonly used in boilers and petrochemical equipment, whereas high-speed steels are tool steels with high tungsten/molybdenum content for cutting tools. Grade 11 Class 2 offers enhanced mechanical properties like higher yield strength than Class 1 due to additional heat treatment (normalized and tempered) for demanding elevated temperature service.

Equivalents

Chemical Requirements:

ASTM A387 GR 11 CLASS 2 Plate Specification

Tensile Requirements for ASTM A387 Grade 11 Alloy Steel Plates Class 1 Plates

1What are the typical application fields of ASTM A387 Grade 11 Class 2 ?

ASTM A387 Grade 11 Class 2 steel is primarily used for elevated temperature service in pressure vessels, boilers, and heat exchangers, especially within the oil, gas, petrochemical, and power generation industries due to its excellent strength, weldability, and resistance to corrosion and oxidation at high temperatures. Key applications include hydrogenation reactors, hydrocracking units, steam headers, and storage tanks in demanding environments.

2What precautions should be taken when welding ASTM A387 Grade 11 Class 2?

When welding ASTM A387 Grade 11 Class 2 (a 1.25Cr-0.5Mo alloy), key precautions include thorough cleaning, mandatory preheating (around 149°C/300°F), using low-hydrogen electrodes (like E8018-B2), controlling interpass temperature, and applying Post-Weld Heat Treatment (PWHT) (around 690°C/1275°F) to prevent cracking due to its tendency to form brittle martensite, requiring adherence to ASME/AWS codes for specific parameters.

3What is the difference between ASTM A387 Grade 11 Class 2 and ASTM A387 Grade 11 Class 1 ?

ASTM A387 Grade 11 Class 2 is a stronger, tougher version of Grade 11 Class 1, primarily differing in mechanical properties (higher tensile/yield strength) due to potentially different heat treatment, making Class 2 suitable for more demanding high-temperature/pressure applications than Class 1, while both share the same 1.25% Cr-0.5% Mo composition for pressure vessels.

4What is the hardness of ASTM A387 Grade 11 Class 2 ?

ASTM A387 Grade 11 Class 2 steel's hardness isn't a single fixed number but varies with tempering, though it typically has a Brinell hardness of around 170-207 HBW (or roughly 190 HBW as one example), reflecting its higher strength Class 2 designation, with specified minimum tensile strength often around 515-690 MPa (75-100 ksi) after heat treatment for pressure vessels.

5What is ASTM A387 Grade 11 Class 2 equivalent to ?

ASTM A387 Grade 11 Class 2 is equivalent to ASME SA387 Grade 11 Class 2 (the ASME boiler and pressure vessel code version) and has international counterparts like EN 10028 13CrMoSi5-5 and British Standard BS 621B, all offering similar 1.25% Chromium, 0.50% Molybdenum alloy steel with specific higher tensile strength properties for high-temperature pressure applications.

6What is ASTM A387 Grade 11 Class 2 material?

ASTM A387 Grade 11 Class 2 is a chromium-molybdenum (Cr-Mo) alloy steel plate for high-temperature pressure vessels, offering higher strength than Class 1 due to stricter heat treatment, with around 1.25% chromium and 0.5% molybdenum for excellent high-temp strength, creep, and oxidation resistance, used in oil, gas, and chemical industries. It's known for applications like reactors and heat exchangers requiring elevated temperatures.

7What is the P number of ASTM A387 Grade 11 Class 2 ?

The P-Number for ASTM A387 Grade 11 Class 2 alloy steel, used in pressure vessels, is P-Number 4, which designates low alloy steels (Cr-Mo) that fall within specific compositional ranges for welding group classification. This material is characterized by its 1.25% Chromium and 0.5% Molybdenum content, differing from other grades by its mechanical properties (Class 2 having higher strength than Class 1) but sharing the same base chemistry,

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