A662 grade C Chemical Composition
| A662 grade C Chemical Composition | |||||
| Grade | The Element Max (%) | ||||
| C | Mn | P | S | Si | |
| A662 grade C | 0.24 | 0.92-1.72 | 0.035 | 0.035 | 0.13-0.55 |
A662 grade C Mechanical Property
| Grade | A662 grade C Mechanical Property | |||
| Thickness | Yield | Tensile | Elongation | |
| A662 grade C | mm | Min Mpa | Mpa | Min % |
| 200 | 295 | 485-620 | 18 | |
| 50 | 22 | |||
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Additional Condition
UT(Ultrasonic examination), AR(As Hot Rolled only), TMCP(Thermal Mechanical Control Processing), N(Normalized), Q+T(Quenched and Tempered),Z Direction Test(Z15,Z25,Z35), Charpy V-Notch Impact Test, The Third Party Test (such as SGS Test), Coated or Shot Blasting and
Painting.
Q1: What is the minimum design metal temperature (MDMT) certification for A662 Grade C, and how does it compare to Grades A/B?
Certified Service Limits:
ASME Section VIII Div.1 approved for -120°C (vs Grade B's -101°C)
Charpy V-notch: ≥34J at -110°C (base metal) / ≥40J at -90°C (weld)
ISO 21009-3 compliance for LNG full-containment systems
Special Note: Requires fine grain practice (ASTM No. 8 or finer)
Q2: What is the nickel content range in Grade C, and how does it affect cryogenic performance?
Enhanced Alloy Chemistry:
Nickel: 1.50-2.00% (vs 0.80-1.20% in Grade B)
Ultra-low impurities: P≤0.010%, S≤0.008%
Micro-alloying: Ti (0.01-0.03%) + B (0.001-0.003%)
Metallurgical Advantages:
DBTT (Ductile-Brittle Transition Temp) <-150°C
Through-thickness Z-direction ψ ≥ 45%
Q3: What are the mandatory welding procedures for -196°C liquid nitrogen service?
LH2/LN2 Welding Protocol:
Preheat: 120-180°C (thermocouple-monitored)
Consumables: AWS A5.28 ER100S-Ni3 (5.5%Ni)
Interpass control: ≤100°C with ≤15kJ/cm heat input
Post-Weld Treatments:
Full PWHT at 600±10°C for 2hrs + Simulated Post-Weld Heat Treatment (SPWHT)
Phased Array UT + TOFD for thickness >30mm
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