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

Фланцы являются важными компонентами трубопроводных систем., действуют как механические соединители, которые обеспечивают безопасность, герметичный, и исправные соединения между трубами, клапаны, насосы, и оборудование. But with so many standards, номинальное давление, and sizes available, one key question arises — how to know the correct flange size

В этой статье, Сасафланж 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.

---

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

В Сасафланж, we support customers in choosing flange dimensions that comply with global standards such as ASME, EN, DIN, и ДЖИС.

---

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. Номинальный размер трубы (НПС) или DN

This refers to the size of the pipe the flange is intended to connect. В Северной Америке, НПС (in inches) используется. In Europe and other regions, DN (diameter nominal in mm) применяется.

2. Номинальное давление (Class or PN)

Defines the maximum pressure a flange can withstand. Common ASME classes are 150, 300, 600, 900, и 1500. For EN/DIN standards, pressure ratings are shown as PN10, PN16, Ру40, и т. д..

3. Внешний диаметр (ИЗ)

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

4. Диаметр окружности болта (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. Flange Thickness

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.

---

How to Determine the Correct Flange Size

Follow these steps to ensure you choose the correct flange size

Шаг 1: Identify the Pipe Size

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

Шаг 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 (например, Сорт 300 or PN40) is required.

Шаг 3: Measure the Flange Dimensions

Use calipers or a measuring tape to determine

• Внешний диаметр

• Диаметр окружности болта

• Number and size of bolt holes

• Bore and thickness

Compare your measurements with a standard flange dimension chart (такой как ASME B16.5 или RU 1092-1) to verify the size.

Шаг 4: Check the Flange Type and Face

Is it a weld neck, без шнуровки, слепой, раструбная сварка, or threaded flange Is it raised face, плоское лицо, or ring-type joint This affects both installation and gasket compatibility.

Шаг 5: Confirm Standards and Material

Ensure the flange material (например, нержавеющая сталь, углеродистая сталь, легированная сталь) and manufacturing standard match your system requirements.

---

Flange Size Chart Example (ASME B16.5, Сорт 150, НПС 4)