ASTM A350 LF2 CL1 Slip-On Flange | LTCS SORF ASME B16.5
ASTM-A-350LF2 Class 1 Slip-On Flanges (SORF) are forged low-temperature carbon steel (LTCS) flanges designed for pressure piping systems operating in sub-zero temperature environments. Manufactured in accordance with ASME B16.5, LF2 CL1 slip-on raised face flanges provide a reliable, economical and easy-to-install flange solution for low-temperature service applications.
ASTM A350 LF2 CL1 flanges are widely used in LNG plants, offshore platforms, petrochemical facilities, refineries and low-temperature process piping systems where notch toughness and impact resistance are critical.
We are a professional manufacturer and exporter of ASTM A350 LF2 CL1 Slip-On Raised Face (SORF) Flanges in China, supplying ASME B16.5 forged LTCS flanges for global industrial projects.
What is ASTM A350 LF2 Class 1?
ASTM A350 / ASME SA350 covers forged carbon and low-alloy steel flanges, fittings and valves intended primarily for low-temperature service applications requiring notch toughness testing.
ASTM A350 LF2 is one of the most commonly used low-temperature carbon steel materials for forged flanges due to its:
- excellent low-temperature toughness
- reliable weldability
- stable mechanical properties
- cost-effective performance
LF2 material is widely specified for piping systems exposed to sub-zero operating conditions.
Slip-On Raised Face (SORF) Flange Design
Slip-On Raised Face (SORF) flanges are designed to slide over the pipe and are connected using fillet welds on both the inside and outside of the flange.
For low-temperature piping systems where installation efficiency and cost control are important, ASTM A350 LF2 CL1 SORF flanges provide a practical solution.
Features of SORF Flanges
- easy pipe alignment
- simple installation
- lower fabrication cost
- suitable for low and medium pressure systems
- reduced machining requirements
Slip-on flanges are commonly used in systems with:
- lower pressure service
- moderate temperature conditions
- minimal leakage risk
They may be manufactured with or without hubs depending on project specifications.
ASTM A350 LF2 Class 1 vs Class 2
ASTM A350 LF2 Class 1 and Class 2 have similar chemical composition and mechanical properties. The primary difference between the two grades is the minimum impact test temperature requirement.
| Grade | Minimum Test Temperature |
|---|---|
| LF2 Class 1 | −50°F [−46°C] |
| LF2 Class 2 | −0°F [−18°C] |
The minimum applicable temperature is also the standard Charpy V-notch impact test temperature.
In practical applications, ASTM A350 LF2 Class 1 is generally selected for lower temperature service conditions compared with LF2 Class 2.
ASTM A350 LF2 Chemical Composition
ASTM A350 LF2 chemical composition is carefully controlled to provide low-temperature toughness and good weldability.
| Element | Composition (%) |
|---|---|
| Carbon (C) | ≤ 0.30 |
| Manganese (Mn) | 0.60 – 1.35 |
| Phosphorus (P) | ≤ 0.035 |
| Silicon (Si) | 0.15 – 0.30 |
| Sulfur (S) | ≤ 0.040 |
Low carbon content helps improve weldability and impact toughness in low-temperature environments.
ASTM A350 LF2 Mechanical Properties
ASTM A350 LF2 forged flanges provide stable mechanical properties for low-temperature piping applications.
| Property | Requirement |
|---|---|
| Tensile Strength | 485 – 655 MPa |
| Yield Strength | 250 MPa Minimum |
| Elongation | ≥ 22% |
These mechanical properties make LF2 flanges suitable for pressure piping systems requiring reliable toughness and ductility.
ASTM A350 LF2 Heat Treatment Condition
ASTM A350 Grade LF2 forged flanges are commonly supplied in the following heat treatment conditions:
- Normalized
- Normalized and Tempered
- Quenched and Tempered
Proper heat treatment improves:
- notch toughness
- grain structure
- low-temperature impact resistance
- mechanical consistency
ASTM A350 LF2 Charpy V-Notch Impact Requirements
Minimum Impact Energy Requirements for Standard Size Specimens [10 × 10 mm]
| Grade | Average of 3 Specimens | One Specimen Minimum |
|---|---|---|
| LF2 Class 1 | 15 ft-lbf [20 J] | 12 ft-lbf [16 J] |
| LF2 Class 2 | 20 ft-lbf [27 J] | 15 ft-lbf [20 J] |
Standard Impact Test Temperature
| Grade | Test Temperature |
|---|---|
| LF2 Class 1 | −50°F [−46°C] |
| LF2 Class 2 | −0°F [−18°C] |
Charpy impact testing ensures the flange material maintains toughness under low-temperature operating conditions.
ASTM A350 LF2 CL1 Slip-On Flange Specification
| Specification | Details |
|---|---|
| Material Standard | ASTM A350 / ASME SA350 |
| Grade | LF2 Class 1 |
| Flange Type | Slip-On Raised Face (SORF) |
| Flange Standard | ASME B16.5 |
| Additional Standard | ASME B16.47 |
| Material Type | LTCS Forged Carbon Steel |
| Facing Types | RF / FF / RTJ |
| Pressure Classes | 150, 300, 400, 600, 900, 1500, 2500 |
Available Sizes and Wall Thickness
Size Range
- 1/2”
- 1”
- 2”
- 3”
- 4”
- 6”
- 8”
- 10”
- 12”
- 16”
- 20”
- 24”
- 36”
- 48”
Available Pipe Schedules
- SCH STD
- SCH 40
- SCH 80
- SCH XS
- SCH XXS
- SCH 100
- SCH 160
Custom dimensions are available upon request.
Flange Facing Types
Raised Face (RF)
The most common flange facing for industrial piping systems.
Flat Face (FF)
Used for low-pressure piping systems and cast iron equipment connections.
Ring Type Joint (RTJ)
Suitable for high-pressure and critical sealing applications.
Applications of ASTM A350 LF2 CL1 Slip-On Flanges
ASTM A350 LF2 CL1 LTCS SORF flanges are widely used in:
- LNG plants
- offshore platforms
- petrochemical facilities
- low-temperature process piping
- cryogenic systems
- refinery piping
- natural gas pipelines
- pressure vessel connections
Their excellent low-temperature impact toughness makes them suitable for severe cold service environments.
Inspection and Testing
ASTM A350 LF2 CL1 flanges can be supplied with:
- PMI Testing
- Ultrasonic Testing (UT)
- Hardness Testing
- Charpy Impact Testing
- Dimensional Inspection
- EN 10204 3.1 Certification
Third-party inspection is available upon request.
Related Products
Low Temperature Carbon Steel Flanges
- ASTM A350 LF2 Blind Flange
- ASTM A350 LF2 Weld Neck Flange
- ASTM A350 LF2 Socket Weld Flange
Carbon Steel Flanges
- ASTM A105 Slip-On Flange
- ASTM A105 Blind Flange
Why Choose Our ASTM A350 LF2 CL1 SORF Flanges?
We provide:
- full material traceability
- strict quality inspection
- low-temperature impact testing
- custom dimensions
- fast delivery
- third-party inspection support
- worldwide export service
Our ASTM A350 LF2 CL1 Slip-On Raised Face flanges are manufactured according to international piping standards for reliable low-temperature industrial performance.
