As an important component for connecting pipes, valves, pumps and other equipment, flanges are widely used in industries such as oil, natural gas, chemical industry, water supply and drainage, electricity, and shipbuilding. Correct installation of flanges is essential to ensure the sealing, stability and safety of the pipeline system. This article will introduce the types of flanges, preparations before installation, precautions during installation, and inspection and maintenance after installation.
How should flanges fit?- Types and selections
Flanges can be divided into the following types mainly according to their connection methods, shapes and uses:
1. Flat welding flange: Commonly used in low-pressure pipeline systems, its connection method is simple and the welding strength is low.
2. Butt welding flange: used for medium and high pressure pipelines, with high bearing capacity and sealing.
3. Threaded flange: connected by thread, suitable for pipelines with smaller diameters, simple installation.
4. Socket flange: suitable for large-diameter pipelines, one end of the flange is inserted into the pipeline, and the other end is connected by bolts.
5. Blank flange: used to close both ends of the pipeline, usually used for maintenance or blocking certain pipelines.
According to the actual working conditions and the specifications of the pipeline, it is very critical to choose the right flange type. If the selection is inappropriate, it may cause failure or leakage of the pipeline system.
Preparations before installation
1. Inspection of flanges
Before installing the flange, the quality of the flange itself must be checked to ensure that there are no cracks, deformations, corrosion or other damage. Especially the sealing surface, make sure it is flat and free of defects. Any dirt or oil on the sealing surface will affect the sealing effect and even cause leakage.
2. Inspection of pipelines
Check the ports of the pipeline to ensure that there are no burrs, cracks, deformations, etc. at the ends of the pipeline. The pipeline port should be flat and fit well with the flange. If the pipeline port is not flat, it can be trimmed with tools such as lathes and grinders.
3. Selection and inspection of gaskets
The sealing gaskets of flange connections play a vital role. The appropriate gasket materials should be selected according to the characteristics, working pressure and working temperature of the medium transported by the pipeline. Common gasket materials include metal gaskets, non-metallic gaskets, composite gaskets, etc. Check the quality of the gaskets before installation to avoid using aging and damaged gaskets.
4. Preparation of tools and equipment
When installing flanges, you need to prepare some common tools and equipment, such as wrenches, gasket knives, cleaning tools, torque wrenches, etc. During the installation process, make sure all tools are present and in good condition.
How should flanges fit
1. Clean the contact surface between flange and pipe
Before installation, clean the contact surface between flange and pipe to remove oil, dust and other impurities. You can use a clean cloth or detergent to wipe it to ensure that the contact surface is clean and flat.
2. Placement of gasket
Place the gasket between the sealing surface of the flange and the port of the pipe to ensure that the gasket is in the correct position without offset or damage. If it is a multi-layer gasket, make sure that each layer of gasket is laid neatly.
3. Docking flange and pipe port
Align the flange with the pipe port and ensure that the hole position of the flange is aligned with the hole of the pipe port. When docking, avoid tilting the flange to prevent uneven pressure distribution and affect the sealing effect.
4. Tighten the bolts
The connection of the flange is usually completed by bolts. Tighten the bolts on the flange in a diagonal sequence to ensure uniform pressure. When tightening, gradually increase the torque to avoid over-tightening at one time, causing flange deformation or gasket damage.
5. When initially tightening, the torque should be small, and all bolts should be tightened to a uniform initial position first.
Then, gradually increase the torque to ensure that each bolt is tightened evenly.
6. Use a torque wrench to calibrate the torque
To ensure that the tightening force of the flange connection meets the design requirements, a torque wrench can be used to check and calibrate the torque value. Excessive or insufficient torque may affect the sealing and safety of the flange connection.
7. Check the flange connection
After installation, check whether the flange connection is well sealed. The sealing effect of the flange can be checked by gas leak detection, liquid pressure test, etc. If leakage is found, it should be adjusted or reinstalled in time.
Inspection and maintenance after installation
1. Check the tightness of the bolts
After the flange is connected, the tightness of the bolts should be checked regularly to ensure that the bolts are not loose. Especially in the early stage of the operation of the pipeline system, the tightness of the bolts should be checked regularly for a period of time.
2. Check the sealing surface regularly
Since the pipeline system is in a working environment with pressure and temperature changes for a long time, the sealing surface of the flange may change. Therefore, the sealing surface of the flange should be checked regularly, and the flange or gasket should be replaced in time when problems such as wear and deformation are found.
3. Prevent corrosion and external damage
The connection between the flange and the pipeline is easily affected by the external environment, resulting in corrosion or damage. Anti-corrosion measures should be taken, such as coating anti-corrosion paint, wrapping insulation materials, etc., to avoid environmental factors from causing adverse effects on the flange connection.
The correct installation of the flange is not only related to the sealing of the pipeline system, but also directly affects the safety and stability of the system. By carefully selecting suitable flanges and gaskets, strictly following the installation steps, and regularly checking and maintaining, the sealing performance of the flange connection and the long-term operation of the system can be effectively ensured. Every detail may affect the final effect. Therefore, the installation of the flange needs to be strictly controlled to ensure that every link is in place.
