Pipe flange is an indispensable part of the industrial pipe system, it is widely used in petroleum, chemical, power, natural gas, water supply and other industries, for connecting pipes and equipment or connecting points between different pipes. Flange connections usually need to rely on flange washers to achieve sealing, but whether the use of washers is a common technical discussion. This paper will discuss Are washers required on pipe flanges, and analyze its function, necessity, applicable scenarios and influencing factors.
Basic principles of flange connection
Flange connection is a method of fastening a flange to the flange surface of a pipe or equipment by connecting it with bolts. Since the flange itself is a flat metal surface, there may be slight unevenness or incomplete contact during the fastening process, which may cause leakage problems at the connection. Therefore, in order to ensure the sealing of the flange connection, gaskets are usually required.
Gaskets are sealing materials sandwiched between two flange surfaces, usually made of metal, rubber, graphite, polytetrafluoroethylene (PTFE) and other materials, with good flexibility and adaptability. When the bolts are tightened, the gasket will produce a sealing effect between the two flange surfaces to prevent medium leakage.
Function of gaskets
1. Sealing function: The most direct function is to form a seal through the compression of the gasket to prevent the fluid (such as gas, liquid, etc.) inside the pipeline from leaking out. This is the most common requirement for flange connection, especially under high pressure or high temperature conditions, gaskets are particularly important.
2. Compensation function: Since there may be slight unevenness on the flange surface, the gasket can effectively compensate for these unevenness and ensure close contact between the two flange surfaces.
3. Anti-vibration function: In some pipeline systems with large vibrations, the gasket can slow down the slight displacement caused by pressure fluctuations or external vibrations, and avoid leakage of flange connections due to vibration.
4. Corrosion resistance: Some special gaskets have good corrosion resistance and can be used in chemically reactive and corrosive media to extend the service life of pipeline connections.
Are washers required on pipe flanges
Whether to use gaskets depends on multiple factors, and the specific situation needs to be determined according to the actual working conditions. The following are several major considerations:
1. Medium properties: For media that require high sealing and are corrosive, flammable, explosive or high-temperature, the use of gaskets is particularly necessary. Flange connections without gaskets may cause media leakage, which may cause safety hazards. Therefore, the chemical properties, pressure, temperature, etc. of the medium are important factors in determining whether gaskets are needed.
2. Flange surface quality: When the flange surface flatness is good, sometimes the seal can be achieved by the tight fit between the metal flanges, and gaskets are not necessarily required. However, when the flange surface quality cannot be guaranteed to be completely flat, gaskets can play a compensatory role. Therefore, the manufacturing accuracy and surface finish of the flange have a direct impact on whether to use gaskets.
3. Pressure level: In high pressure or high temperature environments, the sealing performance of the gasket is crucial. If the pressure level of the flange connection is high, gaskets are usually required. On the contrary, under low pressure or normal temperature conditions, if the flange surface quality is good, or the connection does not need to be completely sealed, gaskets may not be used.
4. Flange type: Different types of flange connection methods may have different requirements for whether gaskets are required. For example, raised face flanges (RF) usually require gaskets to achieve good sealing, while flat flanges (FF) may form a seal directly through tightening force in some cases. It is worth noting that even for flat flanges, the use of gaskets is still a safer choice under some high temperature, high pressure or corrosive media.
5. Safety requirements: In some places with extremely high safety requirements, such as petrochemicals, nuclear power and other fields, gaskets are usually used to ensure the absolute sealing of flange connections to prevent accidents. Even if the flange surface precision is high, gaskets can still be used as a safety guarantee.
Alternatives to gasketless connections
Although gaskets play an important sealing role in flange connections, other methods can also be used to achieve the sealing of flange connections in some specific application scenarios, such as:
1. Metal-to-metal sealing: Some flange designs use metal-to-metal sealing methods, which achieve sealing by optimizing the design, precision and contact surface of the flange. This method may be more suitable in some high-temperature, high-pressure or highly corrosive environments.
2. Welded flange connection: In some occasions where extremely high sealing is required, welded flange connection is also a viable option. Directly connecting the flange to the pipe by welding eliminates the joints between the flanges and avoids the risk of leakage.
3. Use special sealing materials: In addition to traditional gaskets, materials such as coating seals and paste sealants can also be used, which can also achieve sealing effects under certain conditions.
Are washers required on pipe flanges depends on many factors, such as the nature of the medium, the quality of the flange surface, the pressure level, the flange type, etc. For most industrial applications, gaskets are indispensable as an effective means of achieving sealing, especially in pipelines with high pressure, high temperature or corrosive media. However, in some low-pressure, low-temperature or specially designed flange systems, it may be possible to achieve a sealing effect without using gaskets through alternative solutions such as optimized design, metal-to-metal sealing or welding. In general, the choice of whether to use gaskets should be based on specific working conditions and safety requirements.
