Pipe flanges are vital components in piping systems, パイプ間のコネクタとして機能します, バルブ, パンプス, およびその他の機器. 彼らは提供します 強さ, flexibility, そしてメンテナンスの容易さ in industries such as oil and gas, 化学処理, 発電, 水処理, そして造船. Choosing the right flange is essential to ensure 安全性, 信頼性, そして費用対効果 of the system.

This article explains what to look for in pipe flanges, focusing on key considerations such as materials, 圧力定格, 対面タイプ, 標準, とアプリケーション. By understanding these aspects, engineers and procurement professionals can make informed decisions when selecting flanges.

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What Are Pipe Flanges?

A pipe flange is a forged or cast ring that allows the connection of pipes, 継手, バルブ, and other components. Flanges are joined by bolting and sealing with a gasket, creating a leak-proof joint that can be dismantled when necessary.

Common Types of Pipe Flanges:

• 溶接ネックフランジ – Strong and suitable for high-pressure systems

• スリップオンフランジ – 取り付けが簡単, used in low-to-medium pressure pipelines

• ソケット溶接フランジ – Ideal for small-diameter, 高圧システム

• ねじ付きフランジ – Used where welding is not possible

• ラップジョイントフランジ – Allows easy alignment, often used with stub ends

• ブラインドフランジ – Used to close or seal off a pipeline

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Key Factors to Look For in Pipe Flanges

1. 材料の選択

Material choice directly affects performance, 耐食性, そして耐久性.

• 炭素鋼 – Economical, 高強度, used in general industry

• ステンレス鋼 – Excellent resistance to corrosion and oxidation

• 合金鋼 – Withstands high temperatures and pressures

• ニッケル合金 – Superior resistance to aggressive chemicals

• 二相および超二相ステンレス鋼 – Outstanding strength and chloride corrosion resistance

ヒント: Always ensure flange material matches the pipe material to avoid galvanic corrosion.

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2. 圧力定格

Flanges are classified into 圧力クラス, indicating the maximum pressure they can withstand at a specific temperature.

• クラス: 150, 300, 600, 900, 1500, そして 2500 (per ANSI/ASME B16.5)

• Higher class = higher pressure and temperature capability

例:

• クラス 150: Used for low-pressure water pipelines

• クラス 600 以上: Required in refineries and power plants

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3. Flange Facing Types

The flange facing ensures proper gasket seating and leak-proof connections.

• 盛り上がった顔 (RF): 最も一般的な, good for general-purpose sealing

• 平面 (FF): Used in low-pressure systems or with cast iron equipment

• リング型ジョイント (RTJ): 高圧向けに設計, high-temperature conditions

• 男性と女性 / タング・アンド・グルーブ: Prevents gasket displacement and ensures precise alignment

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4. ガスケットの互換性

The gasket material must match the flange facing and operating environment.

• Soft Gaskets (ゴム, PTFE): Suitable for low-pressure applications

• うず巻形ガスケット: Widely used in high-pressure and high-temperature systems

• Ring Joint Gaskets: Specifically for RTJ facings in extreme conditions

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5. 規格とコンプライアンス

Pipe flanges must comply with international standards to ensure safety and interchangeability.

• ASME/ANSI B16.5: Pipe flanges up to 24 インチ

• ASME B16.47: Large-diameter flanges

• DIN/EN Standards: ヨーロッパで広く使われている

• JIS規格: Common in Japan and Asia

ヒント: Always confirm client or project requirements before procurement.

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6. Dimensions and Tolerances

• チェック outer diameter (の), inner diameter (ID), ボルト円径 (BCD), と厚さ.

• Ensure tolerances meet project design codes to prevent misalignment.

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7. Bolt and Torque Requirements

Bolts must be selected based on:

• 材料: Corrosion resistance and strength

• Torque Application: Correct torque prevents both under-tightening (漏れ) and over-tightening (gasket damage).

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8. 耐食性

Pipelines exposed to seawater, 酸, or chemicals require flanges with high corrosion resistance.

• Stainless steel and duplex grades are preferred in marine and chemical plants.

• Coatings and linings can be used for carbon steel flanges in corrosive service.

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9. 設置とメンテナンス

• Inspect flanges before installation for cracks or warping

• Ensure proper alignment during installation

• Use torque sequences for bolts to ensure even pressure distribution

• Schedule regular maintenance checks to prevent leakage and downtime

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Applications of Pipe Flanges

1. 石油およびガス産業

   • Pipelines, 製油所, オフショアプラットフォーム

   • High-pressure weld neck and RTJ flanges

2. 化学および石油化学

   • リアクター, 貯蔵タンク, chemical pipelines

   • Stainless steel and alloy flanges for corrosion resistance

3. 発電

   • ボイラー, 蒸気ライン, nuclear plants

   • 高圧, high-temperature flanges

4. 海洋工学

   • バラストシステム, 淡水化プラント

   • Duplex stainless steel flanges

5. 水処理

   • Distribution pipelines, wastewater systems

   • Large-diameter slip-on and lap joint flanges

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Pipe Flanges vs. Other Connection Methods