What is Flange?

What is Flange?

A flange, also known as a flange hub or projection, is a component used to connect shafts to each other or to join pipe ends. It is also employed at the inlets/outlets of equipment for connections, such as reducer flanges. A flange joint refers to a detachable sealing structure composed of flanges, gaskets, and bolts. Pipe flanges are specifically designed for pipeline installations, while equipment flanges are used for machinery connections. Flanges feature bolt holes to secure two mating flanges together with gaskets for sealing.

Flanges are categorized into threaded (screw-threaded), welded, and clamp types. They are always used in pairs: threaded flanges are suitable for low-pressure pipelines (≤4 kg/cm²), while welded flanges are required for higher pressures. A gasket is placed between the two flanges and tightened with bolts. The thickness of flanges and the specifications of bolts vary according to pressure ratings. Components like pumps and valves also incorporate flange structures for pipeline connections, though only smaller devices (e.g., valves) are classified as "flange-type parts."

Types of Flanges

A flange assembly typically consists of upper/lower flange plates, a gasket, and multiple bolts/nuts. Flanges can be classified by connection methods, including:

Integral Flange

Commonly used in high-pressure systems, this flange is integrally cast with a long neck. Materials include carbon steel and stainless steel.

Flat welded flanges

Also known as a socket-weld flange, it is welded to pipes or vessels. Advantages include ease of installation and cost-effectiveness, making it ideal for low-pressure, low-vibration pipelines.

Butt-weld Flange (Long-neck Flange)

Distinguished by a tapered neck that gradually matches the pipe’s wall thickness and diameter, enhancing strength. Suitable for extreme conditions like high/low temperatures and pressures.

Lapped Flange

Used with non-ferrous metals or stainless steel pipes. The rotating flange simplifies bolt-hole alignment, making it suitable for large-diameter or frequently dismantled connections. However, it is limited to low-pressure applications.

Threaded Flange

Features internal threads to mate with externally threaded pipes. Non-welded installation allows easy disassembly but is unsuitable for extreme temperatures due to thermal expansion/contraction risks.

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Features of Flanges

Structural Characteristics

Composed of flange plates, gaskets, and bolts, used in pairs for sealed connections via bolt tightening.

Thickness and bolt specifications vary by pressure grade to ensure connection strength.

Diverse sealing surface types (e.g., flat, male-female, tongue-and-groove) adapt to different media and operating conditions.

Material and Performance

Materials include carbon steel, stainless steel, alloy steel, non-ferrous metals, and plastics, suitable for corrosive, high-temperature, or high-pressure environments.

Forged flanges offer superior strength and temperature/pressure resistance, while cast flanges are cost-effective but slightly weaker mechanically.

Installation and Maintenance

Removable design facilitates repairs and replacements. Threaded flanges eliminate welding needs, and loose flanges rotate for easy bolt-hole alignment, ideal for large-diameter pipes or frequent disassembly.

Applications of Flanges

Industrial Sector

Pipeline Connections: Widely used in chemical, petroleum, power, and shipbuilding industries for modular pipeline systems.

Equipment Interfaces: Joins pumps, valves, and pressure vessels (e.g., Header - to-shell connections) to ensure sealing and structural stability.

Extreme Environments: Butt-weld and loose flanges meet demands in high/low temperatures, pressures, or corrosive media.

Civil and Construction Uses

HVAC and fire protection systems use flanges (e.g., grooved flanges) for quick, reliable installations.

Flange Pricing

Flange prices are significantly influenced by material, specifications, pressure ratings, and manufacturing processes. Below is a reference range for common types:

Slip-on Flanges

Carbon steel: DN15 ≈ ¥4-5; DN50 ≈ ¥12-18; DN100 ≈ ¥28-35 (10-16kg pressure).

Stainless steel: DN15 ≈ ¥12-20; DN50 ≈ ¥30-50; DN100 ≈ ¥80-100.

Forged Flanges

High-pressure carbon steel: DN15 ≈ ¥25; DN200 ≈ ¥500-1000.

Special Types

Grooved flanges: DN200 ≈ ¥46; adapter flanges ≈ ¥18-26.

Lined (fluoroplastic) flanges: DN50 ≈ ¥230-300.

Prices may fluctuate due to market demand and raw material costs. Custom or large-diameter flanges are generally more expensive.

Selection should consider pressure, temperature, media characteristics, and installation convenience.

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Supplier of Flanges

At LTZC, we pride ourselves on being a top - notch flange supplier. With years of experience in the industry, we offer a comprehensive selection of high - quality flange products that meet the diverse requirements of various sectors. Our product portfolio includes threaded flanges, slip - on flanges, butt - weld flanges, loose flanges, and threaded flanges. No matter if your project demands carbon steel, stainless steel, alloy steel, or non - ferrous materials, we have got you covered.

We are well - known for our ability to provide flanges suitable for different pressure ratings and temperature conditions. From low - pressure slip - on flanges to high - strength forged flanges, and from grooved flanges designed for easy installation to lined flanges for corrosive environments, we have it all. Our team of experts is committed to providing customized solutions. Whether you need flanges for pipeline systems, equipment interfaces, or special projects in the chemical, petroleum, power, or construction industries, we can deliver.

As a reliable flange supplier, we strictly follow international standards and implement rigorous quality control processes. This ensures that every flange we produce is durable, leak - proof, and can perform well in harsh conditions. We also offer flexible services, including rapid prototyping for urgent orders, competitive pricing, and worldwide shipping.

When you choose LTZC, you are not just getting a supplier; you are getting a long - term partner. We are dedicated to meeting your specific needs and exceeding your expectations. Get in touch with us today to discover how our premium flanges can enhance the efficiency and safety of your projects.