PTFE-lined metal hoses, with their excellent corrosion resistance, high-temperature resistance, and flexibility, are widely used in chemical, pharmaceutical, and food industries. However, improper installation can easily lead to delamination between the lining and the metal layer, causing media leakage or system failure. To avoid such problems, a comprehensive approach is needed, including pre-installation preparation, route planning, bend control, fixing methods, temperature management, welding protection, and post-installation inspection.
Before installation, a thorough inspection of the hose is required to confirm that its model, specifications, and length meet design requirements, and to check for any damage, cracks, or deformation. Obstacles along the laying path must be cleared to prevent sharp objects from scratching the lining. For direct burial outdoors, areas with stable geology and no corrosive media should be selected, and protective boards or fine sand pads should be laid in advance to reduce soil friction and pressure on the hose. Furthermore, the appropriate hose type should be selected based on the characteristics of the media; for example, high-temperature resistant hoses are used in high-temperature environments, and oil-resistant hoses are used in chemical environments.
Route planning is crucial to preventing lining delamination. The laying path should be as short and straight as possible, minimizing unnecessary bends and turns. When turning, use large-radius bends and avoid sharp or right-angle turns to reduce mechanical stress on the hose. For long-distance laying, plan the route in segments, with each segment's length controlled within a reasonable range to facilitate construction and subsequent maintenance. Simultaneously, consider the hose's elasticity, allowing for expansion and contraction space in environments with significant temperature variations to prevent tensile or compressive damage due to thermal expansion and contraction.
Controlling the bending radius directly affects the hose's mechanical properties. The minimum permissible bending radius of a PTFE-lined metal hose is typically more than 5 times the pipe diameter; the specific value needs to be determined based on the hose model and manufacturer's requirements. During laying, use specialized tools or molds to ensure that the hose's bending portion meets the minimum bending radius requirement, avoiding forced bending that could damage the internal structure. For complex routes requiring multiple bends, segmented laying or cable conduits can be used to guide the hose, reducing direct contact between the hose and obstacles.
The choice of fixing method is crucial to preventing liner peeling. PTFE-lined metal hoses should use appropriate fixing devices, such as specialized clamps or hanging devices, to securely fix them to supports or cable trays. The spacing between fixing points should be reasonably set according to the weight and length of the hose to avoid sagging or swaying due to insecure fixing. Simultaneously, the fixing device should meet the bending radius requirements of the hose and should not excessively squeeze or twist it. When laying vertically, a fall arrestor must be used to prevent internal damage caused by the hose's own weight stretching.
Temperature management is a crucial factor in ensuring the quality of hose installation. In low-temperature environments, PTFE material easily hardens and becomes brittle; the hose must be preheated to a suitable temperature before laying to avoid tensile damage due to material hardness and brittleness. In high-temperature environments, it is necessary to prevent the hose sheath from softening and deforming; shading or cooling measures should be taken if necessary. For hoses exposed to high-temperature environments for extended periods, high-temperature resistant PTFE material should be selected, and sufficient expansion space should be reserved during installation to prevent the inner lining from peeling off due to thermal expansion.
Welding operations are a critical step in the installation process that can easily damage the hose. If welding is required around the hose, effective protective measures should be taken, such as using fireproof cloth or baffles to shield the hose and prevent weld spatter from damaging the inner lining. Meanwhile, avoid welding or bringing the wire into contact with the hose to prevent burns to the lining or damage to the metal layer due to current flow. After welding, conduct a thorough inspection of the hose to ensure it is undamaged before putting it into use.
Post-installation inspection is crucial for ensuring the long-term stable operation of the hose. After installation, conduct a comprehensive inspection of the hose to confirm there is no tensile damage, twisting, or deformation. Simultaneously, use professional tools to check the adhesion between the lining and the metal layer to ensure there is no peeling or hollowing. During operation, regularly check the hose's fixation and appearance to promptly identify and address potential problems. For hoses subjected to significant mechanical stress over long periods, an online monitoring system can be installed to monitor stress and temperature changes in real time and provide early warnings of peeling risks.
