Compare With SA-387 Steel Plates Grade 11 & 22
A387 Grade 22 Class 1 is a normalized chromium-molybdenum alloy steel plate (2.25% Cr, 1% Mo) designed for high-temperature, high-pressure welded pressure vessels. Supplied in the normalized or stress-relieved condition , it is intended for fabrications where the completed vessel will undergo a full Post-Weld Heat Treatment (PWHT) to develop its final tempered microstructure, stress relief, and optimal mechanical properties for severe service, such as in hydrocracker reactors and high-temperature hydrogen environments.
Overview SA 387 Gr 11 / SA 387 Gr 22
More common application of this grade is in Refineries, Power Plants, and certain areas of Chemical Plants in environments with elevated temperatures and limited corrosion concerns. In the lower end of the temperature range SA 387 Gr 11 (1150 °F min tempering temperature) , and SA 387 Gr 22 (1250 °F min tempering temperature) are used. These grades can be specified in either class 1 or 2 and can also be provided in the Normalized & Tempered or Quenched and Tempered. For more severe environments we can perform API 934 Testing to supplement this grade.
Provided in Normalized and Tempered or Quenched and Tempered
Thickness' from 3/16" – 10"
Supplemental testing available to simulate application and environment conditions
Elevated temper to accommodate API 934
Chemical Requirements
*Elements represented in percentage
| Element Composition % | ||
|---|---|---|
| SA 387 Grade 11 |
SA 387 Grade 22 |
|
| Carbon, max: | ||
| Heat analysis | 0.05-0.17 | 0.05-0.15A |
| Product analysis | 0.04-0.17 | 0.04-0.15A |
| Manganese, max: | ||
| Heat analysis | 0.40-0.65 | 0.30-0.60 |
| Product analysis | 0.35-0.73 | 0.25-0.66 |
| Phosphorus, max: | ||
| Heat analysis | 0.025 | 0.025 |
| Product analysis | 0.025 | 0.025 |
| Sulfur, max: | ||
| Heat analysis | 0.025 | 0.025 |
| Product analysis | 0.025 | 0.025 |
| Silicon: | ||
| Heat analysis | 0.50-0.80 | 0.50 max |
| Product analysis | 0.44-0.86 | 0.50 max |
| Chromium: | ||
| Heat analysis | 1.00-1.50 | 2.00-2.50 |
| Product analysis | 0.94-1.56 | 1.88-2.62 |
| Molybdenum: | ||
| Heat analysis | 0.45-0.65 | 0.90-1.10 |
| Product analysis | 0.40-0.70 | 0.85-1.15 |
Tensile Requirements For Class 1 Plates
| SA 387 Grade 11 |
SA 387 Grade 22 |
|
|---|---|---|
| Tensile strength, ksi [MPa] | 60 to 85 [415 to 585] |
60 to 85 [415 to 585] |
| Yield strength min. ksi [MPa] | 35 | 30 |
| Elongation in 8 in. [200 mm], min. % | 19 | |
| Elongation in 2 in. [50 mm], min. % | 22 | 18 |
| Reduction of area, min % | 45 40 |
Tensile Requirements For Class 2 Plates
| SA 387 Grade 11 |
SA 387 Grade 22 |
|
|---|---|---|
| Tensile strength, ksi [MPa] | 75 to 100 [515 to 690] | 75 to 100 [515 to 690] |
| Yield strength min. ksi [MPal]/(0.2% offset) | 45 [310] | 45 [310] |
| Elongation in 8 in. [200 mm], min. %B | 18 | … |
| Elongation in 2 in. [50 mm], min. %B | 22 | 18 |
| Reduction of area, min % | … | 45 40 |
1. Why would an engineer specify A387 Grade 22 Class 1 instead of Class 2 for a pressure vessel?
This question focuses on the fundamental design and fabrication logic behind choosing the softer, normalized condition of Class 1, typically for components requiring extensive welding and subsequent full heat treatment.
2. What is the critical post-fabrication step required for A387 Grade 22 Class 1 to achieve its intended properties?
This question highlights the essential role of the mandatory Post-Weld Heat Treatment (PWHT) process that transforms the normalized Class 1 material into a vessel with the proper strength and toughness.
3. How does the PWHT temperature range for A387 Grade 22 Class 1 differ from that of Grade 11?
This question explores the practical welding procedure differences, as the higher alloy content of Grade 22 requires a higher PWHT temperature range to properly temper the microstructure.
4. What is the main advantage of using A387 Grade 22 Class 1 in severe hydrogen service?
This question targets the material's core application driver, linking its 2.25Cr-1Mo chemistry to its superior resistance to high-temperature hydrogen attack compared to lower alloys.
5. What are the potential risks if A387 Grade 22 Class 1 is not given a proper PWHT after welding?
This question addresses a critical safety and quality concern, focusing on the consequences of leaving a hard, brittle microstructure in the weld heat-affected zone.
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.
