The sealing structure design of a flange connector is a core element in preventing media leakage, and its reliability directly affects the safety and stability of the entire system. The design must comprehensively consider multiple dimensions, including sealing principles, structural form, material selection, processing technology, installation specifications, and maintenance management, to ensure the sealing structure remains effective under conditions of media pressure, temperature fluctuations, and mechanical vibration.
The design of the flange connector sealing structure must be based on the sealing principle of flange connections. A flange connector typically consists of a flange body, a gasket, connecting bolts, and nuts. Its sealing essence lies in the bolt preload causing the gasket to undergo elastic-plastic deformation, filling the tiny gaps between the flange sealing surfaces and preventing media penetration through the interface or capillaries. Therefore, the design must ensure that the gasket material has sufficient compression resilience to withstand the plastic deformation during preload and maintain sufficient residual clamping force under media pressure, preventing seal failure due to bolt creep or flange separation.
The selection of the flange connector sealing structure type must match the operating conditions. Common sealing surface types include flat surfaces, raised face surfaces, and tongue and groove surfaces. Flat surfaces have a simple structure but the gasket is easily extruded, making them suitable for low-pressure applications. Raised face surfaces restrict gasket displacement through the convex surface, making them suitable for medium-pressure environments. Tongue and groove surfaces place the gasket within a groove, allowing it to withstand higher pressures and providing a better seal, but with higher manufacturing costs. For high-temperature or corrosive media, tongue and groove or trapezoidal groove structures should be preferred, combined with metal or composite gaskets to enhance seal durability.
The choice of gasket material is crucial for preventing leakage. Gasket materials must be selected comprehensively based on the type of media, temperature range, and pressure rating. For example, non-metallic gaskets such as rubber and PTFE are suitable for low-pressure, normal-temperature conditions but have poor temperature resistance; metallic gaskets such as stainless steel and copper can withstand high temperatures and pressures but require surface treatment to improve corrosion resistance; semi-metallic gaskets such as spiral wound gaskets and metal-coated gaskets combine the strength of metals with the flexibility of non-metals, making them suitable for medium- and high-temperature conditions. Furthermore, the gasket thickness must be moderate; excessive thickness can lead to insufficient compression, while insufficient thickness may cause stress concentration and breakage.
The impact of machining accuracy on sealing performance cannot be ignored. The surface roughness, flatness, and perpendicularity of the flange sealing surface must be strictly controlled. Excessive surface roughness increases leakage channels, flatness deviations cause uneven stress on the gasket, and excessive perpendicularity may lead to localized stress concentration. CNC machine tools or specialized tooling must be used during machining to ensure that the geometric dimensions of the sealing surface meet design requirements. Rigorous inspection must be performed before assembly to avoid sealing failure due to machining defects.
The standardization of the installation process directly affects the initial sealing state of the sealing structure. During installation, bolts should be tightened gradually in a diagonal sequence to avoid excessive local preload, which could cause gasket displacement or breakage. Bolt preload must be evenly distributed and can be controlled using a torque wrench or hydraulic tensioner to ensure consistent force on all bolts. For high-temperature conditions, a certain compensation allowance should be reserved during cold installation to prevent bolt creep from reducing preload after heating. In addition, before installation, oil and impurities must be cleaned from the flange sealing surface and gasket surface to prevent foreign objects from embedding in leakage channels.
Maintenance and management are supplementary means to ensure the long-term effectiveness of the sealing structure. Regularly check for leaks at flange connections, which can be done visually, by listening, or with testing instruments. If a leak is found, the cause must be analyzed promptly, such as gasket aging, loose bolts, or damage to the sealing surface, and corresponding measures should be taken. For frequently opened and closed operating conditions, the inspection cycle should be shortened, and aged gaskets or bolts should be replaced or tightened when the equipment is shut down. For equipment that is not in use for a long time, it should be periodically rotated or purged with a protective medium to prevent corrosion or adhesion of the sealing surface.
The sealing structure design of the flange connector must be based on the sealing principle, combined with the operating conditions to select appropriate structural forms and materials. Through high-precision machining, standardized installation, and regular maintenance, a multi-layered leakage prevention and control system can be built. This process requires not only theoretical support but also the accumulation of practical experience. Only through continuous optimization of design parameters and process flows can a balance between the reliability and economy of the sealing structure be achieved.
