Flensa leher las adalah salah satu jenis flensa yang paling banyak digunakan dalam sistem perpipaan industri. Diakui karena daya tahannya, kekuatan, dan kemampuan untuk menangani kondisi tekanan tinggi dan suhu tinggi, they are a top choice in industries like oil and gas, petrokimia, pembangkit listrik, dan pembuatan kapal.

This complete guide will cover everything you need to know about weld neck flanges, including their types, ukuran, bahan, keuntungan, dan aplikasi umum.

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Apa itu Flensa Leher Las?

A weld neck flange (flensa WN) is a type of flange with a long tapered hub and a smooth transition to the wall thickness of a pipe or fitting. It is designed to be butt-welded to the pipe, menciptakan yang kuat, leak-proof connection that can withstand high stress. The tapered hub also reduces stress concentration at the base of the flange.

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Fitur Utama Flensa Leher Las

• Butt-Weld Connection: Ensures strength and minimizes stress at the joint.

• Hub Meruncing: Provides reinforcement and smooth stress distribution.

• Bore Matching: The flange bore matches the pipe’s inner diameter for smooth fluid flow.

• High Integrity: Ideal for critical service conditions.

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Jenis Flensa Leher Las

1. Standard Weld Neck Flanges

• Commonly used in pipelines where pressure and temperature are high.

• Suitable for a wide range of applications.

2. Flensa Leher Las Panjang

• Feature an extended hub, often used in equipment like nozzles or vessels.

• Provide additional reinforcement.

3. Reducing Weld Neck Flanges

• Used to connect pipes of different diameters.

• Maintain system integrity while accommodating size changes.

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Weld Neck Flange Dimensions

Weld neck flanges are manufactured according to international standards such as ASME B16.5, ASME B16.47, DIN, EN, dan lainnya. Dimensions vary based on nominal pipe size (NPC), kelas tekanan, dan standar.

Key Dimensional Factors:

• Diameter Luar (DARI): Overall flange size.

• Bore Diameter: Matches the pipe ID.

• Hub Length: Length of the tapered section.

• Ketebalan: Affects pressure rating.

• Diameter Lingkaran Baut: Distance between bolt holes.

Common Pressure Ratings:

• Kelas 150

• Kelas 300

• Kelas 600

• Kelas 900

• Kelas 1500

• Kelas 2500

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Materials Used for Weld Neck Flanges

The choice of material depends on operating temperature, tekanan, dan tipe fluida.

Bahan Umum:

• Baja Karbon: ASTM A105, A350 LF2 (low-temp service)

• Baja Tahan Karat: ASTM A182 F304, F316

• Baja Paduan: ASTM A182 F11, F22

• Rangkap & Super Dupleks: UNS S31803, S32750

• Paduan Nikel: tidak konel, Monel, Hastelloy

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Proses Manufaktur

1. Pemilihan Bahan – Choose appropriate grade for service conditions.

2. Penempaan – The flange is shaped through forging for strength.

3. permesinan – Precision machining ensures dimensional accuracy.

4. Perlakuan Panas – Relieves stress and enhances mechanical properties.

5. Inspeksi & Pengujian – Includes dimensional checks, NDT, and pressure testing.

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Keuntungan Flensa Leher Las

• Kekuatan Tinggi: Butt-welded connection provides excellent structural integrity.

• Leak Resistance: Cocok untuk aplikasi bertekanan tinggi dan suhu tinggi.

• Aliran Halus: Bore matching minimizes turbulence.

• Daya tahan: Long service life under extreme conditions.

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Disadvantages

• Biaya Lebih Tinggi: More expensive than slip-on or threaded flanges.

• Installation Time: Requires welding, which can be time-consuming.

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Applications of Weld Neck Flanges

1. Minyak & Pipa Gas

Used in upstream, tengah sungai, and downstream applications due to their strength and reliability.

2. Pabrik Petrokimia

Ideal for transporting chemicals under high pressure and temperature.

3. Pembangkit Listrik

Used in steam, air pendingin, dan sistem bahan bakar.

4. Pembuatan kapal & Di lepas pantai

Withstand harsh marine environments and high-pressure systems.

5. High-Temperature Services

Maintain integrity under extreme heat in refineries and chemical plants.

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Inspection and Quality Control

Weld neck flanges must undergo rigorous testing before being approved for service:

• Inspeksi Visual: Checks for surface defects.

• Dimensional Verification: Ensures compliance with standards.

• Pengujian Non-Destruktif (NDT): Ultrasonic or radiographic testing for internal flaws.

• Pengujian Hidrostatis: Confirms pressure containment.

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Pedoman Instalasi

1. Penyelarasan: Ensure the pipe and flange bores align perfectly.

2. Pengelasan: Perform butt-welding using approved procedures.

3. Bolt Tightening: Use a cross-pattern method for even gasket compression.

4. Pemilihan Gasket: Match gasket type to service conditions.

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Weld Neck vs Other Flange Types