What are the equivalent grades to SA387 Grade 12 Class 2 in EN or JIS standards?
SA387 Grade 12 Class 2 (also designated as A387 Gr 12 Cl 2) is a high-quality chrome-molybdenum alloy steel plate primarily used for weldable pressure vessels and industrial boilers designed for elevated temperature service.
1. EN (European) Standards
The closest equivalent in the European pressure vessel steel plate standard is:
EN 10028-2: Flat products made of steels for pressure purposes
Designation: 13CrMo4-5 (Material Number: 1.7335)
Condition: Typically supplied in the normalized (+N) or normalized and tempered (+NT) condition to match the N+T treatment of SA387 Gr 12 Cl 2.
Note: The chemical composition (nominally 0.4% Cr, 0.5% Mo) is very similar, though not an exact 1:1 match. It is the accepted and widely used equivalent for design and procurement in Europe.
2. JIS (Japanese) Standards
The common Japanese equivalent is:
JIS G 4118: Chromium-molybdenum alloy steel plates for pressure vessels for intermediate and moderate temperature service
Designation: SCMV 28
Condition: The standard specifies a normalizing and tempering heat treatment, aligning directly with the "Class 2" condition. The "28" denotes a minimum tensile strength of 28 kgf/mm² (~275 MPa).
Chemical Composition of SA387 GR.12 CL.2 Plate
| C | Mn | P | S | Si | Cr | Mo |
| 0.04 - 0.17 | 0.35 - 0.73 | 0.035 | 0.035 | 0.13 - 0.45 | 0.74 - 1.21 | 0.4 - 0.65 |
Mechanical Properties of SA 387 GR.12 CL.2 Plate
| Tensile Strength | Yield Strength | Elongationin 200mm (%) | Elongation in 50mm (%) |
| 65-85 ksi, 450-585 MPa | 40 Ksi, 275 MPa | 19 | 22 |
Key Comparison Table
| Standard | Grade Designation | Condition to Match Class 2 | Key Similarity |
|---|---|---|---|
| EN 10028-2 | 13CrMo4-5 (1.7335) | +N (Normalized) or +NT (Normalized & Tempered) | Similar Cr-Mo content; purpose is pressure vessels at moderate temps. |
| JIS G 4118 | SCMV 28 | Normalized & Tempered (as per standard) | Directly specified N&T condition; similar strength level. |
Critical Considerations for "Equivalence"
1.Condition is Mandatory: "Class 2" means normalized and tempered. Any equivalent must be supplied in a condition (e.g., +NT) that provides comparable mechanical properties (strength, toughness).
2.Not a Perfect Chemical Match: While close, the exact chemical composition ranges (e.g., for C, Si, Mn) differ slightly between standards. The mechanical properties and design allowable stresses are the critical matching parameters.
3.Code Approval is Essential: For fabricating a coded vessel (e.g., ASME BPVC, PED), the selected equivalent grade must be accepted by the governing design code and approved by the responsible engineer. The mill must supply the appropriate certification (e.g., PED 2014/68/EU Module H for EN material).
4.Other Regional Approximations:
GB (China): 15CrMoR is sometimes referenced, but its composition (~1.0Cr-0.5Mo) is closer to SA387 Gr 11. The more accurate Chinese equivalent is 14Cr1MoR.
DIN (Old German): 13CrMo4-4 (1.7334) was the predecessor to the EN grade.
In summary, for EN standards, specify 13CrMo4-5 (+NT). For JIS standards, specify SCMV 28. Always validate suitability through technical data and engineering approval.
1.What is SA387 Grade 12 Class 2?
SA387 Grade 12 Class 2 is a chromium-molybdenum alloy steel plate designed for welded pressure vessels, supplied in the normalized and tempered heat-treated condition for improved toughness and strength.
2.What is the difference between SA387 Gr12 Cl 1 and Cl 2?
The key difference is the mandatory heat treatment. Grade 12 Class 2 must be supplied normalized and tempered, while Class 1 can be supplied as-rolled, annealed, or normalized and tempered, affecting its mechanical properties.
3.What is the chemical composition of SA387 Grade 12 Class 2?
Its typical composition includes Chromium (0.80-1.25%), Molybdenum (0.44-0.65%), Carbon (max 0.17%), Manganese (0.40-0.65%), Silicon (0.15-0.40%), and limited Phosphorus and Sulfur.
4.What are the mechanical properties of SA387 Gr12 Cl 2?
Key properties include a minimum tensile strength of 485 MPa (70 ksi) and a minimum yield strength of 275 MPa (40 ksi) for thicknesses up to 65mm, with higher strength than Class 1.
5.What is SA387 Gr12 Cl 2 equivalent to?
It is equivalent to ASTM A387 Gr12 Cl 2, ASME SA387 Gr12 Cl 2, and the common material grade UNS K11757. It is similar to 1.25%Cr-0.5%Mo steel.
6.What is the heat treatment for SA387 Grade 12 Class 2?
Per the specification, SA387 Grade 12 Class 2 plates are supplied in the normalized (heated above the critical temperature and air-cooled) and subsequently tempered (reheated to a specific sub-critical temperature) condition.
7.Why choose Class 2 over Class 1 for SA387 Grade 12?
Class 2 is chosen when the application requires guaranteed higher strength, better microstructural uniformity, and improved notch toughness due to its mandatory normalized and tempered condition.
8.What is the maximum operating temperature for SA387 Gr12 Cl 2?
It is commonly used for service temperatures up to approximately 800-850°F (427-454°C), particularly in hydrogen service and other high-temperature refinery applications.
9.How to weld SA387 Grade 12 Class 2 steel?
Welding requires preheating (typically 250-400°F / 121-204°C) and a mandatory post-weld heat treatment (PWHT). Common filler metals include AWS E8018-B2 for SMAW or equivalent.
10.What is the hardness of SA387 Grade 12 Class 2?
Hardness is not directly specified in the standard but is controlled by the heat treatment and mechanical properties. For service in wet H2S environments, it is often specified to be below 200 HB or 22 HRC to resist sulfide stress cracking.
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.
