Long Weld Neck Flange – Engineered Strength for Demanding Applications

Long Weld Neck Flange

Engineered Strength for Pressure-Critical Applications


🔩 Structural Features

  • One-piece forged flange with an extended tapered neck

  • Designed to replace pipe nipples or weld-on nozzles

  • Tapered neck provides reinforcement and ensures smooth flow transition

  • Commonly used in:

    • Pressure vessels

    • Heat exchangers

    • Storage tanks

  • Available flange face types:

    • RF (Raised Face)

    • RTJ (Ring-Type Joint)

    • FF (Flat Face)


🔧 Welding Method

  • Butt-welded at the base of the neck

  • Forms a continuous, integral structure with vessel or piping

  • Ensures high mechanical strength and stress resistance

  • Requires high-quality welding — often with:

    • Radiographic (RT) or

    • Ultrasonic (UT) non-destructive testing


🛠️ Applications

Ideal for critical industrial systems such as:

  • 🛢 Pressure vessels

  • 🏗 Column towers

  • 🔥 Heat exchangers

  • 🧊 Cryogenic systems

  • 🧪 Chemical processing plants

  • ⚡ Power generation equipment

  • 🔩 Custom fabrications requiring nozzle reinforcement


📏 Size Standards

  • Range: 1/2” to 120” (DN15–DN3000)

  • Reference Standards:

    • ASME B16.5 (2”–24”)

    • ASME B16.47 (Above 24”)

    • MSS-SP-44 (Large-diameter applications)


⚙️ Pressure Ratings

  • Class: 150#, 300#, 600#, 900#, 1500#, 2500#

  • Custom designs available for pressures exceeding standard ratings


🧪 Available Materials

  • Carbon Steel

  • Stainless Steel

  • Alloy Steel

  • Duplex Stainless Steel

  • Nickel Alloys


Recommendation

Long Weld Neck Flanges are the optimal solution where:

  • High strength and structural continuity are required

  • Reinforced nozzles or extended necks are necessary

  • Applications demand reliable performance under extreme conditions (pressure, temperature, stress)

NFI STEEL

Excellent manufacturer of flanges, butt welded pipe fittings, forged pipe fittings and pipe prefabrication in China.

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