The DN500 hand-built NBR double-arch rubber expansion joint is a flexible piping component engineered with a face-to-face length of 350mm and an integrated ring-face sealing profile. The double-arch geometry is utilized to maximize multi-axial displacement capacity within a compact 350mm structural envelope, reducing geometric stiffness to lower the force required to deflect the joint. This configuration directly mitigates high-amplitude thermal expansion, structural settlement, and mechanical vibration, preventing excessive stress transfer to critical pumps, valves, and rigid piping headers.
The assembly is purpose-built for industrial wastewater transport systems operating under a maximum working pressure of 1.0 MPa within a temperature range of -20°C to 80°C. The specific combination of a hand-wrapped acrylonitrile-butadiene rubber (NBR) body and a split-ring floating mechanical flange configuration ensures localized structural integrity and dependable fluid containment under these specific environmental boundaries.
Key Engineering Features
- Hand-Built NBR Elastomer Core → Allows precise, continuous ply-alignment of internal reinforcement fabric without the material thinning or structural stress concentrations common in molded alternatives. The high-nitrile NBR compound provides chemical resistance against hydrocarbon-contaminated wastewater streams within the specified -20°C to 80°C thermal limits.
- Double-Arch Geometric Configuration → Distributes mechanical deflection across two distinct convolutions. This design reduces the spring rate of the rubber expansion joint relative to single-arch designs, allowing for greater structural compliance and vibration isolation per unit length.
- Integrated Ring-Face Seal Profile → Eliminates the requirement for separate gaskets by utilizing the molded elastomeric body as the sealing interface. The low-profile ring-face design concentrates the bolt-clamping force from the metal flanges to establish a gas- and liquid-tight seal against the mating pipe surface at 1.0 MPa.
- S235 Carbon Steel Floating Flanges (EN 1092-1 Type 02 Loose Flanges) → Simplifies field installation by allowing independent circumferential rotation of the metallic flanges. This design resolves bolt-hole misalignment issues common during retrofits or alignment with fixed equipment nozzles.
- Fusion Bonded Epoxy (FBE) Coating → Provides a barrier coating on the S235 carbon steel flanges. This surface treatment prevents galvanic corrosion and localized pitting when exposed to humid or corrosive industrial wastewater plant atmospheres.
- Removable Tie Rod Control Unit with Slip-On Ear Plates → Mounts directly onto the external flange perimeter to restrain pressure thrust forces under 1.0 MPa. This separate component design allows for simple assembly, structural adjustment, and full removal of the control rods during system inspections.
Applications
- Municipal Wastewater Treatment Facilities → Installed on the suction and discharge headers of low-pressure effluent transfer pumps to isolate mechanical vibration and accommodate piping misalignment.
- Industrial Fluid Piping Retrofits → Integrated into existing DN500 wastewater lines where fixed piping components require a flexible connection with floating EN 1092-1 flanges to match historical bolt patterns without line cutting.
- Industrial Wastewater Gravity and Low-Pressure Mains → Utilized in open or buried infrastructure transport lines handling raw or treated wastewater at pressures up to 1.0 MPa, accommodating soil shifting and localized thermal movement.
