1. Selection of High-Temperature Resistant Materials

• Stainless Steel Alloys:
  • 304/304L Stainless Steel: Suitable for ≤650°C, with good oxidation and corrosion resistance.
  • 316/316L Stainless Steel: Contains molybdenum for better high-temperature performance (≤700°C) and enhanced chloride resistance.
  • 321 Stainless Steel: Stabilized with titanium to prevent intergranular corrosion at high temperatures (≤800°C).
• High-Temperature Alloys:
  • Hastelloy (e.g., C-276): Withstands extreme temperatures (≤1200°C) and strong corrosion, ideal for chemical and energy industries.
  • Inconel (e.g., 600/625): Maintains high strength above 900°C with excellent oxidation resistance.
• Nickel-Based Alloys:
  • Incoloy 800H resists creep at ≤950°C, widely used in high-temperature steam pipelines.

2. Structural Design for High-Temperature Resistance

• Multi-Layer Bellows Structure:
  Composed of 2–5 layers of thin metal sheets (0.1–0.5mm thickness), forming:
  • Reduced thermal stress concentration in single layers.
  • Insulation via air gaps between layers, enhancing flexibility and fatigue resistance.
• Optimized Corrugation Parameters:
  • Increased wave height and pitch expand thermal expansion space, reducing thermal load per unit area.
  • 'U-shaped' or 'Ω-shaped' corrugations distribute stress more uniformly than 'V-shaped' for stable high-temperature deformation.
• Built-in Thermal Insulation Linings:
  Welded or adhered ceramic fiber, refractory bricks, or metal mesh linings (e.g., alumina fiber) on the inner bellows surface block direct high-temperature medium contact, reducing surface temperature.

3. Thermal Stress Relief and Compensation Mechanisms

• Directional Compensation Design:
  Select axial/lateral/angular compensators based on pipeline thermal expansion direction to avoid structural damage from constrained displacement.
• Pre-Stretching/Pre-Compression Installation:
  Apply pre-deformation opposite to thermal expansion during installation to offset displacement and reduce stress peaks under operating conditions.
• Guided Support Collaboration:
  Install guide supports at both ends to limit non-compensated direction displacement, ensuring thermal expansion follows the designed path and preventing bellows twisting.

4. Surface Treatment and Protection Measures

• Anti-Oxidation Coatings:
  Spray high-temperature ceramic coatings (e.g., zirconia ZrO₂) or metal plating (e.g., nickel-chromium alloy) on the bellows surface to form an oxidation barrier and extend material life.
• Heat Dissipation Structures:
  For extreme temperatures (≥1000°C), design external heat dissipation fins or water-cooling channels to reduce bellows temperature via forced cooling.

5. Typical Application Scenarios and Temperature Ranges

Conclusion