A Step-by-Step Guide for Engineers and Industrial Buyers

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, 安全性を確保する機械的コネクタとして機能します。, 漏れ防止, パイプ間の修理可能なジョイント, バルブ, パンプス, と設備. But with so many standards, 圧力定格, and sizes available, one key question arises — how to know the correct flange size

この記事では, ササフランジ explains how to identify the correct flange size for your application, including the key dimensions, measurement techniques, and reference standards. Whether you are sourcing parts for a new project or replacing an existing flange, this guide will help you avoid errors and ensure proper system performance.

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Why Choosing the Right Flange Size Matters

Selecting the wrong flange size can lead to misalignment, pressure failures, increased leakage risk, and costly rework. Getting the flange size right is critical to

• Ensuring system compatibility

• Meeting pressure and temperature requirements

• Achieving proper sealing with gaskets

• Simplifying installation and maintenance

• Avoiding costly downtime or safety issues

で ササフランジ, we support customers in choosing flange dimensions that comply with global standards such as ASME, EN, DIN, JISと.

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What Are the Key Flange Size Parameters

To identify or confirm the correct flange size, you need to understand and measure several key dimensions

1. 呼びパイプサイズ (NPS) またはDN

This refers to the size of the pipe the flange is intended to connect. 北米では, NPS (in inches) 使用されています. In Europe and other regions, DN (diameter nominal in mm) 当てはまる.

2. 圧力定格 (Class or PN)

Defines the maximum pressure a flange can withstand. Common ASME classes are 150, 300, 600, 900, そして 1500. For EN/DIN standards, pressure ratings are shown as PN10, PN16, PN40, 等.

3. 外径 (の)

The total diameter of the flange face, important for proper alignment with mating components.

4. ボルト円直径 (BCD or PCD)

The diameter of the circle passing through the center of each bolt hole.

5. Number and Size of Bolt Holes

Bolt quantity and diameter must match exactly to ensure tight, leak-free assembly.

6. フランジの厚さ

Measured from face to back, thickness affects strength and gasket compression.

7. Bore or Inner Diameter

Should match the outside diameter of the connecting pipe to maintain flow continuity.

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How to Determine the Correct Flange Size

Follow these steps to ensure you choose the correct flange size

ステップ 1: Identify the Pipe Size

Check the nominal pipe size (NPS または DN). If you’re replacing an existing flange, measure the inside diameter and wall thickness of the pipe it connects to.

ステップ 2: Confirm the Pressure Rating

Refer to the piping system design or operating conditions. If the system operates under high pressure or temperature, a higher class (例えば, クラス 300 or PN40) is required.

ステップ 3: Measure the Flange Dimensions

Use calipers or a measuring tape to determine

• 外径

• ボルト円直径

• ボルト穴の数と大きさ

• Bore and thickness

Compare your measurements with a standard flange dimension chart (のような ASME B16.5 またはEN 1092-1) to verify the size.

ステップ 4: Check the Flange Type and Face

Is it a weld neck, スリッポン, 盲目, ソケット溶接, or threaded flange Is it raised face, 平らな面, or ring-type joint This affects both installation and gasket compatibility.

ステップ 5: Confirm Standards and Material

Ensure the flange material (例えば, ステンレス鋼, 炭素鋼, 合金鋼) and manufacturing standard match your system requirements.

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Flange Size Chart Example (ASME B16.5, クラス 150, NPS 4)