ASTM A350 LF2 CL1 Girth Flanges NPS 1/2" to 24" Class 150 to 2500#
1. Introduction to ASTM A350 LF2 Class 1 Girth Flanges
ASTM A350 LF2 Class 1 Girth Flanges are forged carbon/low-alloy steel fittings designed for low-temperature service down
to -46°C (-50°F). These flanges meet stringent impact toughness requirements (Charpy V-notch testing) for cryogenic
applications in pipelines, LNG plants, and offshore systems. Manufactured in compliance with ASME B16.5 dimensional
standards, they ensure leak-proof connections in high-pressure environments.
2. Chemical Composition Requirements
The chemical composition of ASTM A350 LF2 CL1 ensures optimal low-temperature performance and weldability:
| Element | Composition (% Max) | Key Function |
|---|---|---|
|
Carbon (C) |
0.30% |
Strength & Hardness |
|
Manganese (Mn) |
0.60-1.35% |
Toughness Enhancer |
|
Phosphorus (P) |
0.035% |
Weldability Control |
|
Sulfur (S) |
0.040% |
Machinability |
|
Silicon (Si) |
0.15-0.30% |
Deoxidizer |
|
Nickel (Ni) |
0.40% Max |
Low-Temp Toughness |
3. Mechanical Properties of LF2 CL1 Flanges
|
Property |
Requirement |
Test Standard |
|---|---|---|
|
Tensile Strength |
485-655 MPa (70-95 ksi) |
ASTM A370 |
|
Yield Strength (Min) |
250 MPa (36 ksi) |
ASTM A370 |
|
Elongation (Min) |
22% |
ASTM A370 |
|
Impact Toughness |
Avg. ≥ 20 J (15 ft-lbf) |
ASTM A370 |
4. Equivalent Grades & International Standards
|
Standard |
Equivalent Grade |
Key Differences |
|---|---|---|
|
EN 10222 |
P355NH (1.0566) |
Higher Ni allowance (≤1.0%) |
|
NACE MR0175 |
Compliant |
H₂S service approved |
|
JIS G3202 |
SFVQ2A |
Similar impact values |
5. Key Applications in Industry
ASTM A350 LF2 CL1 flanges are critical in:
- Cryogenic Systems: LNG terminals, liquid nitrogen pipelines
- Oil & Gas: Subsea pipelines, Arctic drilling rigs
- Power Plants: Cooling systems, hydrogen handling
- Chemical Processing: Ethylene, ammonia, and propane transport
6. Manufacturing & Quality Assurance
- Process: Die-forged & heat-treated (normalized or quenched + tempered)
- Testing: 100% UT + hydrostatic testing per ASME B16.34
- Certification: Mill Test Reports (MTRs) with traceable heat numbers
- Dimensions: ASME B16.5 Class 150 to 2500, NPS 1/2" to 24"
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