ASTM A350 Grade LF2 Class 1 specification for forging Flanges,Fittings
ASTM A350 Grade LF2 Class 1 is a low-carbon steel material used for forged flanges, fittings, valves, and other pressure-containing parts operating in low-temperature service. It is commonly used in oil & gas, petrochemical, and cryogenic applications where impact toughness is required.
| Grade | A350 Grade LF2 Class 1 |
|---|---|
| Other Names | |
| Corresponding Standard | ASTM A350_A350M-23 Standard Specification for Carbon and Low-Alloy Steel Forgings, Requiring Notch Toughness Testing for Piping Components |
| Classification | Alloy Steel |
ASMT A350 Grade LF2 Class 1 Chemical Element Composition Content (%)
| Component | C | Si | Mn | P | S | Cr | Ni | Cu | Mo | V | Nb * | More |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Minimum Value | – | 0.15 | 0.6 | – | – | – | – | – | – | – | – | Cu+Ni+Cr+V+Mo≤ 1.00；Cr+Mo≤ 0.32 |
| Maximum Value | 0.3 | 0.3 | 1.35 | 0.035 | 0.04 | 0.3 | 0.4 | 0.4 | 0.12 | 0.08 | 0.02 |
A350 Grade LF2 Class 1 Mechanical Properties
| Heat Treatment or Condition | Tensile Strength σb Mpa |
Yield Point σs Mpa |
Elongation or Extension Rate δ % |
Reduction of Area ψ % |
Hardness HBW |
Impact Energy Absorption KV2 J |
|
|---|---|---|---|---|---|---|---|
| Forging | Heat Treatment | 485~655 | ≥250 | ≥22 | ≥30 | ≤197 | |
| Low Temperature -46°C | ≥20 |
Applications
- Low-temperature piping and pressure vessels
- Cryogenic equipment and LNG applications
- Oil & gas, petrochemical, and refinery industries
- Flanges, valves, and fittings for low-temperature service
Commonly Used for Flanges & Fittings
- Flanges: ASTM A350 LF2 Weld Neck, Slip-On, Blind, Threaded, Lap Joint, Socket Weld
- Fittings: Elbows, Tees, coupling, Caps ASME B16.11
Impact Test Temperature under ASTM A350 Flanges
Test Specimens by 10mm x 10mm
|
Grade |
Test Temperature, ℉ [℃] |
|---|---|
|
LF1 |
-20 [-29] |
|
LF2 Class 1 |
-50 [-46] |
|
LF2 Class 2 |
-0 [-18] |
|
LF3, Classes 1 and 2 |
-150 [-101] |
|
LF5, Classes 1 and 2 |
-75 [-59] |
|
LF6, Classes 1 and 2 |
-60 [-51] |
|
LF6 Class 3 |
0 [-18] |
|
LF9 |
-100 [-73] |
|
LF787 Class 2 |
-75 [-59] |
|
LF787 Class 3 |
-100 [-73] |
Impact test values: Charpy V-Notch Energy Requirements for specimens 10mm by 10mm.
|
Grade |
Minimum Impact Value for Average of 3 specimens, ft-lbf [J] |
Minimum Impact Value for One Specimen, ft-lbf [J] |
|---|---|---|
|
LF1 and LF9 |
13 [18] |
10 [14] |
|
LF2 Class 1 |
15 [20] |
12 [16] |
|
LF3 Class 1 |
15 [20] |
12 [16] |
|
LF5 Class 1 and 2 |
15 [20] |
12 [16] |
|
LF787 Classes 2 and 3 |
15 [20] |
12 [16] |
|
LF6 Class 1 |
15 [20] |
12 [16] |
|
LF2 Class 2 |
20 [27] |
15 [20] |
|
LF3 Class 2 |
20 [27] |
15 [20] |
|
LF6 Classes 2 and 3 |
20 [27] |
15 [20] |
Referenced Documents
ASTM Standards:
- A788/A788M Specification for Steel Forgings, General Requirements
- A961/A961M Specification for Common Requirements for Steel Flanges, Forged Fittings, Valves, and Parts for Piping Applications
ASME Standards:
- B 16.5 Steel Pipe Flanges and Flanged Fittings
- B 16.9 Factory-Made Wrought Steel Butt-Welding Fittings
- B 16.10 Face-to-Face and End-to-End Dimensions of Ferrous Valves
- B 16.11 Forged Steel Fittings, Socket-Welding and Threaded
- B 16.30 Unfired Pressure Vessel Flange Dimensions
- B 16.34 Valves-Flanged, Threaded, and Welding End
- B 16.47 Large Diameter Steel Flanges
- ASME Boiler and Pressure Vessel Code
AWS Standards:
- A 5.1 Mild Steel Covered Arc-Welding Electrodes
- A 5.5 Low-Alloy Steel Covered Arc-Welding Electrodes
API Standards:
- 600 Steel Gate Valves with Flanged or Butt-Welding Ends
- 602 Compact Design Carbon Steel Gate Valves for Refinery Use
- 605 Large Diameter Carbon Steel Flanges
Manufacture – Melting and Forging
Melting Process – The steel shall be produced by any of the following primary processes: open-hearth, basic oxygen, electric-furnace, or vacuum-induction melting (VIM). The primary melting may incorporate separate degassing or refining, and may be followed by secondary melting using electroslag remelting (ESR), or vacuum-arc remelting (VAR).
Discard – A sufficient discard shall be made to secure freedom from injurious piping and undue segregation.
Forging Process
Material for forgings shall consist of ingots, or forged, rolled, or strand cast blooms, billets, slabs, or bars.
Heat Treatment
After hot working and before reheating for heat treatment, the forging shall be allowed to cool substantially below the transformation range.
Forgings grades except Grade LF787, should be heat treated in normalized, or normalized and tempered, or quenched and tempered. By manufacturer’s option, material that performed in quenched and tempered could be normalized prior to the austenitize/quenched operation.
No limitation on size is intended beyond the ability of the manufacturer to obtain the specified requirements. However, Class 3 of Grade LF787 is only available in the quenched-and-precipitation heat treated condition.