ウェルドネック フランジは、工業用配管システムで最も広く使用されているフランジ タイプの 1 つです. 耐久性が認められている, 強さ, 高圧および高温条件に対処する能力, they are a top choice in industries like oil and gas, 石油化学製品, 発電, そして造船.

This complete guide will cover everything you need to know about weld neck flanges, including their types, 寸法, 材料, 利点, and common applications.

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ウェルドネックフランジとは?

A weld neck flange (WNフランジ) 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, 強いものを生み出す, 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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ウェルドネックフランジの主な特徴

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

• テーパーハブ: 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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ウェルドネックフランジの種類

1. Standard Weld Neck Flanges

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

• Suitable for a wide range of applications.

2. ロングウェルドネックフランジ

• 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, その他. Dimensions vary based on nominal pipe size (NPS), 圧力クラス, and standard.

Key Dimensional Factors:

• 外径 (の): Overall flange size.

• Bore Diameter: Matches the pipe ID.

• Hub Length: Length of the tapered section.

• 厚さ: Affects pressure rating.

• ボルト円直径: Distance between bolt holes.

Common Pressure Ratings:

• クラス 150

• クラス 300

• クラス 600

• クラス 900

• クラス 1500

• クラス 2500

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Materials Used for Weld Neck Flanges

The choice of material depends on operating temperature, プレッシャー, そして液体タイプ.

Common Materials:

• 炭素鋼: ASTM A105, A350 LF2 (low-temp service)

• ステンレス鋼: ASTM A182 F304, F316

• 合金鋼: ASTM A182 F11, F22

• 二重 & スーパーデュプレックス: UNS S31803, S32750

• ニッケル合金: インコネル, モネル, ハステロイ

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製造工程

1. 材料の選択 – Choose appropriate grade for service conditions.

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

3. 機械加工 – Precision machining ensures dimensional accuracy.

4. 熱処理 – Relieves stress and enhances mechanical properties.

5. 検査 & テスト – Includes dimensional checks, NDT, and pressure testing.

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ウェルドネックフランジの利点

• 高強度: Butt-welded connection provides excellent structural integrity.

• 耐漏れ性: 高圧・高温用途に最適.

• Smooth Flow: Bore matching minimizes turbulence.

• 耐久性: Long service life under extreme conditions.

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Disadvantages

• Higher Cost: 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. 油 & ガスパイプライン

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

2. 石油化学プラント

Ideal for transporting chemicals under high pressure and temperature.

3. 発電

Used in steam, cooling water, and fuel systems.

4. 造船 & オフショア

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:

• 目視検査: Checks for surface defects.

• Dimensional Verification: Ensures compliance with standards.

• 非破壊検査 (NDT): Ultrasonic or radiographic testing for internal flaws.

• 静水圧試験: Confirms pressure containment.

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設置ガイドライン

1. 位置合わせ: Ensure the pipe and flange bores align perfectly.

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

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

4. ガスケットの選択: Match gasket type to service conditions.

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Weld Neck vs Other Flange Types