ASTM A350 LF2 Class 1 Weld Neck Flange

ASME B16.5 WNRF & RTJ Low Temperature Flanges

ASTM A350 LF2 Class 1 weld neck flanges are forged low-temperature carbon steel flanges designed for pressure piping systems operating in sub-zero environments.
Manufactured in accordance with ASME B16.5, these flanges are supplied with Weld Neck Raised Face (WNRF) and Ring Type Joint (RTJ) facings, providing excellent sealing performance under high pressure and low temperature conditions.

LF2 Class 1 weld neck flanges are widely specified in oil & gas, LNG, petrochemical, and low-temperature processing facilities, where impact toughness, structural integrity, and long-term reliability are critical.

What Is ASTM A350 LF2 Class 1?

ASTM A350 is a material specification covering forged carbon and low-alloy steel flanges and fittings intended for low-temperature service.
LF2 is the most commonly used grade, and Class 1 (CL1) refers to material supplied with mandatory Charpy V-notch impact testing and controlled heat treatment.

ASTM A350 LF2 CL1 flanges are typically supplied in the normalized or normalized and tempered condition to ensure consistent mechanical properties and excellent low-temperature toughness.

ASTM A350 LF2 is one of the most popular grade for the forgings,flanges,fittings specially used for low temperature  environment.

There are 2 grades in ASTM A350 LF2 material grade.ASTM A350 LF2  CL1 &ASTM A350 LF2  CL2.

Class 1 and Class 2 of ASTM A350/ ASME SA-350 grade LF2 have the same chemical composition and mechanical properties. Even the allowable stresses of Class 1 and Class 2 in ASME Codes are the same. 

The difference between Class 1 and Class 2 in accordance with ASME SA 350 for LF2 is Charpy impact requirements
for LF2 Cl.1 – the minimum Charpy impact is 15 ft-lbs   @-50 deg F
for LF2 Cl.2 – the minimum Charpy impact is 20 ft-lbs    @0 deg F

ASTM A350 Grade LF2 Class 1 is a steel grade for carbon and low alloy steel forgings, requiring notch toughness testing for piping components. This includes forged flanges, fittings, valves and similar forged and machined parts. This specification covers requirements such as chemical composition, mechanical properties and impact test for notch toughness.

We supply high quality of ASTM A350 Grade LF2 Class 1 Flanges according to ASME B16.5 ASME B16.47 EN 1092-1

Chemical Composition:

MECHANICAL CHARACTERISTICS (ASTM A350M-07)

A350 LF2 Cl1 Weld neck Flanges or welding neck flange is well recognised for its long-tapered hub, which provides mechanical strength (useful to resist ‘dishing’ and ‘bowing’). Welding neck flanges are high integrity flanges and are available in all sizes, all common face types (flat, raised, RTJ), and all classes

Weld Neck Flange Design (WNRF & RTJ)

Weld neck flanges feature a long tapered hub that is butt-welded to the pipe, providing:

• Smooth stress transition

• Excellent fatigue resistance

• High strength for pressure and cyclic service

Facing Types

• WNRF (Weld Neck Raised Face):
  Suitable for most low-temperature pressure piping systems

• RTJ (Ring Type Joint):
  Designed for high-pressure and critical service, commonly used in oil & gas and LNG projects

Dimensions & Pressure Classes

• Material Standard: ASTM A350 / ASME SA350

• Grade: LF2 Class 1

• Flange Standard: ASME B16.5.ASME B16.47

• Pressure Classes:

  • Class 150

  • Class 300

  • Class 600

  • Class 900

  • Class 1500

  • Class 2500

• Size Range: 1/2″ – 60″

• Manufacturing Process: Forged, Normalized

Inspection & Testing

ASTM A350 LF2 CL1 weld neck 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

How to order our ASTM A350 LF2 CL1  WNRF Flanges,ASTM A350 LF2 CL1  WNRTJ Flanges?

Product: ASTM A350 LF2 CL1 Weld Neck Flange  Raise face (WNRF)

Standard: ASME B16.5
Pressure Rating: Class 600
Size: 8 Inch (DN200)
Facing Type: Raised Face (RF)
Schedule: SCH 80
Quantity: 20 pieces
Testing: Impact Test at -46°C, Ultrasonic Test
Certification: EN 10204 Type 3.1
Delivery Condition: Normalized + Tempered

Product: ASTM A350 LF2 CL1 Weld Neck Flange Ring type Joint  (WNRTJ)

Standard: ASME B16.5
Pressure Rating: Class 1500
Size: 12 Inch (DN300)
Facing Type: Ring type Joint  (WNRTJ)
Schedule: SCH 80
Quantity: 50 pieces
Testing: Impact Test at -46°C, Ultrasonic Test
Certification: EN 10204 Type 3.1
Delivery Condition: Normalized + Tempered