Detailed Explanation of Integral Flanges: Classification, Characteristics, Applications, and Standards Guide
Content
- Preface
- What is an integral flange?
- Classification of integral flanges
- Structural characteristics of integral flanges
- Applications of integral flanges
- Standard guidelines for integral flanges
- Advantages and disadvantages of integral flanges
- Installation and inspection of integral flanges
- How to choose an integral flange
- Integral flanges vs plate flanges
- Summary
Preface
Integral flanges, as a crucial component of pipeline connections, are characterized by high strength, stability, and ease of installation.
By understanding the different types of integral flanges and their characteristics, we can better select the appropriate flange type to meet engineering needs.
This article provides a detailed introduction to integral flanges, hoping to help you choose the right flange.
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What is an integral flange?
An integral flange is a single flange plate, typically cast or forged directly into the equipment or pipeline.
Unlike other types of flanges that consist of multiple parts, it is a single, integral structure. This design gives integral flanges greater strength and stability in pipeline connections.
Classification of integral flanges
Depending on their application and connection method, integral flanges can be divided into several types. Among them, the most common include slip-on flanges, butt-weld flanges, and threaded flanges.
Slip-on welding flanges
Flat-face flanges are made by inserting the pipe into the flange bore to the appropriate position and then welding it.
Their advantages are that they are easier to align during welding and assembly, and they are inexpensive, so they have been widely used.
Butt welding flanges
Welding flanges, also known as high-neck flanges, differ from other flanges in that they have a long and sloping high neck from the weld joint between the flange and the pipe to the flange plate.
The wall thickness of this high neck gradually transitions to the pipe wall thickness along the height direction, improving the discontinuity of stress and thus increasing the flange strength.
Threaded flanges
A threaded flange is a non-welded flange where the inner bore of the flange is machined with pipe threads to connect with a threaded pipe.
Compared to welded flanges, it is easier to install and maintain, and can be used on pipelines where welding is not permitted on site.
Structural characteristics of integral flanges
The core features of integral flanges are: High strength: Because they are integrally molded with the body material, stress concentration at bolted connections is avoided, resulting in stronger pressure resistance.
For example, in the ASME B16.5 standard, Class 150 integral flanges can be designed for pressures up to 1.9 MPa.
Good sealing performance: The flange face seamlessly connects to the equipment, reducing the risk of leakage and making it suitable for pipelines carrying flammable and toxic media.
Applications of integral flanges
Pipeline Connections
Used for transporting various liquids, gases, and solids, such as in the fields of oil, natural gas, chemicals, food, pharmaceuticals, and wastewater treatment.
Equipment Connections
Connect various equipment and machinery, such as engines, pumps, compressors, heat exchangers, and air conditioning equipment.
Supports
Serving as supporting components for pipelines or equipment, improving their stability and reducing vibration and deformation caused by stress.
Sealing
Utilizing the principle of surface sealing, ensuring that the connection does not leak air, water, or oil, thereby guaranteeing the safe and reliable operation of the fluid transport system.
Standard guidelines for integral flanges
Advantages and disadvantages of integral flanges
Advantages:
- Tight Connection: Because the integral flange is a product integrating the pipe fitting and flange, the connection is tight and leaks are less likely.
- Simple Structure: The integral flange has a relatively simple structure and is easy to install.
- Good Sealing Performance: The integral flange has good sealing performance and can meet the requirements of use under special conditions such as high pressure, high temperature, and corrosion.
- Long Service Life: Due to its tight connection, good sealing performance, and simple structure, the integral flange has a long service life.
Disadvantages:
- Relatively High Price: The manufacturing process of integral flanges is more complex, resulting in a relatively high price.
- Limited Application Range: Integral flanges are typically used for connections under special conditions such as high temperature, high pressure, and corrosion.
Installation and inspection of integral flanges
Installation Specifications: Bolts must be tightened symmetrically, gradually increasing pressure to the rated torque in three stages.
The flange sealing surface must be free of scratches, and the gasket should be made of a material compatible with the medium.
Regular Inspection: Use ultrasonic or penetrant testing to check the flange neck weld for cracks.
For high-pressure systems, it is recommended to perform an airtightness test every 6 months, at a pressure of 1.5 times the working pressure.
How to choose an integral flange
Material Matching: The flange material must be selected based on the characteristics of the medium. For example:
- Corrosive media: 316L stainless steel or Hastelloy are preferred.
- High-temperature environments: The coefficient of thermal expansion of the material must be considered. For example, the upper limit of long-term operating temperature for carbon steel flanges is 425℃ (refer to ASME standards).
Standard Compliance: The flange must comply with industry standards (such as GB/T 9119, ASME B16.5) to ensure that the flange dimensions are compatible with the piping system.
Integral flanges vs plate flanges
| Feature | Integral Flange (Weld Neck) | Plate Flange |
| Hub Design | Tapered hub for stress transfer | Flat plate, no hub |
| Connection to Pipe | Butt weld (full penetration) | Fillet weld (inside & outside) |
| Bore Matching | Precise match to pipe ID | Requires manual alignment |
| Rigidity | High (monolithic construction) | Lower (flat plate geometry) |
| Parameter | Integral Flange | Plate Flange |
| Pressure Rating | Full ASME Class range (150 to 2500) | Typically limited to Class 150/300 |
| Fatigue Resistance | Excellent (reduces stress concentration) | Poor (high stress at weld junction) |
| Cost Factor | Higher (more material, complex machining) | Lower (simple manufacturing) |
| Typical Use | High-pressure, cyclic, severe service | Low-pressure, non-critical utility |
Summary
Through the article above, we have gained a detailed understanding of the characteristics, applications, and standards of integral flanges, and we believe you now have a deeper understanding of flange selection.
Metleader, as a professional flange manufacturing company, can provide customers with complete flange solutions.
If your project requires flanged pipe fittings, please feel free to contact us. Our engineers will provide free technical support!
