In low-temperature environments, the main challenge facing flange connectors is the increased brittleness of the materials, making them prone to brittle fracture under stress. This risk not only affects the normal operation of equipment but may also lead to safety accidents. Therefore, reducing the risk of brittle fracture in flange connectors at low temperatures through structural innovation is key to improving their reliability and safety.
The structural design of flange connectors must fully consider the material properties in low-temperature environments. Traditional connectors are prone to stress concentration due to material shrinkage at low temperatures. However, by optimizing the geometry of the flange, such as using rounded transitions or adding reinforcing ribs, stress can be effectively dispersed, reducing localized stress concentration. Furthermore, the connection between the flange and the pipe can be designed as a flexible structure, such as using bellows or expansion joints, to absorb displacement caused by low-temperature shrinkage and avoid stress accumulation caused by rigid connections.
The bolted connection is the core component of the flange connector, and its design directly affects the connector's resistance to brittle fracture. In low-temperature environments, bolt materials are prone to cold brittleness, leading to a decrease in preload or breakage. By using double-ended bolts or increasing the number of bolts, the load can be distributed, reducing the stress on individual bolts. Meanwhile, the contact surface between the bolts and the flange can be designed as spherical or conical to reduce stress concentration by increasing the contact area. Furthermore, using spring washers or disc springs can provide continuous preload compensation at low temperatures, preventing loosening due to material shrinkage.
The sealing structure is another crucial part of the flange connector, and its design must balance sealing performance and resistance to brittle fracture. Traditional sealing materials tend to harden or shrink at low temperatures, leading to seal failure. Using metal sealing rings or corrugated metal gaskets can replace non-metallic sealing materials, improving the low-temperature resistance of the sealing structure. In addition, the sealing surface can be designed as trapezoidal or wedge-shaped, achieving self-tightening sealing through mechanical compression, reducing reliance on sealing materials. Simultaneously, adding elastic elements, such as rubber O-rings or springs, to the sealing structure can compensate for material shrinkage at low temperatures, maintaining sealing performance.
The overall structural optimization of the flange connector needs to be approached from a system perspective, comprehensively considering the interaction of various components. For example, increasing the flange thickness or using a double-layer structure can improve its bending stiffness and reduce deformation caused by pipeline vibration or thermal expansion and contraction. Furthermore, the connection between the flange and the pipeline can be designed as a detachable structure, facilitating maintenance and replacement in low-temperature environments and reducing the risk of brittle fracture. Simultaneously, optimizing the overall connector layout and reducing unnecessary protrusions or recesses can lower the stress concentration factor and improve its resistance to brittle fracture.
Material selection and structural innovation complement each other and are crucial means of reducing the risk of brittle fracture in flange connectors. In low-temperature environments, materials with excellent low-temperature toughness, such as austenitic stainless steel or nickel-based alloys, should be prioritized. These materials maintain good ductility and impact resistance at low temperatures, effectively reducing the risk of brittle fracture. At the same time, surface treatment techniques, such as shot peening or nitriding, can further improve the surface hardness and fatigue strength of the material, enhancing its resistance to brittle fracture.
The manufacturing process has a significant impact on the brittle fracture resistance of flange connectors. In low-temperature environments, even minor defects during manufacturing, such as cracks, porosity, or inclusions, can become the starting point for brittle fracture. Therefore, strict control must be exercised over welding, heat treatment, and machining processes to ensure a defect-free flange surface. For example, using low-hydrogen welding electrodes or TIG welding methods can reduce the hydrogen content in the weld zone, lowering the risk of hydrogen embrittlement. Simultaneously, appropriate heat treatment processes, such as solution treatment or aging treatment, can refine the grains, improve the material's microstructure, and further enhance its low-temperature toughness.
Reducing the risk of brittle fracture in flange connectors at low temperatures through structural innovation requires a comprehensive approach, encompassing geometric optimization, bolt connection design, improved sealing structures, overall structural optimization, material selection and surface treatment, and manufacturing process control. These innovative measures not only improve the reliability and safety of flange connectors at low temperatures but also extend their service life, reduce maintenance costs, and provide strong support for the stable operation of industrial equipment.
