What Is a Flange: Essential Guide for Piping Systems

May 21, 2024

Flanges are essential components in various industrial applications, serving to connect pipes, valves, pumps, and other equipment to form an integrated piping system. They not only aid in creating a sealable joint but also provide structural support and facilitate assembly and maintenance. Understanding the different types of flanges, their applications, and standards is crucial for ensuring the reliability and efficiency of any piping system.

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Definition and Purpose

A flange is a protruded ridge, lip, or rim, either external or internal. Its primary functions include increasing strength, facilitating easy attachment, and stabilizing or guiding movements of machines or their parts. In piping systems, flanges are critical for ensuring proper alignment, reducing stress, and simplifying installation and maintenance.

Applications in Piping and Plumbing

Piping Systems

Flanges allow easy access for maintenance, inspection, and modification. They enable the connection or disconnection of pipes and equipment without the need for welding, thereby simplifying installation and reducing downtime. Flanges also ensure proper alignment of pipes, minimizing stress and enhancing system performance.

Types of Flanges in Plumbing

Several types of flanges cater to specific purposes in plumbing systems, such as ensuring even water flow to showers or mounting toilets. Examples include Surrey, York, Sussex, Essex, and Warix flanges, as well as closet flanges for toilets.

"CAFE TANK CAPS / FLANGE" by REDMAXSPEEDSHOP.COM is licensed under CC BY-SA 2.0. To view a copy of this license, visit https://creativecommons.org/licenses/by-sa/2.0/.

Pipe Flanges

General Usage

Pipe flanges are used to connect pipes, valves, fittings, strainers, and pressure vessels. They are typically used with bolts and gaskets for sealing and require special protective measures in industries handling flammable, volatile, toxic, or corrosive substances.

Standards and Specifications

Various global standards govern the design and usage of flanges, including ASA/ASME (USA), PN/DIN (European), BS10 (British/Australian), and JIS/KS (Japanese/Korean). ASME B16.5 covers flanges up to 24 inches size, while B16.47 covers up to 60 inches. Pressure classes (e.g., Class 150, 300) define different pressure and temperature ratings depending on the material.

Flange Designs and Types


Common flange designs include weld neck, slip-on, lap joint, socket weld, threaded, and blind flanges. Each design has specific applications and advantages.


Different types of flanges serve various purposes:

  • Weld Neck: Provides reinforcement for high-pressure, high-temperature applications.
  • Slip-On: Slips over the pipe, used in low-pressure, non-critical applications.
  • Socket Weld: Fits the pipe end into a recessed area, suitable for small-bore systems.
  • Blind: Closes the end of a piping system, used for pressure testing or sealing.

Material Standards

ASME Standards

Common materials for flanges as per ASME standards include SA-105 (Carbon Steel Forgings), SA-266 (Carbon Steel for Pressure Vessels), and SA-182 (Forged Alloy-Steel). High tensile strength applications often utilize bolting materials like ASTM A193 B7 STUD and ASTM A193 B16.

European and Sanitary Applications

European Standards

EN 1092-1 standard covers stainless or steel flanges, including weld neck, blind, threaded, flat, and lapped forms, ensuring adherence to strict European specifications.

Hygienic Flanges

DIN 11853-2 flanges are used in food, beverage, and pharmaceutical industries, designed to limit dead space and maintain high hygienic standards.

Compact and Specialized Flanges

Compact Flanges

These flanges offer higher performance with a more sophisticated design, suitable for subsea oil and gas, cryogenics, high-temperature, and nuclear applications.

Train Wheels

Flanges on train wheels keep them on the rails, ensuring stability and safety.

Vacuum Flanges

Crucial in high-vacuum systems, vacuum flanges ensure the integrity of the vacuum environment.

Microwave and Ski Boots

Flanges are also used in telecommunications for microwave applications and in ski bindings to clip ski boots securely.

Understanding the various designs, applications, and standards of flanges is vital for selecting the right type for specific needs. Flanges play a critical role in maintaining stability, ensuring safety, and facilitating the efficient operation of piping systems across various industrial sectors. For any inquiries or assistance in selecting the appropriate flanges and piping components, technical sales experts are readily available for support.

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