ASTM A387 GRADE 5 Class 2
A high quality ASTM A387 GRADE 5 Class 2 or chrome molybdenum alloy steel plate intended specifically for use in weldable carbon steel pressure vessels at elevated temperatures. Added molybdenum gives the material greater temperature tensile strength and the chromium provides improved corrosion resistance.
Equivalents of ASTM A387 GRADE 5 Class 2
| BS | EN | ASME | DIN |
| ... | ... | A387-5-2 | ... |
Specifications ASTM A387 Grade 5 Alloy Steel Plates
Chromium & Molybdenum content (according to the ASME specification)
| Designation | Nominal Chromium Content (%) |
Nominal Molybdenum Content (%) |
| A387 Grade 5 | 5.00% | 0.50% |
Tensile Requirements for ASTM A387 Grade 5 Alloy Steel Plates Class 2 Plates
| Designation: | Requirement: | Grade 5 |
|
A387 Grade 5 |
Tensile strength, ksi [MPA] | 75 to 100 [515 to 690] |
| Yield strength, min, ksi [MPa]/(0.2% offset) | 45 [310] | |
| Elongation in 8 in. [200mm], min % | ... | |
| Elongation in 2 in. [50mm], min, % | 18 | |
| Reduction of area, min % | 45 (measured on round specimen) 40 (measured on flat specimen) |
Chemical Requirements for ASTM A387 Grade 5 Alloy Steel Plates
| Element | Chemical Composition (%) | |
| A 387 Grade 5 | ||
| Carbon: | Heat Analysis: | 0.15 max |
| Product Analysis: | 0.15 max | |
| Manganese: | Heat Analysis: | 0.30 - 0.60 |
| Product Analysis: | 0.25 - 0.66 | |
| Phosphorus: | Heat Analysis: | 0.035 |
| Product Analysis: | 0.035 | |
| Sulphur (max): | Heat Analysis: | 0.030 |
| Product Analysis: | 0.030 | |
| Silicon: | Heat Analysis: | 0.50 max |
| Product Analysis: | 0.55 max | |
| Chromium: | Heat Analysis: | 4.00 - 6.00 |
| Product Analysis: | 3.90 - 6.10 | |
| Molybdenum: | Heat Analysis: | 0.45 - 0.65 |
| Product Analysis: | 0.40 - 0.70 |
1. How does the chemical composition of A387 Grade 5 differ from Grade 11 or Grade 12?
A387 Grade 5 is a higher-chromium alloy steel, typically containing around 5% chromium and 0.5% molybdenum. This places it between the more common Grade 11 (~1.25% Cr) and Grade 22 (~2.25% Cr), giving it distinct advantages in terms of oxidation resistance and elevated-temperature strength compared to lower-alloy grades, while potentially being more cost-effective than higher-chromium steels for specific service ranges.
2. What are the primary high-temperature service advantages of using Grade 5 Class 2?
The primary advantage of A387 Grade 5 Class 2 lies in its superior oxidation resistance and higher strength retention at temperatures typically ranging from 540°C to 600°C (1000°F to 1112°F), exceeding the capability of Grade 11 or 12. This makes it suitable for components in catalytic crackers, reformer furnaces, and other severe petrochemical service environments where scaling and creep are significant concerns.
3. What are the critical welding and fabrication considerations for A387 Gr.5 Cl.2?
Welding A387 Grade 5 Class 2 requires stringent procedures due to its higher alloy content. It demands mandatory preheating (usually 175-250°C / 350-480°F) and strict interpass temperature control to prevent hard, crack-sensitive microstructures. Furthermore, a mandatory Post-Weld Heat Treatment (PWHT) in the range of 675-730°C (1250-1350°F) is essential to temper the weld zone, relieve stresses, and restore corrosion resistance.
4. What is the standard heat treatment condition for A387 Grade 5 Class 2 plates?
A387 Grade 5 Class 2 plates are supplied in the Normalized and Tempered condition. Normalizing involves heating above the transformation range and air cooling to refine the grain structure, followed by tempering at a sub-critical temperature to achieve the optimal combination of strength and ductility specified in the standard (typically a minimum yield strength of 310 MPa / 45 ksi).
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.
