Double-sphere expansion joint with pressurizing ring

The joint consists of an inner rubber layer, a multi-layer nylon cord fabric reinforcement layer, and an outer rubber layer, vulcanized and molded under high temperature and pressure, then assembled with metal flanges The pressurizing ring, typically constructed from multiple strands of steel wire or metal, is strategically placed between the two spheres to address the inherent structural limitations of double-sphere designs.

Key Benefits
Enhanced Pressure Resistance: The pressurizing ring strengthens the joint's ability to withstand high system pressures, preventing rupture or leakage under demanding operating conditions. This is particularly critical for large-diameter applications where internal pressure stress is more pronounced.

Superior Displacement Compensation: The double-sphere design provides exceptional compensation capabilities for axial extension and compression, lateral deflection, and angular displacement. This allows the joint to accommodate thermal expansion, contraction, and pipe settlement without compromising system integrity.

Vibration and Noise Reduction: The elastic rubber material effectively absorbs vibrations and dampens noise generated by fluid flow and mechanical equipment, protecting pumps, compressors, and other sensitive components .

Extended Service Life: By limiting radial expansion and controlling deformation under pressure, the pressurizing ring reduces rubber fatigue and aging. The reinforcing structure can improve the joint's aging resistance by over 30%, significantly extending its operational lifespan -10-5.

Corrosion and Wear Resistance: Available in various rubber compounds including EPDM, NBR, and Natural Rubber, the joint offers excellent resistance to a wide range of media including water, seawater, oil, acids, and alkalis 

Technical Specifications
Construction:

Inner rubber layer (various compounds available)

Reinforcement layer: high-strength nylon cord fabric

Outer rubber layer: weather and abrasion-resistant rubber

Pressurizing ring: steel wire or metal construction

Flanges: carbon steel, stainless steel, or ductile iron 

Performance Capabilities:

Axial compression: up to 35-60 mm depending on size

Axial extension: up to 30-35 mm

Lateral deflection: up to 45 mm

Angular deflection: up to 35° -1-6

Operating Parameters:

Pressure ratings: PN10, PN16, PN25 (1.0 MPa, 1.6 MPa, 2.5 MPa)

Temperature range: -15°C to 115°C (special materials available for -30°C to 250°C)

Applicable media: water, air, seawater, hot water, oil, acids, alkalis, and vacuum service

Why the Pressurizing Ring is Essential
During the manufacturing process of double-sphere joints, the structural configuration can result in insufficient rubber thickness between the two spheres, leading to reduced pressure-bearing capacity. The pressurizing ring directly addresses this design challenge by providing external reinforcement that prevents rupture under high pressure.

For large-diameter applications (DN300 and above), the pressurizing ring becomes even more critical. It evenly distributes pressure loads across the joint body, controls radial expansion that could cause flange bolt loosening, and prevents joint sagging caused by pressure fluctuations in thermal pipeline systems.