What Is ASTM A350 LF2?
ASTM A350 is the specification for carbon and low-alloy steel forgings requiring notch-toughness testing for piping applications. Grade LF2 is the workhorse low-temperature carbon steel forging — it is impact tested (Charpy V-notch) so flanges and fittings stay tough in cold service.
Temperature Range
LF2 is rated from -46°C to 425°C in the ASME B16.5 Group 1.1 pressure-temperature tables (verified on our live B16.5 flange page). For colder limits, higher nickel grades such as LF3 (3.5% Ni) are specified.
Material Group (per ASME B16.5)
A350 Gr. LF2 (C-Mn-Si) belongs to Material Group 1.1 of ASME B16.5 Table 1A, sharing pressure-temperature ratings with A105 and A516 Gr. 70.
Corrosion Resistance
As a carbon steel, LF2 has the same corrosion behavior as A105: good in neutral, alkaline and dry service; not recommended in acids or corrosive aqueous media (Schweitzer Corrosion Resistance Tables, Part A). Coat or paint for exposed atmospheric service.
Typical Applications
- ASME B16.5 flanges for low-temperature and winter pipelines
- ASME B16.11 socket-welding and threaded fittings for cold service
- Flanges and fittings in oil & gas, refinery and cryogenic-adjacent service above -46°C
Chemistry & Mechanical Properties
Composition, tensile/yield strength, hardness and Charpy impact acceptance values are defined in ASTM A350 / A370 — consult the standard for limits. Each batch ships with impact test reports and EN 10204 3.1 certification.
Related Standards
- ASME B16.5 — Pipe Flanges (NPS 1/2–24)
- ASME B16.11 — Socket-Welding & Threaded Fittings
- ASME B16.47 — Large-Diameter Flanges (NPS 26–60)
- ASTM A105 — Carbon Steel Forgings
- ASTM A420 WPL6 — Low-Temperature Fittings
- Our Flange Range
FAQ
What temperature range does LF2 cover?
-46°C to 425°C per the ASME B16.5 Group 1.1 tables.
What is the difference between A105 and LF2?
A105 is general-purpose carbon steel; LF2 adds Charpy V-notch impact testing for low-temperature toughness. Use LF2 whenever the design temperature drops below about -29°C or notch toughness is required.
Is LF2 suitable for -100 C (cryogenic) service?
No. LF2 is certified down to -46°C. Colder service requires 3.5% Ni steel (A350 LF3) or austenitic stainless grades.
What impact test is required?
Charpy V-notch testing per ASTM A370 with acceptance criteria per the ASTM A350 specification; test certificates ship with the goods.
What is the difference between LF2 and LF3?
LF2 is carbon-steel low-temperature forgings rated to -46°C. LF3 adds 3.5% nickel for colder service; both sit in ASME B16.5 Group 1.1.
Need This Standard for Your Project?
We manufacture and export flanges, fittings and gaskets to ASME standards. Send your standard, size, material, and quantity — we reply within 24 hours.