Flange connection method and process

As we all know, a flange is a component that connects between the shaft and the shaft, and is used to connect the two ends of the pipeline. Therefore, the method of connecting the pipeline with a flange is also called a flange connection. So, do you know that there are several ways of flange connection? What should be paid attention to when flange connection?

1. Flange connection

Flange connection can be divided into five types: flat welding, butt welding, socket welding, loose sleeve, thread. The first three types are described in detail as follows:

1. Flat welding: only the outer layer is welded, and the inner layer is not required to be welded. Generally used for the connection of medium and low pressure pipelines, the nominal pressure is lower than 2.5MPa. Flat welding flanges have three types of sealing surfaces, namely, smooth, concave and convex, and tongue-and-groove. Among them, the smooth type is widely used and has the characteristics of low cost and high cost performance.

2. Butt welding: The inner and outer layers of the flange should be welded, generally used for medium and high-pressure pipelines. The nominal pressure of the pipeline is between 0.25 and 2.5MPa. The sealing surface of the welded flange connection is uneven, the installation is complicated, the labor cost, and the installation method. And the cost of auxiliary materials is higher.

3. Socket welding: generally used for pipe connections with a diameter less than or equal to 40 mm.

Second, the process of flange connection

Although the flange connection methods are different, their connection process is not much different. The specific flange connection process is as follows:

1. Connection of flange and pipeline

The following requirements need to be met: the middle point of the pipeline and the flange should be on the same horizontal line; the middle point of the pipeline should be a 90-degree vertical shape, the sealing surface of the flange should be the same as the sealing surface of the flange; the flange bolts should be in the pipeline The positions on the top should be the same.

2. Gasket flange gasket

Requirements: In the same pipeline, the gaskets selected for flanges under the same pressure should be the same so that they can be exchanged in the future; the selection principle of gaskets should be as close as possible to the selection of small widths, that is, on the premise of not crushing the gaskets Should follow the principle of gaskets.

3. Connecting flange

Requirements: Check whether the specifications of flanges, bolts and gaskets meet the requirements; the sealing surface should be smooth and tidy without burrs; the bolt threads should be complete, without gaps, and the mosaic should be natural; the gasket texture should be flexible, not easy to age, and the surface No damage, wrinkles, scratches, etc.; before assembling the flange, clean the flange, oil, dust, rust and other debris, and remove the sealing line.

4. Assemble the flange

Requirements: The flange cover is perpendicular to the middle point of the pipeline; the installation direction of the bolts of the same specification is the same; the installation position of the flange installed on the branch pipe should be more than 100 mm from the outer wall of the riser, and the distance from the wall of the building should be more than 200 mm ; Do not bury the flange directly in the ground because it is easy to corrode.