What is SA387 grade 11 equivalent to?
The most direct and important equivalent for SA387 Grade 11 (the ASME designation) is its UNS number and its nearest international counterparts. The equivalency always assumes the normalized and tempered (N&T) condition unless "Class 1" is specified.
| Standard / Region | Equivalent Designation | Key Notes |
|---|---|---|
| ASME (USA) | SA387 Grade 11 | The mandatory code specification for pressure vessel construction in North America. |
| UNS (USA) | K11789 | The standardized material number. |
| EN / DIN (Europe) | 13CrMo4-5 (1.7335) | This is the closest and most commonly referenced European equivalent. The composition (1.0-1.5% Cr, 0.5-0.7% Mo) and application are nearly identical. |
| JIS (Japan) | SCMV 410 | Japanese pressure vessel steel standard. |
| GB (China) | 15CrMoR | The primary Chinese equivalent pressure vessel plate steel. The "R" denotes "容器" (container/vessel). |
| Common Alloy Name | 1¼Cr-½Mo or 1.25Cr-0.5Mo | The universal industry shorthand based on its nominal chromium and molybdenum content. |
Critical Clarifications for Equivalency:
SA-387 vs. A-387: "SA387" is the ASME BPVC Section II designation, implying the material meets additional manufacturing and quality requirements for code construction. "A387" is the base ASTM material specification. In practice, they are used interchangeably, but for a code vessel, SA387 is the required purchase.
Condition is Key (Class 1 vs. Class 2):
Grade 11 Class 2 is supplied in the Normalized and Tempered condition (higher strength). Most international equivalents (like 13CrMo4-5) are aligned with this condition.
Grade 11 Class 1 is supplied in the Annealed condition (softer, more formable). This is less common and requires specific ordering.
Not a Direct Equivalent to AISI 4130: While their chemistries are similar, they are not interchangeable. A387 Gr.11 is a plate product for pressure vessels with specific notch toughness and quality requirements. AISI 4130 is a general-purpose structural/bar alloy with different property ranges and testing.
In summary
for global engineering and procurement, the most important equivalents are:
SA387 Grade 11 (ASME Code)
13CrMo4-5 (EN/DIN - Europe)
15CrMoR (GB - China)
Always specify the required Class (1 or 2) and confirm that the equivalent material meets the necessary heat treatment condition and testing for your application.
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.
