ASME SA350 LF2 Class 1 Blind Flange | ASME B16.5

ASTM A350 LF2 blind flanges are forged low-temperature carbon steel flanges designed to close the end of pressure piping systems, valves, or pressure vessel nozzles.
Manufactured in accordance with ASME B16.5, these blind flanges are available in pressure classes from Class 150 to Class 2500, making them suitable for both low-temperature and high-pressure applications.

LF2 blind flanges are widely used in oil & gas, LNG, petrochemical, and low-temperature processing facilities

What Is ASTM A350 LF2?

ASTM A350 is a standard specification covering forged carbon and low-alloy steel flanges and fittings intended for low-temperature service.
LF2 is the most commonly specified grade under ASTM A350 and is qualified by mandatory Charpy V-notch impact testing.

ASTM A350 LF2 flanges are typically supplied in the normalized or normalized and tempered condition to ensure consistent mechanical properties and excellent low-temperature toughness.

Chemical Composition (Typical – ASTM A350 LF2)

Mechanical Properties

Impact testing is typically performed at –46°C (–50°F) to confirm suitability for low-temperature service.

Blind Flange Features

ASTM A350 LF2 blind flanges are solid flanges without a bore, designed to:

• Provide positive isolation of piping systems

• Withstand internal pressure at low temperatures

• Allow future system expansion or maintenance

They are commonly specified where system safety, reliability, and toughness are critical.

Dimensions & Pressure Classes

• Standard: ASME B16.5

• Pressure Classes:

  • Class 150

  • Class 300

  • Class 600

  • Class 900

  • Class 1500

  • Class 2500

• Size Range: 1/2″ – 24″

• Facing Types: RF, RTJ

• Manufacturing Process: Forged, Normalized

Inspection & Testing

ASTM A350 LF2 blind flanges are supplied with comprehensive inspection and testing, including:

• Chemical composition analysis

• Mechanical property testing

• Charpy V-notch impact testing

• Heat treatment verification

• Dimensional inspection

• Visual examination

• PMI (if required)

• Certification: EN 10204 3.1

Applications

• LNG and cryogenic piping systems

• Oil & gas transmission pipelines

• Petrochemical and refinery facilities

• Low-temperature pressure vessels

• Arctic and cold-region projects

ASTM A350 Grade LF2 is a general forged Carbon steel usually supplied in the Normalised, Normalised and Tempered or Quench and Tempered condition.It is typified by having moderate strength and impact toughness and is used extensively for the manufacture of flanges and forged fittings,

 Heat treatment requirement:

LF2 grade usually supplied in the Normalised, Normalised and Tempered or Quench and Tempered condition.

Hardness requirement 

Hardness HB <197HB this meets the requirements for carbon steel forgings in NACE MR0175/ISO 15156-2.

Flange Certification

In addition to the requirements of Specification A961/A961M, test reports shall be furnished to the purchaser or hisrepresentative. Test reports shall provide the following where applicable:

1 Type heat treatment, Section 5,

2 Chemical analysis results, Section 6 (Table 1), re￾ported results shall be to the same number of significant figures

as the limits specified in Table 1 for that element,

3 Product analysis results, 6.2 (Table 1),

4 Tensile property results, Section 7 (Table 2) report

the yield strength and ultimate strength, in ksi [MPa], elongation and reduction in area, in percent,

5 Impact test results, 7.2 (Table 3, Table 4, Table 5, and Table 6),

6 Hardness results, 7.3.1, and

7 Any supplementary testing required by the purchase order.

Related Products:

• ASTM A350 LF2 Weld Neck Flanges

• ASTM A350 LF2 Slip On Flanges

• ASTM A350 LF2 Socket Weld Flanges

• ASTM A350 LF2 Threaded Flanges

• ASTM A350 LF2 Forged Fittings