ASTM A350 LF2 Flanges are forged carbon steel flanges engineered for low-temperature service, ideal for oil, gas, and cryogenic applications. Compliant with ASTM A350 LF2, they excel in cold environments. As of August 22, 2025, 07:13 PM PDT, they are a top choice.

These Low-Temperature Flanges range from 1/2” to 48” in size, with pressure ratings up to 2000 PSI and temperature tolerance down to -50°C. They ensure performance in harsh winter conditions.

ASTM A350 LF2 Flanges undergo tensile, impact, and hydrostatic testing for reliability. Coatings like galvanizing enhance corrosion resistance, making them suitable for cryogenic pipelines as of August 2025.

Compared to standard carbon steel, ASTM A350 LF2 Flanges offer superior toughness at low temperatures, with a service life of 15–35 years with proper maintenance, balancing durability and cost.

ASTM A350 LF2 Flanges address challenges like brittle failure and cold-weather leaks in industrial piping, ensuring safety as of August 22, 2025.

ASTM A350 covers several grades of carbon and low-alloy steel forged or ring-rolled flanges, forged fittings and valves intended primarily for low-temperature service and requiring notch toughness testing. They are made to specified dimensions, or to dimensional standards, such as the ASME and API Specifications referenced in Section 2. Although this specification covers some piping components machined from rolled bar and seamless tubular materials, it does not cover raw material produced in these product forms.

Product furnished in ASTM A350/ ASME SA350 shall conform to the requirements of Specification A961/A961M, including any supplementary requirements that are indicated in the purchase order. Failure to comply with A961/A961M will be considered nonconformance with A350. And in case of conflict between ASTM A350 and A961/A961M, this specification shall prevail.

Composition of ASTM A350 LF2 Flange Material
Element	Percentage (%)	Function
Carbon (max)	0.30	Enhances strength and hardness
Manganese (max)	0.60–1.35	Improves toughness at low temperatures
Phosphorus (max)	0.035	Reduces brittleness
Sulfur (max)	0.040	Enhances machinability
Silicon (max)	0.15–0.35	Increases strength and elasticity

ASTM A350 LF2 Flanges utilize this composition to ensure performance in low-temperature conditions.

*The sum of Cu, Ni, Cr, V, and Mo shall not exceed 1.00% on heat analysis. The sum of Cr and Mo shall not exceed 0.32% on heat analysis. By agreement, the limit for Nb may be increased up to 0.05 % on heat analysis and 0.06 % on product analysis. The carbon equivalent CE = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15. For both Class 1 and Class 2 of ASTM A350 LF2, if the maximum thickness of the work piece is less than or equal to 2″, the CE shall not exceed 0.47; if the the maximum thickness of the work piece is greater than 2″, the CE shall not exceed 0.48.

Properties of ASTM A350 LF2 Flange Material
Property	Value	Test Standard
Tensile Strength (min)	485–655 MPa	ASTM A370
Yield Strength (min)	250 MPa	ASTM A370
Elongation (min)	22%	ASTM E8
Hardness (Brinell)	137–187 HB	ASTM E10
Impact Toughness (min)	20 J at -46°C	ASTM E23
Temperature Range	-50°C to 400°C	N/A

These properties make ASTM A350 LF2 Flanges a reliable choice for low-temperature and cryogenic applications.

Comparison of ASTM A350 LF2 with Other Flange Standards
Standard	Material	Yield Strength (min)	Temperature Range	Key Advantage
ASTM A350 LF2	Forged Carbon Steel	250 MPa	-50°C to 400°C	Low-Temperature Toughness
ASTM A105	Forged Carbon Steel	250 MPa	-20°C to 425°C	High-Temperature Durability
ASTM A694	High-Yield Carbon/Alloy	290–485 MPa	-20°C to 500°C	High-Pressure Strength
ASTM A182	Stainless/Alloy Steel	205–310 MPa	-20°C to 600°C	Corrosion Resistance

ASTM A350 LF2 Flanges excel in low-temperature toughness, while A105 suits high temperatures, A694 handles high pressures, and A182 offers corrosion resistance as of August 22, 2025.

Mechanical & Service Properties of ASTM A350 LF2 Flange Material (Low-Temperature Carbon Steel)
Property Category	Technical Value	Test/Reference Standard
Tensile Strength (Minimum)	485–655 MPa (Megapascal)	ASTM A370 (Standard for Tension Testing of Steel Products)
Yield Strength (0.2% Offset, Minimum)	250 MPa (Megapascal)	ASTM A370 (Standard for Tension Testing of Steel Products)
Elongation (in 50mm Gauge Length, Minimum)	22%	ASTM E8 (Standard for Tension Testing of Metallic Materials)
Brinell Hardness (HB)	137–187 HB (3000kgf Load, 10mm Ball)	ASTM E10 (Standard for Brinell Hardness Testing of Metallic Materials)
Impact Toughness (Minimum)	20 J (Joule) at -46°C (Charpy V-Notch)	ASTM E23 (Standard for Notched Bar Impact Testing of Metallic Materials)
Continuous Service Temperature Range	-50°C to 400°C	N/A (Derived from material composition & industrial application data)

ASTM A350/ASME SA350 Grade Impact Toughness Requirements (Charpy V-Notch Test)
Grade / Class	Minimum Impact Value (Average of 3 Specimens) ft-lbf [J]	Minimum Impact Value (Single Specimen) ft-lbf [J]
LF1 LF9	13 [18]	10 [14]
LF2 Class 1 LF3 Class 1 LF5 Class 1 & 2 LF787 Class 2 & 3 LF6 Class 1	15 [20]	12 [16]
LF2 Class 2 LF3 Class 2 LF6 Class 2 & 3	20 [27]	15 [20]

Key Explanations

• Test Basis: Values are based on the Charpy V-Notch (CVN) impact test, compliant with ASTM E23 standard, evaluating material toughness to resist brittle fracture at low temperatures.
• Unit Interpretation: ft-lbf (foot-pound-force) is the imperial unit, [J] (Joule) is the metric unit, ensuring compatibility with global engineering standards.
• Grouping Logic: - Normal rows (LF1/LF9): Lowest impact toughness, suitable for mild low-temperature conditions; - Light gray rows: Medium toughness, for general low-temperature service; - Blue rows (LF2 Class 2/LF3 Class 2/LF6 Class 2-3): Highest toughness, for strict low-temperature scenarios (e.g., cryogenic pipelines, cold-region equipment).
• Acceptance Criteria: Both "3-specimen average" and "single specimen" values must be met—no individual specimen can be lower than the single-specimen minimum, even if the average is satisfied.