double metallic expansion joint

Core Design & Components

1. Corrugated Metal Bellows: The flexible core element, typically made of stainless steel (304/316L) or high-nickel alloys (Inconel 625). Its corrugated structure enables angular deflection and withstands extreme temperature and pressure cycles.
2. Hinge Assembly: Consists of two pairs of hinge plates, pivot pins, and link bars. This mechanical constraint limits the joint to pure angular movement (no axial elongation/compression or lateral shift), preventing excessive stress on adjacent pipes or equipment.
3. End Flanges/Weld Ends: Standard connection interfaces (flanged for easy installation, welded for high-pressure sealing) that match pipeline specifications (ANSI, DIN, GB standards).
4. Internal Flow Liner (Optional): A smooth inner sleeve that reduces fluid/ gas turbulence, minimizes erosion to the bellows, and lowers flow resistance-ideal for pipelines transporting particulate-laden media.

Key Performance & Features

1. Angular Displacement Capacity: Each joint can accommodate angular deflection of ±5°-±15° (varies by bellows diameter and thickness). Multiple single hinged joints can be combined in a"hinged system"to handle complex multi-plane angular movements.
2. Temperature & Pressure Resistance: Operates reliably in temperature ranges from -200°C to 1000°C and pressure ratings up to 10 MPa, making it suitable for superheated steam, high-temperature oil, and corrosive gas media.
3. Structural Stability: The hinge assembly eliminates axial thrust generated by internal pressure, reducing the load on pipeline supports and anchors. This design prevents bellows overstretching or collapse under extreme operating conditions.
4. Fatigue Life: Meets EJMA (Expansion Joint Manufacturers Association) standards, with a minimum fatigue life of 10,000 cycles of temperature/pressure fluctuations, ensuring long-term operational reliability.

Typical Applications

• Power Generation: Main steam pipes, reheater pipes, boiler flue gas ducts, and SCR (Selective Catalytic Reduction) system pipelines.
• Petrochemical Industry: Refinery process pipelines, high-temperature reactor discharge lines, and heat exchanger connecting pipes.
• Metallurgical Industry: Blast furnace gas pipelines, steel mill steam pipelines, and smelting exhaust duct systems.
• Marine & Offshore: Ship engine exhaust pipelines, offshore platform process pipelines (resistant to salt spray corrosion).

Standards & Customization

• Design & Manufacturing Standards: EJMA, ASME B31.1/B31.3, GB/T 12777 (China national standard).
• Customization Options: Tailored bellows thickness, flange sizes, material grades (for corrosive media), and hinge pin materials (stainless steel for corrosion resistance, carbon steel for heavy-duty applications) to meet specific project requirements.

Installation & Maintenance Notes

1. Ensure the hinge assembly is aligned with the direction of expected angular movement; avoid forcing the joint beyond its rated deflection range.
2. Do not weld directly on the bellows surface; use protective covers during welding to prevent spatter damage.
3. Conduct periodic inspections (every 6-12 months) to check for hinge pin wear, bellows corrosion, or flange leakage; replace worn components promptly to avoid system failure.