Flange

As a critical component in the industrial sector, flanges offer advantages that extend far beyond their basic function of connecting pipes and equipment. First, flanges are highly versatile and interchangeable: whether used in piping systems of varying materials and specifications or in complex industrial machinery, their standardized design enables precise alignment, significantly streamlining installation and maintenance. Second, flanges provide excellent sealing performance; by selecting appropriate gaskets and tightening methods, they effectively prevent medium leakage, ensuring safe and stable system operation—particularly vital in industrial environments handling high-pressure, high-temperature, or corrosive media. Furthermore, flanges exhibit outstanding pressure‑ and temperature‑resistance, withstanding extreme operating conditions while maintaining structural integrity and prolonging equipment life. In addition, advances in manufacturing processes—from traditional casting and forging to modern precision machining—have enhanced both the accuracy and surface finish of flanges, reducing weight while increasing strength, thereby expanding their application scope and improving cost‑effectiveness. In summary, with these distinctive attributes, flanges play an indispensable role in industry and serve as a key foundation for advancing industrial automation and intelligence.
Flange connection process :

Flanged connections do not rely solely on the flanges themselves; rather, they constitute a combined sealing assembly comprising a pair of flanges, a gasket, and several bolts and nuts.

1.  Installation steps: Secure a flange to each end of the pipe, place a sealing gasket between them, and then fasten the two flanges together using bolts that pass through the flange bolt holes.

2.  Sealing principle: The bolt preload compresses the gasket, inducing plastic deformation that fills the irregularities on the flange sealing surfaces, thereby achieving leak prevention.

3.  Connection characteristics: This is a detachable joint; compared with direct welding, flanged connections facilitate subsequent equipment maintenance, replacement, and disassembly.

What are the common types of flanges?

Flanges are classified in various ways according to their connection method, structural design, and industry standards. The following are some of the most common types:

1.  By connection type:

   -  Welding flanges include slip-on flanges—simple in structure and low-cost, suitable for low-pressure applications—and butt-welded flanges—high-strength and capable of withstanding high pressure, ideal for high-temperature, high-pressure service.

   -  Threaded flanges: They are connected to pipelines by engaging the internal pipe threads, eliminating the need for welding. They are suitable for applications where hot work is prohibited, but their pressure‑bearing capacity is relatively limited.

   -  Slip-on flange: The flange and the pipe are not rigidly fixed; they can rotate freely, facilitating alignment during installation. It is commonly used in large-diameter pipelines.

2.  By industry standard: Chemicals ( HG ), petrochemical ( SH ), mechanical ( JB ) and national standards ( GB ) All such systems have different classifications.

3.  Other types include socket-weld flanges (used in small-diameter, high-pressure pipelines) and blind flanges (used to seal pipeline ends or provide a prepared interface).

How to Select and Use Flanges:

When selecting a flange, it is necessary to comprehensively consider factors such as pressure, temperature, the process medium, and the pipe material.

1.  Pressure rating: The typical pressure tolerance range is 0.6 MPa To 10.0MPa For high-pressure systems, butt-welded flanges or forged flanges are preferred.

2.  Material selection: Common materials include carbon steel, stainless steel, cast iron, and plastics (such as ...). PVC 、 PPR ) and so on; in highly corrosive environments, special alloys such as Hastelloy may be used.

3.  Standard system: Internationally, it is mainly divided into the European system (with Germany as its core)… DIN As a representative, adopt PN Nominal pressure marking) and the American system (in the United States ANSI As a representative, adopt Class Nominal pressure marking), China’s national standard GB It is compatible with both.

4.  Installation key points: The flange sealing surface shall be smooth and free of burrs; bolts shall be tightened evenly, and the exposed length of the bolts after tightening should not exceed 1  Pitch; gaskets shall be installed squarely, and the use of gaskets on the same sealing surface is strictly prohibited. 2  one or 2  More than one gasket.