Flange connection structure, sealing mechanism, type and shape

Release time:

2024-03-08

Flange is also called flange or flange. A part that connects the tube to the tube. Connect to pipe end. There are holes on the flange, and bolts can be worn to make the two flanges tightly connected. The flange is sealed with gasket.

flange

There are two types of connection between the components of the container: non detachable (welded) and detachable. Due to the requirements of production process, and for the convenience of manufacturing, transportation, installation and maintenance, detachable flange connection is often used between the cylinder and the cylinder, the cylinder and the head, the pipeline and the pipeline, and the pipeline and the valve. Although the detachable structure has the flange connection, the thread connection and the socket type connection and so on. However, flange connection is the most widely used in chemical and pharmaceutical equipment and pipelines due to its unique advantages of reliable sealing, high strength and wide range of application.

法兰连接的结构及密封机理

Structure and sealing mechanism of flange connection

Working mechanism: through bolt pre tightening, the gasket between the flange sealing surfaces is compacted and consolidated, and the uneven gap on the flange sealing surface is filled, which prevents the permeability leakage of medium through the rough hole in the gasket and the interface leakage between the gasket and the sealing surface. So as to achieve pre sealing.

The conditions to ensure that the flange connection seal does not leak are: when preloading, the preload specific pressure acting on the gasket shall not be lower than the preload specific pressure; when working, the residual specific pressure acting on the gasket shall not be lower than the working seal specific pressure.

法兰类型

Flange type

According to the integrity degree of flange and equipment or pipeline connection:

1、整体法兰

1. Integral flange

Flat welding flange: used for the occasion of low temperature and pressure. (there are specific temperature and pressure values in the standard)

Butt welding flange: applicable to important occasions with high pressure and temperature, toxic, flammable and explosive. High cost.

平焊法兰和对焊法兰的区别：

Difference between flat welding flange and butt welding flange:

1. Different weld forms: the weld of flat welding can not be radiographed, but the weld of butt welding can; flat welding is two fillet weld and butt welding is one butt weld.

2. Different nominal pressure: the nominal pressure of flat welding flange with neck is 0.6-4.0mpa, while the nominal pressure of butt welding flange with neck is 1-25mpa. Obviously, the applicable pressure level of flat welding flange with neck is lower.

3. Different connection methods: the flat welding flange can only be connected with the pipeline, but not directly with the butt welding pipe fittings; the butt welding flange can be directly connected with all butt welding pipe fittings (including elbows, tees, reducers, etc.), of course, including the pipeline.

2、松式法兰

2. Loose flange

Features: the flange fails to be connected with the pipeline or vessel, which is suitable for the occasion with low pressure, without additional bending stress for non-ferrous metal and stainless steel equipment and pipe shell; when made of carbon steel, it can save precious metal consumption. But the rigidity of loose flange is poor.

Connection mode of flange and vessel or pipeline: set on flanging, welding ring and Band Ring

3、螺纹法兰

3. Threaded flange

It is widely used in small diameter and high pressure pipeline, and the additional stress of flange to the pipe wall is small.

法兰的形状

Shape of flange

Generally speaking, the shape of the flange has the shape of a disc or a disc with a neck, and there are also some square or oval (waist). Square flange, round flange, oval flange