ASTM A350 / ASME SA350 LF2 Alloy Steel Forged Flange B16.5 for Low Temperature
ASTM A350 is a standard specification for carbon steel and low-alloy steel forgings used for notch toughness testing of pipeline components. This specification covers various products such as forged or ring rolled flanges, forged fittings, and valves made of carbon steel and low-alloy steel, and is particularly suitable for low-temperature environments such as LNG facilities, cold storage, and polar engineering. And a notch toughness test is required. These products are manufactured according to specified dimensions or comply with the size standards specified in the standards.
The core advantages of ASTM A350 LF2 alloy steel flanges mainly focus on three aspects: low-temperature toughness, welding performance, and corrosion resistance. ASTM A350 LF2 alloy steel flanges can pass rigorous impact testing (-46 ° C) to ensure resistance to brittle fracture at low temperatures. Additionally, due to their low carbon content, typically ≤ 0.45, they are easy to weld. The trace alloying elements (such as nickel) in the chemical composition of ASTM A350 LF2 can enhance its adaptability to low-temperature corrosive environments.
ASTM A350 Chemical Composition
| GRA. | CHEMICAL COMPOSITION % MAXIMUM
|
| C | MN | P | S | SI | CR | NI | MO | CU | CO | VA |
| LF1 | 0.30 | 0.60-1.35 | 0.035 | 0.04 | 0.15-0.30 | 0.30 | 0.40 | 0.12 | 0.40 | 0.02 | 0.08 |
| LF2 | 0.30 | 0.60-1.35 | 0.035 | 0.04 | 0.15-0.30 | 0.30 | 0.40 | 0.12 | 0.40 | 0.02 | 0.08 |
| LF3 | 0.20 | 0.90 | 0.035 | 0.04 | 0.20-0.35 | 0.30 | 3.3-3.7 | 0.12 | 0.40 | 0.02 | 0.03 |
ASTM A350 TENSILE PROPERTIES AT ROOM TEMPERATURE
| GRA. | Tensile Strength, min, ksi [MPa] | Yield Strength, min, ksi [MPa]B |
| LF1 | 60-85[415-585] | 30[205] |
| LF2 | 70-95[485-655] | 36[250] |
| LF3 | 70-95[485-655] | 37.5[260] |
Processing and Manufacturing Requirement
- Forging process: ASTM A350 LF2 alloy steel forged flanges require forging to improve material density and eliminate casting defects.
- Heat treatment: ASTM A350 LF2 alloy steel forged flanges require normalizing or normalizing+tempering to refine grain size and enhance toughness.
- Non destructive testing: ASTM A350 LF2 alloy steel forged flanges require ultrasonic testing (UT) or magnetic particle testing (MT) to ensure no cracks or inclusions.
Application:
- Liquefied natural gas (LNG) industry: The low-temperature toughness (-46 ° C) of ASTM A350 LF2 can prevent its occurrence of low-temperature brittle fracture, ensuring the safety of LNG transportation at ultra-low temperatures (-162 ° C). Therefore, ASTM A350 LF2 alloy steel forged flanges can be used as pump flanges, low-temperature valve connection flanges, and other components in LNG storage tanks, liquefied natural gas transportation pipelines, and re gasification terminal equipment.
- Petrochemical and Refining: The low-temperature corrosion resistance and high-pressure capability of ASTM A350 LF2 make it suitable for processing liquefied hydrocarbons (such as propane and butane) and low-temperature chemical reaction pipelines. Therefore, ASTM A350 LF2 alloy steel forged flanges can be used as low-temperature separator flanges, compressor inlet and outlet flanges, and other components in low-temperature separation units, ethylene cracking units, liquid nitrogen/liquid oxygen storage and transportation systems.
- Marine and Polar Engineering: ASTM A350 LF2 alloy steel forged flange has good cold resistance, adapts to extremely low temperature environments, and has excellent resistance to seawater corrosion. Therefore, it can be used as a connecting component in polar ships, offshore oil platforms, and oil pipelines within the Arctic Circle.
- Energy and Power: The high strength and impact toughness of ASTM A350 LF2 alloy steel forged flange can meet the requirements of nuclear safety and high-pressure hydrogen transportation. Therefore, it can be used as a typical component for cooling systems in nuclear power plants, low-temperature pipelines in natural gas power plants, nuclear grade pump valve flanges in liquid hydrogen energy facilities, and connection flanges for liquid hydrogen storage tanks.
- Chemical and specialty gases: ASTM A350 LF2 alloy steel forged flange has low-temperature corrosion resistance and high-pressure sealing performance, which can ensure the safe transportation of toxic or flammable media. Therefore, ASTM A350 LF2 alloy steel forged flange can be used as a flange for liquid ammonia storage tanks, high-pressure gas valves, etc. in liquid ammonia storage and transportation systems, carbon dioxide compression devices, and specialty gas (such as argon and helium) pipeline systems.
