ASTM A350 LF2 Carbon Steel Fittings – A350 Gr LF2 Low-Temperature Forged Fittings
ASC LLP, Mumbai, supplies ASTM A350 LF2 fittings: low-temperature forged socket-weld and threaded fittings to ASME B16.11, together with branch outlets, in Class 1 and Class 2. In addition, every fitting comes with an EN 10204 3.1 certificate that includes the Charpy impact results. See also our full range of carbon steel fittings.
What is ASTM A350 LF2 Material?
ASTM A350 (ASME SA350) is the specification for carbon and low-alloy steel forgings that require notch toughness testing, for piping components in low-temperature service. In the grade name, “L” stands for low temperature and “F” for forged. LF2 is the carbon-manganese grade, so it has the same strength as A105 but is Charpy impact tested. As a result, LF2 can be used in cold service where A105 would risk brittle fracture.
LF2 is supplied in two classes. Class 1 is impact tested at −46 °C (−50 °F), whereas Class 2 is tested at −32 °C (−25 °F) with a higher energy requirement. For this reason, always state the class on the order, for example “A350 LF2 Cl.1”.
A350 LF2 – Quick Facts
- Specification: ASTM A350 / ASME SA350, Grade LF2 Class 1 or 2
- Material: forged carbon-manganese steel, then heat treated
- Strength: 485–655 MPa tensile / 250 MPa yield min
- Impact test: −46 °C (Class 1) or −32 °C (Class 2)
- Fittings standard: ASME B16.11, while outlets follow MSS SP-97
- Matching pipe: ASTM A333 Grade 6, so the whole line is impact tested
ASTM A350 LF2 Chemical Composition
| Element | A350 LF2 (%) |
| Carbon (C) | 0.30 max |
| Manganese (Mn) | 0.60 – 1.35 |
| Phosphorus (P) | 0.035 max |
| Sulphur (S) | 0.040 max |
| Silicon (Si) | 0.15 – 0.30 |
| Nickel (Ni) | 0.40 max |
| Chromium (Cr) | 0.30 max |
| Molybdenum (Mo) | 0.12 max |
| Copper (Cu) | 0.40 max |
| Vanadium (V) | 0.08 max |
| Niobium (Nb) | 0.02 max |
In addition, two combined limits apply: Cu + Ni + Cr + V + Mo must not exceed 1.00%, and Cr + Mo must not exceed 0.32%. However, if vacuum carbon-deoxidation is used, silicon may be limited to 0.12% max instead.
A350 LF2 Material – Mechanical Properties
| Property | A350 LF2 (Class 1 & 2) |
| Tensile strength | 485 – 655 MPa (70 – 95 ksi) |
| Yield strength, min | 250 MPa (36 ksi) |
| Elongation, min | 22% |
| Hardness, max | 197 HBW, which also helps weldability |
Both classes have the same tensile requirements. By contrast, they differ only in the Charpy impact test, which is the main reason for choosing LF2.
A350 LF2 Class 1 vs Class 2 – Impact Test
| Requirement | LF2 Class 1 | LF2 Class 2 |
| Test temperature | −46 °C (−50 °F) | −32 °C (−25 °F) |
| Average of 3 specimens, min | 20 J (15 ft·lbf) | 27 J (20 ft·lbf) |
| Single specimen, min | 16 J (12 ft·lbf) | 20 J (15 ft·lbf) |
In short, Class 1 is tested colder, while Class 2 needs more energy at a slightly higher temperature. Therefore, choose the class that matches the minimum design metal temperature in your piping specification.
A350 LF2 vs A105
| Feature | A350 LF2 | A105 |
| Charpy impact test | Mandatory (−46 °C for Class 1) | Not required (only by supplementary S5) |
| Minimum design temperature | About −46 °C (Class 1) | About −29 °C without impact testing |
| Tensile / yield | 485–655 / 250 MPa | 485 min / 250 MPa |
| Carbon, max | 0.30% | 0.35% |
| Cost | Higher, because of testing and heat treatment | Lower, since no impact test is needed |
Both grades have similar strength. However, LF2 is chosen for toughness, for example in cold climates, LNG plants or lines that can autorefrigerate during depressurisation. For colder service still, A350 LF3 (3½% nickel) is used instead.
A350 LF2 Forged Fittings – ASME B16.11 Classes & Sizes
| Fitting type | 2000# | 3000# | 6000# | 9000# |
| Socket-weld fittings | – | ⅛ – 4″ (SCH 80) | ⅛ – 2″ (SCH 160) | ½ – 2″ (XXS) |
| Threaded fittings | Up to 4″ (SCH 80) | ⅛ – 4″ (SCH 160) | Up to 2″ (XXS) | – |
We supply socket-weld and threaded elbows, tees, couplings, caps, unions, plugs, bushings and swage nipples, as well as Weldolets and Sockolets. By contrast, low-temperature buttweld elbows, tees and reducers are ordered as A420 WPL6 fittings, and flanges as A350 LF2 flanges.
ASTM A350 LF2 Fittings Specifications
| Item | Details |
| Specification | ASTM A350 / ASME SA350, Grade LF2 Class 1 or 2 |
| Fitting standard | ASME B16.11; MSS SP-97 for outlets; also MSS SP-83 for unions |
| Pressure class | 2000, 3000, 6000 and 9000, depending on the pipe schedule |
| Size | NPS ⅛ to 4; however, the range depends on class |
| Heat treatment | Normalised, normalised and tempered, or quenched and tempered (590 °C min temper) |
| Testing | Chemistry, tensile, hardness and Charpy; in addition, PMI and third-party inspection on request |
| Certificate | EN 10204 3.1; also 3.2 on request |
A350 LF2 Fittings – Matching Low-Temperature Grades
| Component | Matching low-temperature grade |
| Seamless pipe | ASTM A333 Grade 6, because it is also impact tested |
| Buttweld fittings | ASTM A420 WPL6 for larger sizes |
| Flanges | ASTM A350 LF2 flanges |
| Stud bolts / nuts | ASTM A320 L7 with A194 Gr 4 or 7 (impact tested) |
Because the whole line must resist brittle fracture, every component should be impact tested to the same design temperature. In other words, an LF2 fitting on A333 Grade 6 pipe should be bolted with A320 L7 rather than A193 B7.
Applications of ASTM A350 LF2 Fittings
| Industry | Typical A350 LF2 fitting use |
| LNG & gas processing | Cold-service piping, as well as lines that can autorefrigerate |
| Refrigeration & ammonia | Chiller and refrigeration piping, while temperatures stay above −46 °C |
| Petrochemical | Ethylene and propylene plants, for example in cold-end sections |
| Cold-climate oil & gas | Outdoor piping in regions with very low ambient temperatures |
LF2 is plain carbon-manganese steel, so it is chosen for toughness rather than corrosion resistance. Therefore, corrosive service still needs coatings or stainless steel. For general ambient service, see also A105 and A234 WPB fittings and our carbon steel products.
Why Buy A350 LF2 Fittings from ASC LLP?
- Impact-tested material: 3.1 certificates with Charpy results, so the class and test temperature are clear.
- Complete low-temperature packages: fittings together with A333 Gr 6 pipe, WPL6 fittings, LF2 flanges and L7 bolting.
- Correct grade advice: help choosing LF2 Class 1 or 2, A105 or LF3, because design temperature decides the grade.
- Inspection: PMI, hardness checks and, in addition, third-party inspection on request.
Frequently Asked Questions – ASTM A350 LF2 Fittings
What is ASTM A350 LF2 material?
ASTM A350 LF2 is a forged carbon-manganese steel that is Charpy impact tested for low-temperature service. It is used for forged fittings, flanges and valve parts in cold piping.
What is the chemical composition of A350 LF2?
LF2 contains C 0.30% max, Mn 0.60–1.35%, Si 0.15–0.30%, P 0.035% max and S 0.040% max. In addition, Ni, Cr, Mo, Cu, V and Nb are limited, with Cu + Ni + Cr + V + Mo ≤ 1.00%.
What are the mechanical properties of A350 LF2?
Tensile strength is 485–655 MPa (70–95 ksi), yield is 250 MPa (36 ksi) min, elongation is 22% min and hardness is 197 HBW max.
What is the difference between LF2 Class 1 and Class 2?
Class 1 is impact tested at −46 °C (−50 °F) to 20 J average. By contrast, Class 2 is tested at −32 °C (−25 °F) to 27 J average.
What is the difference between A350 LF2 and A105?
Both have similar strength. However, LF2 must pass a Charpy impact test, so it can be used down to about −46 °C, whereas A105 is limited to about −29 °C without impact testing.
Which pipe is used with A350 LF2 fittings?
LF2 fittings are normally used with ASTM A333 Grade 6 low-temperature pipe, together with A420 WPL6 buttweld fittings.
What does LF2 stand for?
“L” stands for low temperature and “F” for forged, while “2” is the grade number within ASTM A350.
Global Supply
ASC LLP supplies ASTM A350 LF2 fittings from Mumbai to customers in India, the Middle East, Europe, Africa, the Americas and South-East Asia. To get a prompt quotation, simply send your enquiry with fitting type, size, B16.11 class, LF2 class and quantity.
Countries We Export To
UNITED STATES, EUROPE, UK, UAE, SAUDI ARABIA, OMAN, KUWAIT, JORDAN, QATAR, INDONESIA, MALAYSIA, BRAZIL, SPAIN, ITALY, FRANCE, GERMANY, BAHRAIN, SRI LANKA, AZERBAIJAN, AUSTRALIA, AUSTRIA, PHILIPPINES, TURKEY, RUSSIA, IRAN, IRAQ, CANADA, KOREA, JAPAN, YEMEN, FINLAND, ZIMBABWE, HUNGARY, PORTUGAL, VIETNAM, MOROCCO, THAILAND, SOUTH AFRICA, MEXICO, SINGAPORE, GREECE, KUWAIT, POLAND, NEW ZEALAND, SWEDEN, SWITZERLAND, BELGIUM, BHUTAN, BANGLADESH, TAIWAN, ROMANIA, CAMBODIA, KAZAKHSTAN, AFGHANISTAN.
