Steel wire braided hoses, widely used flexible connecting elements in industrial fields, primarily function to enhance the compressive, tensile, and torsional resistance of the inner tube through a steel wire braiding layer, while maintaining the overall structural flexibility. However, in low-temperature environments, the molecular structure and mechanical properties of the material undergo significant changes, leading to decreased flexibility and even embrittlement and fracture, directly impacting the safety and reliability of the pipeline system. A thorough investigation into the mechanism by which low temperatures affect the flexibility of steel wire braided hoses and the proposal of targeted countermeasures are crucial for ensuring their stable operation under extreme conditions.
The decrease in flexibility of steel wire braided hoses at low temperatures mainly stems from the obstruction of molecular motion within the material. Inner tube materials (such as rubber, plastics, or composite materials) exhibit high molecular chain mobility at room temperature, enabling them to absorb external forces and deform through chain segment movement, thus demonstrating good flexibility. However, as the temperature decreases, molecular thermal motion weakens, chain segment mobility declines, the material gradually hardens, and the elastic modulus increases, resulting in a significant reduction in flexibility. If the temperature drops further below the ductile-brittle transition temperature of the material, the bonding force between molecular chains increases, the resistance to crack propagation decreases, and the material may transition from ductile fracture to brittle fracture, potentially breaking even under minor external forces.
The performance changes of the steel wire braided layer at low temperatures are also significant. As a reinforcement, the toughness of the steel wire is significantly affected by temperature. In low-temperature environments, the crystal structure of the steel wire may change, leading to increased yield strength and decreased toughness, manifested as weakened impact resistance. If the thermal expansion coefficients of the steel wire and the inner tube material do not match, interfacial stress may be generated during low-temperature contraction, causing the steel wire to debond from the inner tube or microcracks to initiate, further weakening the overall flexibility and load-bearing capacity of the hose.
To address the problem of decreased flexibility due to low temperatures, material modification is a key measure to improve the cold resistance of steel wire braided hoses. By optimizing the formulation of the inner tube material, its ductile-brittle transition temperature can be significantly reduced. For example, using highly elastic rubber or special plastics as the matrix material and adding modifiers such as plasticizers and cold-resistant agents can enhance the interaction between molecular chains and improve the material's flexibility at low temperatures. For the steel wire braided layer, alloy steels with excellent low-temperature resistance, such as nickel steel or austenitic stainless steel, can be selected. Their lattice structure maintains high toughness at low temperatures, thus delaying the embrittlement process.
Structural optimization design is another important way to improve the low-temperature performance of steel wire braided hoses. By adjusting the density, angle, and number of layers of the steel wire braid, the stress distribution of the hose can be optimized, reducing local stress concentration. For example, using a multi-layer cross-braid structure can enhance the hose's torsional resistance while avoiding overall failure due to the breakage of a single layer of steel wire. Adding a buffer layer, such as an elastomer or fiber composite material, between the inner tube and the steel wire braid can absorb the interfacial stress generated by low-temperature shrinkage, preventing debonding and microcrack propagation.
Insulation measures are an effective means of reducing the impact of low temperatures on steel wire braided hoses. By wrapping the hose with insulation materials, such as polyurethane foam, rubber-plastic insulation cotton, or glass fiber, the heat conduction of the low-temperature fluid to the hose can be reduced, maintaining the temperature stability of the inner tube and the steel wire layer. For extremely low temperature conditions, electric heating technology can be used, with an electric heating strip installed on the outer wall of the hose. This continuous, gentle heat transfer prevents material embrittlement caused by excessively low temperatures. Furthermore, a well-designed insulation layer thickness and structure can balance insulation effectiveness and cost, ensuring the hose's safety during long-term low-temperature operation.
Regular inspection and maintenance are essential for ensuring the low-temperature performance of steel wire braided hoses. In low-temperature environments, hose materials may develop defects such as aging and cracks due to long-term stress or environmental corrosion. Therefore, it is necessary to regularly inspect the hose's hardness, toughness, and surface condition, promptly identifying and replacing aging components. Simultaneously, the integrity of the insulation layer should be checked, and damaged or detached insulation material should be repaired to prevent performance degradation caused by localized excessively low temperatures. Establishing a comprehensive maintenance system can extend the service life of steel wire braided hoses and reduce the risk of failure under low-temperature conditions.
