ASME SA387 Grade 11 Class 2 Steel Plate Specification
ASME SA387 Grade 11 Class 2 is a chromium-molybdenum alloy steel plate used for high-temperature pressure vessels, offering enhanced strength and corrosion resistance due to its ~1.25% Chromium and ~0.50% Molybdenum content, making it ideal for oil, gas, and power industries, with Class 2 indicating higher tensile/yield strength than Class 1. It's specified for elevated temperature service and often supplied normalized and tempered or quenched and tempered.
As a pressure vessel grade steel for use in elevated temperature service, ASME SA387 Grade 11 Class 2 is used in a variety of industries and is highly effective, particularly in the oil, gas and petrochemical industry, where liquids and gases are often stored at higher temperatures.
The higher levels of chromium also provide excellent corrosion and oxidation resistance, which is a must in sour gas applications.
A387 Grade 11 Class 2 – the high-quality chrome moly steel – is used in a wide range of industries and is highly effective, especially in the chemical, oil, and gas industry, where gases and liquids are typically stored at high temperature (see pressure vessels).
In addition, the higher levels of chromium provide excellent resistance against oxidation and corrosion.
Key Characteristics:
Material Type: Chromium-Molybdenum (Cr-Mo) Alloy Steel Plate.
Application: Welded boilers, pressure vessels, heat exchangers in high-temperature, high-pressure environments.
Industry Use: Oil & Gas, Petrochemical, Power Generation.
Composition: Contains approximately 1.00-1.50% Chromium and 0.45-0.65% Molybdenum, providing strength and oxidation resistance.
Class 2 vs. Class 1: Class 2 offers higher tensile and yield strength compared to Class 1.
Benefits:
High-Temperature Performance: Excellent mechanical properties (strength) at elevated temperatures.
Corrosion Resistance: Good resistance to oxidation, crucial for sour gas and corrosive environments.
Fabrication: Suitable for welding with appropriate pre/post-weld heat treatments.
Where it's Used:
Refineries and Chemical Plants.
Power Plants.
Facilities handling high-temperature fluids and gases.
Equivalents
| BS | EN | ASTM/ASME | DIN |
| 621 B | ––– | SA387-11-2 | ––– |
Specifications for ASME SA387 Grade 11 Alloy Steel Plates
| Designation | Nominal Chromium Content (%) |
Nominal Molybdenum Content (%) |
| SA387 Grade 11 | 1.25% | 0.50% |
Tensile Requirements for ASME SA387 Grade 11 Alloy Steel Plates Class 2 Plates
| Designation: | Requirement: | Grade 11 |
| SA387 Grade 11 | Tensile strength, ksi [MPa] | 75 to 100 [515 to 690] |
| Yield strength, min, ksi [MPa]/(0.2% offset) | 43 [310] | |
| Elongation in 8 in. [200mm], min % | 18 | |
| Elongation in 2 in. [50mm], min, % | 22 | |
| Reduction of area, min % | ––– |
Chemical Requirements for ASME SA387 Grade 11 Alloy Steel Plates
| Element | Chemical Composition (%) | |
| SA387 Grade 11 | ||
| Carbon: | Heat Analysis: | 0.05 - 0.17 |
| Product Analysis: | 0.04 - 0.17 | |
| Manganese: | Heat Analysis: | 0.40 - 0.65 |
| Product Analysis: | 0.35 - 0.73 | |
| Phosphorus: | Heat Analysis: | 0.035 |
| Product Analysis: | 0.035 | |
| Sulphur (max): | Heat Analysis: | 0.035 |
| Product Analysis: | 0.035 | |
| Silicon: | Heat Analysis: | 0.50 - 0.80 |
| Product Analysis: | 0.44 - 0.86 | |
| Chromium: | Heat Analysis: | 1.00 - 1.50 |
| Product Analysis: | 0.94 - 1.56 | |
| Molybdenum: | Heat Analysis: | 0.45 - 0.65 |
| Product Analysis: | 0.45 - 0.70 |
1What is ASME SA387 Grade 11 Class 2 equivalent to ?
ASME SA387 Grade 11 Class 2 is a Cr-Mo alloy steel for pressure vessels, primarily equivalent to ASTM A387 Grade 11 Class 2 (same material under ASTM) and corresponds to BS 621B in British Standards, with UNS number K11789, offering higher tensile strength than Class 1 for elevated temperature service.
2What are the primary advantages of ASME SA387 Grade 11 Class 2 ?
ASME SA387 Grade 11 Class 2 offers superior high-temperature strength, excellent corrosion/oxidation resistance (due to chromium/molybdenum), and good weldability, making it ideal for high-pressure vessels in demanding environments like oil & gas and petrochemicals, providing a cost-effective, durable solution with enhanced performance over carbon steel due to its Class 2 heat treatment.
3What are Common Testing Requirements for ASME SA387 Grade 11 Class 2 ?
ASME SA387 Grade 11 Class 2 requires chemical analysis, tensile testing (75-100 ksi tensile strength, 43 ksi min yield), and specific heat treatments (normalized/tempered or quenched/tempered), with Charpy impact tests often required at low temperatures (e.g., -52°C) for toughness, plus optional tests like UT, MPI, and HIC for enhanced performance in high-temp, high-pressure vessel applications.
4What is the hardness of ASME SA387 Grade 11 Class 2?
ASME SA387 Grade 11 Class 2 doesn't have a single fixed hardness value but must meet tensile requirements, typically 75-100 ksi (515-690 MPa) tensile strength and 43 ksi (310 MPa) minimum yield strength, with specific elongation percentages, indicating moderate hardness suitable for high-temperature pressure vessels, often tested for hardness via Brinell or Rockwell to ensure quality, but tensile properties define the class.
5What is the composition of ASME SA387 Grade 11 Class 2?
ASME SA387 Grade 11 Class 2 is a chromium-molybdenum alloy steel for high-temp pressure vessels, primarily composed of 1.00-1.50% Chromium (Cr) and 0.45-0.65% Molybdenum (Mo), along with controlled amounts of Carbon (C), Manganese (Mn), Silicon (Si), Phosphorus (P), and Sulfur (S) for enhanced strength and corrosion resistance at elevated temperatures.
6What is ASME SA387 Grade 11 Class 2material?
ASME SA387 Grade 11 Class 2 is a chromium-molybdenum alloy steel plate designed for high-temperature applications, particularly in pressure vessels, boilers, and heat exchangers, offering excellent oxidation/corrosion resistance, especially in oil, gas, and petrochemical environments, with Class 2 providing higher tensile/yield strength than Class 1 due to specific heat treatment.
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