Production Size: Thickness: 4mm- 400mm; Width: 1000mm- 4000mm; Length: 4000mm- 12000mm.
Production Way: Hot Rolled, Annealing, Normalizing, Tempering.
Technical Details:
Heat Treatment: Normalized, Quenched, Tempered, HIC, Impact Test,..( Optional if not provided in rules)
Chemical Composition( %):
|
Grade/ Material |
Element |
Composition( Max-A, Min-I) |
|
A387 Grade 12 Class 1/ A387 Gr12 Cl1 |
C |
0.05-0.17 |
|
Mn |
0.40-0.65 |
|
|
Si |
0.15-0.40 |
|
|
P |
0.035 |
|
|
S |
0.035 |
Mechanical Properties( Mpa)
|
Grade/ Material |
Tensile Test |
Ksi/MPa |
|
A387 Grade 12 Class 1/ A387 Gr12 Cl1 |
Tensile Strength |
55-80/380-550 |
|
Yield Strengh |
33/230 |
|
|
Elongation |
18% |
|
|
Impact Test( if any) |
|
Q1: What is the key alloying composition of ASTM A387 Grade 12 Class 1, and how does it differ from Grade 11?
Alloy System: 1.0% Cr-0.5% Mo (vs. 1.25% Cr-0.5% Mo in Grade 11)
Carbon Control: ≤0.15% (lower than Grade 11's ≤0.20%) for improved weldability
Manganese (Mn): 0.30–0.60% (balanced for strength and toughness)
*Purpose: Optimized for elevated-temperature hydrogen service with better formability than Grade 11.*
Q2: What are the mechanical property requirements for Grade 12 Class 1 plates?
| Property | Requirement | Test Standard |
|---|---|---|
| Tensile Strength | 415–585 MPa (60–85 ksi) | ASTM A370 |
| Yield Strength | ≥220 MPa (32 ksi) | ASTM A370 |
| Elongation (2") | ≥22% | ASTM A370 |
| Charpy Impact | 27J @ -30°C | ASTM A20 S5 (if specified) |
| *Note: Class 1 requires normalized + tempered condition, ensuring uniform microstructure.* |
Q3: Why is Grade 12 Class 1 preferred for hydrogen service in oil refineries?
Superior resistance to hydrogen embrittlement due to Cr-Mo carbides
Compliant with NACE MR0175/MR0103 for sour (H₂S) environments
Long-term creep resistance at ≤450°C (842°F)
Typical Applications:
Hydrotreater reactor shells
High-temperature hydrogen piping
Q4: What are the mandatory heat treatment and testing requirements?
Heat Treatment:
Normalizing: 900–940°C (1650–1725°F) for grain refinement
Tempering: 650–730°C (1200–1350°F) for stress relief and toughness
Testing Requirements:
Ultrasonic Testing (UT): ASTM A578 Level II (for thickness ≥6mm)
Charpy V-notch testing (if specified in purchase order)
Hardness Verification: Max 200 HB to avoid weld cracking
Q5: What welding procedures are recommended for Grade 12 Class 1?
Welding Best Practices:
Preheat: 150–200°C (300–400°F) for thickness >12mm
Consumables:
SMAW: AWS E8018-B2 (1.25Cr-0.5Mo) for matching properties
GTAW: ER80S-B2 filler metal
Post-Weld Heat Treatment (PWHT): 620–675°C (1150–1250°F) × 1h/25mm
Critical Note: Avoid prolonged exposure to 400–600°C (750–1110°F) to prevent temper embrittlement.
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