フランジは、配管システムに不可欠なコンポーネントです, enabling secure connections between pipes, バルブ, パンプス, およびその他の機器. Among the different international standards, ANSI flanges are widely used in industries such as oil and gas, 化学処理, 発電, 水処理, そして造船. ANSI stands for the American National Standards Institute, which establishes dimensional and pressure standards for flanges to ensure safety, 互換性, and interchangeability.

When selecting or designing systems with ANSI flanges, engineers and procurement professionals must take into account several key considerations. These factors determine not only the performance and safety of the system but also its long-term reliability and cost-effectiveness.

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What Are ANSI Flanges?

ANSI flanges are piping connection components designed and manufactured according to standards set by the American National Standards Institute. The most widely referenced specification is ANSI/ASME B16.5, which covers pipe flanges and flanged fittings ranging from ½ inch to 24 inches in nominal size and from Class 150 クラスへ 2500 in pressure ratings.

Common Types of ANSI Flanges:

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

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

• ソケット溶接フランジ – Used in small-diameter, 高圧配管

• ねじ付きフランジ – Requires no welding, suitable for low-pressure applications

• ブラインドフランジ – Used to seal off the end of a pipe or nozzle

• ラップジョイントフランジ – Paired with a stub end for easy alignment and dismantling

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ANSI フランジに関する重要な考慮事項

1. 材料の選択

The choice of material affects both performance and durability. ANSI flanges can be manufactured from:

• 炭素鋼 – 費用対効果が高い, 強い, but limited corrosion resistance

• ステンレス鋼 – Excellent corrosion resistance, widely used in chemical and marine environments

• 合金鋼 – Suitable for high-temperature and high-pressure conditions

• ニッケル合金 – Best for aggressive chemical processing applications

ヒント: Always match flange material with the piping material to avoid galvanic corrosion.

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2. 圧力定格

ANSI flanges are classified into different 圧力クラス, 含む 150, 300, 600, 900, 1500, そして 2500. These ratings indicate the maximum pressure the flange can withstand at a given temperature.

• クラス 150 – Suitable for low-pressure water pipelines

• クラス 600 – Common in oil and gas pipelines

• クラス 2500 – Used in very high-pressure environments such as refineries and power plants

ヒント: Always consider both 圧力と温度 simultaneously, as pressure capacity decreases at higher temperatures.

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3. 直面しているタイプ

The facing of a flange ensures a proper seal between mating surfaces. ANSI flanges have several facing options:

• 盛り上がった顔 (RF): 最も一般的な, provides good sealing performance

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

• リング型ジョイント (RTJ): Ideal for high-pressure and high-temperature environments

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

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4. ガスケットの互換性

The gasket is critical for leak prevention. Selecting the wrong gasket can lead to system failure.

• 非金属ガスケット (ゴム, PTFE) – For low-pressure systems

• メタルガスケット (螺旋状の傷, ring joint) – For high-pressure, 高温用途

ヒント: Ensure the gasket material is chemically compatible with the process fluid.

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5. Bolt Selection and Torque

Bolts hold flanges together, and correct torque application is crucial to prevent leakage.

• Use high-quality, 耐食ボルト.

• Follow torque tightening sequences (typically crisscross patterns).

• Avoid over-tightening, which may damage gaskets.

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6. 規格への準拠

ANSI flanges must comply with:

• ASME B16.5 – Pipe flanges and fittings up to 24 インチ

• ASME B16.47 – 大径スチールフランジ

• ASME B31.3 – Process piping design codes

Ensuring compliance guarantees interchangeability, 安全性, そして品質保証 across projects.

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7. 設置とメンテナンス

Proper installation ensures long-term performance.

• Inspect flanges for cracks, 反る, or corrosion before use

• Ensure correct alignment of flanges to avoid undue stress

• Use appropriate lubricants for bolts

• Regularly inspect joints during maintenance cycles

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Advantages of ANSI Flanges

1. 世界標準化 – Ensures compatibility across industries worldwide

2. Wide Availability – Standardized sizes and materials are readily available

3. 柔軟性 – Multiple types for various applications

4. 耐久性 – Designed to withstand high pressure and temperature conditions

5. 安全性 – Compliance with ANSI standards ensures reliable performance

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Applications of ANSI Flanges

石油とガス

• Pipelines, オフショアプラットフォーム, 製油所

• High-pressure and high-temperature connections

化学処理

• リアクター, distillation units, 貯蔵タンク

• Resistant stainless steel and alloy flanges are preferred

発電

• 蒸気ライン, cooling water systems, nuclear plants

• High-strength flanges in Class 600–2500

海洋および造船

• バラストシステム, 淡水化プラント, cooling systems

• Corrosion-resistant stainless steel flanges

Water Treatment and Infrastructure

• Pipelines for water distribution and wastewater management

• Large diameter flanges ensure efficient flow

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ANSI Flanges vs. Other Standards