SA387 Grade 11 Class 1-pressure vessel grade steel
As a pressure vessel grade steel for use in elevated temperature service, 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. Please refer to our technical specifications below for ASME SA387 Grade 11 Class 1.
Equivalents OF SA387 Grade 11 Class 1
| BS | EN | ASTM/ASME | DIN |
| 621 B | ––– | SA387-11-1 | ––– |
Specifications for ASME SA387 Grade 11 Alloy Steel Plates
Chromium & Molybdenum content (according to the ASME specification)
| 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 1 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 |
1. What is the key mechanical property difference between SA387 Grade 11 Class 1 and Class 2?
SA387 Grade 11 Class 1 is supplied in the annealed condition, offering lower strength but higher ductility and better formability, while Class 2 is normalized and tempered for higher yield and tensile strength, making Class 1 preferable for severe cold forming applications where stress relief will follow fabrication.
2. What are the primary high-temperature applications for SA387 Grade 11 Class 1 plates?
SA387 Grade 11 Class 1 is commonly used in petrochemical and power generation industries for components like hydrogen reformers, catalytic reactors, and high-temperature heat exchangers that operate up to about 595°C (1100°F), where its 1.25% chromium and 0.5% molybdenum content provide good oxidation and creep resistance.
3. Why is post-weld heat treatment (PWHT) critical for SA387 Grade 11 Class 1 weldments?
PWHT is mandatory for SA387 Grade 11 Class 1 after welding to relieve residual stresses, prevent hydrogen-induced cracking, and restore the microstructure in the heat-affected zone, typically performed at 620–690°C (1150–1275°F) to ensure long-term integrity in high-temperature service.
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.
