A flange is a pipe fitting used to connect pipes, valves, pumps, and other equipment in a piping system. It provides a flat or raised surface that can be bolted to a matching flange, creating a connection that is strong, sealed, and easy to assemble or disassemble. Flanges are widely used in petroleum, chemical, power, heating, water supply and drainage, gas, and various industrial piping systems.
In piping systems, some connections need to be strong and sealed, while also allowing for easy disassembly, inspection, or maintenance. A flange connection provides a practical solution. By using bolts to join two flanges together, the piping system can be assembled and disassembled more conveniently, and the connection can be designed to meet different pressure and temperature requirements.
A flange usually consists of the following parts:
Body
The body is the main part of the flange. It is usually made of metal or other suitable materials, depending on the medium, temperature, pressure, and installation environment. The body provides the basic shape and strength of the fitting.
Bolt Holes
Bolt holes are arranged around the flange body. They are used to pass bolts through and connect the flange to a matching flange. The number and size of bolt holes depend on the flange size and pressure rating.
Sealing Face
The sealing face is the surface that contacts the matching flange. It may be flat, raised, or grooved, depending on the sealing requirements. The sealing face plays an important role in preventing leakage.
Connection End
The connection end is used to connect the flange to a pipe, valve, or equipment. Common connection methods include welding, threading, and integral casting or forging.
Surface Treatment (in some cases)
Depending on the application environment, flanges may be provided with surface treatment such as anti-corrosion coating or other protective layers.
First, strong and sealed connection.
A flange connection uses bolts to join two flanges together, providing a strong and sealed connection for pipes and equipment.
Second, convenient assembly and disassembly.
Flange connections can be assembled and disassembled more conveniently than some other connection methods, which is useful for inspection and maintenance.
Third, various types available.
Flanges can be supplied in different types to match different piping systems, pressure levels, and installation requirements.
Fourth, material options.
Depending on the medium and working conditions, flanges can be made from different materials to meet requirements for strength, corrosion resistance, and temperature resistance.
Fifth, suitable for different pressure levels.
Flanges can be selected according to the pressure rating of the piping system, helping to ensure safe and reliable operation.
Sixth, widely used.
Flanges are used in many industries, including petroleum, chemical, power, heating, water supply, drainage, gas, and general industrial piping.
Flanges can be classified into different types according to structure, connection method, and application. Common types include:
Weld Neck Flange
A flange with a long tapered neck that is butt welded to the pipe. It is often used in high pressure and high temperature piping systems.
Slip-On Flange
A flange that slips over the pipe and is then fillet welded. It is relatively easy to install and is used in various piping systems.
Socket Weld Flange
A flange that is socket welded to the pipe. It is often used in small diameter and high pressure piping systems.
Threaded Flange
A flange that is connected to the pipe by threads. It is often used in small diameter piping systems where welding is not convenient.
Lap Joint Flange
A flange that works together with a lap joint stub end. It can rotate freely around the stub end, making alignment easier.
Blind Flange
A flange without a center hole, used to close the end of a pipe or a connection point.
Plate Flange
A flat, circular flange with a center hole and bolt holes. It is often used in low pressure piping systems.
Different types of flanges have different characteristics in terms of structure, connection method, pressure rating, and application. When selecting a flange, factors such as medium, temperature, pressure, connection method, installation space, and relevant standards should be considered.
Flanges are widely used in the following fields:
Oil and gas pipelines;
Chemical and industrial process pipelines;
Power plant piping systems;
Heating and steam pipelines;
Water supply and drainage pipelines;
Gas transmission pipelines;
Other piping systems requiring flanged connections.
In these applications, flanges usually work together with pipes, valves, pumps, compensators, and supports to ensure the stable operation of the piping system.
A flange is not a universal fitting. Selection should be based on the specific working conditions of the piping system. The following points are usually considered:
Type
Determine whether a weld neck, slip-on, socket weld, threaded, lap joint, blind, or plate flange is required based on the system design.
Size
The flange size should match the pipe size and the matching flange.
Pressure Rating
The flange pressure rating should match the design pressure of the piping system.
Medium
Consider whether the medium is gas, liquid, steam, or a mixture, and whether it is corrosive.
Temperature
The operating temperature of the piping system affects the material and structure selection of the flange.
Connection Method
The connection method should match the design of the piping system and installation requirements.
Material
Choose a suitable material according to the medium, environment, and working conditions.
Standards and Specifications
The flange should meet the requirements of relevant standards and specifications to help ensure product quality and safe use.
To ensure the flange works properly in the piping system, the following points should be noted during installation and use:
Follow technical documents and standards.
Read the product technical documents and relevant specifications carefully before installation, and operate according to the requirements.
Ensure connection quality.
The connection between the flange and the pipe should be carried out according to the process requirements to ensure sealing and strength.
Check sealing face.
Before assembly, check the sealing face for damage, scratches, or foreign matter, and clean it if necessary.
Tighten bolts properly.
Tighten bolts in the correct sequence and to the required torque to help ensure even pressure and good sealing.
Protect the surface.
During transportation, storage, and installation, protect the flange surface from collision, scratches, or deformation.
Regular inspection and maintenance.
After commissioning, regularly check the appearance, connection parts, and sealing condition of the flange. If any abnormality is found, handle it in time or contact professionals for judgment.
