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Views: 0 Author: Site Editor Publish Time: 09-26-2025 Origin: Site
Working principle
A spherical rubber expansion joint uses a spherical convoluted body to accept axial, lateral, and angular movements while isolating vibration and attenuating noise. The rubber body consists of liner → reinforcement plies → wire reinforcement rings → outer cover, and is sealed between flanges. Tie rods can limit tensile movement and carry pressure thrust; vacuum rings prevent collapse under negative pressure.
Single vs. Double sphere
• Single sphere: compact, higher pressure rating, higher stiffness, moderate movement capability — ideal at pump suction/discharge or tight spaces.
• Double sphere: two spheres in series offering greater movement and lower dynamic stiffness (better NVH), but typically lower pressure rating than single sphere.
Rule of thumb: choose double sphere when total movement >10–15 mm or NVH control is critical; choose single sphere when pressure ≥ PN16 / ANSI 150 or negative pressure is frequent (add tie rods and vacuum ring).
Typical applications
• Pump suction & discharge: absorb surge and pump vibration.
• HVAC chilled/heating water: compensate thermal growth and reduce building-borne noise.
• Municipal wastewater & stormwater: EPDM/CSM for microbial & sludge environments.
• Seawater/desalination/salt-fog: CSM liner + stainless flanges.
• General chemical services: select liner by medium after compatibility checks.
Takeaway: Movement and pressure define the Single/Double choice; tie rods and vacuum rings are boundary safeguards.
Next step: Gather movement, pressure, temperature, and medium data, then follow the selection workflow.
Required inputs
• Size (DN / Inch) — match the pipeline.
• Pressure rating — design pressure & flange class (ANSI 150# / PN10 / PN16).
• Temperature — min/max service temperature.
• Medium — water, wastewater, seawater, oil, mild acids/alkalis, glycol, etc.
• Movement — axial compression/elongation (±ΔL), lateral offset (Y), angular deflection (θ°).
• Vacuum & anchoring — expected negative pressure (mbar/kPa); fixed anchors available?
Movement check (example)
Thermal growth of steel pipe: ΔL = α × L × ΔT (α_steel ≈ 12×10⁻⁶ per °C). Required axial compression ≥ ΔL. When lateral/angle also occur, derate each allowable value per combined movement curves (simultaneous movements reduce single-axis allowances). Double sphere allows more movement than single sphere, but at lower pressure.
Thrust & anchoring
Rubber expansion joints must not carry blind-flange thrust from internal pressure. Approximate axial force: F ≈ P × A, where A = π·D⊃2;/4. Example: DN200 (ID ≈ 204 mm), P = 1.6 MPa → A ≈ 0.0327 m² → F ≈ 52 kN. Provide fixed anchors and pipe supports on both sides; use tie rods to limit elongation and resist transient forces.
Guide spacing (good practice)
First guide ≈ 4D downstream; second ≈ 14D; subsequent ≈ 14D each (adjust per layout and stiffness).
Takeaway: Selection is a system exercise—movement + pressure + thrust + anchoring + guiding.
Next step: Send your movement and thrust worksheet for a sphere type and tie-rod preset recommendation.
Body construction
Liner (medium/temperature) → reinforcement plies (pressure) → wire rings (vacuum) → outer cover (ozone/UV/abrasion).
Elastomer comparison
Material | Typical temperature | Chemical resistance | Vacuum/negative pressure | Notes / Recommendations |
EPDM | −40 to 120 °C (short 130 °C) | Hot/chilled water, condensate, mild acids/alkalis | Good | HVAC, wastewater, municipal; not oil-resistant |
NBR | −20 to 100 °C (short 110 °C) | Oils/fuels/lubricants | Medium | Oil service, oily waste streams |
CSM | −25 to 110 °C | Seawater/salt spray/broad chemical mix | Good | Marine/desalination/chemical general duty |
NR | −30 to 90 °C | Water/air | Medium | Cost-effective; abrasion good; poor ozone resistance |
Flanges: carbon steel (painted/galvanized/e-coated), stainless 304/316, ductile iron; epoxy/powder/hot-dip galvanizing coatings optional.
Takeaway: Medium & temperature determine the liner; wire rings + vacuum ring protect under negative pressure.
Next step: Share medium/temperature/oil/salt/chemical data for compound matching.
Model | DN (mm) | Inch | Type | Pressure | Axial comp. | Axial elong. | Lateral | Angular | Vacuum* |
HM-S100-PN16 | 100 | 4" | Single | PN16 / ANSI 150# | 12 mm | 8 mm | 10 mm | 12° | −0.085 MPa (with ring) |
HM-S150-PN16 | 150 | 6" | Single | PN16 / ANSI 150# | 15 mm | 10 mm | 12 mm | 12° | −0.085 MPa |
HM-D200-PN10 | 200 | 8" | Double | PN10 / ANSI 150# | 22 mm | 14 mm | 18 mm | 15° | −0.06 MPa |
HM-D250-PN10 | 250 | 10" | Double | PN10 / ANSI 150# | 25 mm | 16 mm | 20 mm | 15° | −0.06 MPa |
Standard sizes: DN25 (1") – DN600 (24"); larger on request. Flange standards: ANSI 150#, DIN PN10/PN16, EN 1092-1 (Type B1/B2).
Takeaway: Single = compact & higher pressure; Double = more movement & lower stiffness. For vacuum, add the vacuum ring.
Next step: Download the spec sheet (PDF) or send size + movement for drawings and samples.
• Align first: pipe ends coaxial and parallel; do not use the joint to correct misalignment.
• Clean flange faces; in most cases the rubber bead seals without a separate gasket (follow product BOM).
• Use cross/star pattern tightening; torque in stages.
DN | Bolt size | Torque (Nm) | Notes |
50–80 | M16 | 45–60 | ANSI 150/PN16 |
100–150 | M16/M20 | 60–100 | Class 8.8 |
200–250 | M20 | 100–140 | Class 8.8 |
300–400 | M20/M24 | 140–220 | Class 8.8 |
• Retighten after 24–48 h in service (or after hot run), cross-pattern.
• No torsion: avoid twisting or pre-stretching the sphere.
• Tie-rod setup: set length to installed face-to-face; tighten nuts to “snug + lock”.
• Vacuum service: for continuous/frequent negative pressure (suction/high points), install a vacuum ring oriented correctly.
Takeaway: Alignment + star-pattern torque + hot retightening maximize life; vacuum/tension risks handled by vacuum rings & tie rods.
Next step: Request the Installation & Torque Card (PDF).
Common issues
• Bulging/collapse — vacuum without ring or inadequate guiding.
• Leakage — uneven flanges, non-uniform bolt load, wrong gasket scheme.
• Early cracking — wrong elastomer for medium/temperature; UV/ozone attack.
• Pull-out — no anchors to resist pressure thrust; severe water hammer.
• Lateral wear marks — lack of guides; sustained shear.
Maintenance
• Retighten after first hot run; inspect every 3–6 months.
• Check tie-rod nuts and anti-loose devices.
• Sun-shade/splash guards outdoors.
• With correct material & installation, design life typically 5–10 years (duty-dependent).
Takeaway: ~80% of failures trace to anchoring/guiding/material choice. A simple inspect + retorque routine minimizes risk.
Next step: Send site photos and duty details for RCA and replacement proposals.
• TÜV/ISO quality systems; batch traceability and compound control.
• Full standards: ANSI 150#, DIN PN10/PN16, EN 1092 flanges.
• Elastomers: EPDM/NBR/CSM/NR, Shore A 55–70 matched to medium.
• Engineering: tie-rod & vacuum solutions; thrust & anchor calculations.
• Delivery: rapid prototyping + small MOQs; flexible OEM/private label.
Next step (CTA): Request Samples | Get a Quote | Talk to an Engineer
SEO Title: Sphere Flexible Rubber Expansion Joints (Single/Double, Flanged) | ANSI 150 / PN10 / PN16 | EPDM/NBR/CSM | Hebei Huami
Meta Description: Huami supplies single/double sphere rubber expansion joints with ANSI 150#, DIN PN10/PN16, EN 1092 flanges. Elastomers EPDM/NBR/CSM/NR (Shore A 55–70). Tie rods & vacuum rings optional. Includes selection, movement & thrust calculations, installation torque, and maintenance. Rapid prototyping & small lots.
URL Slug: /products/sphere-rubber-expansion-joints
Open Graph: title/description as above; image /images/sphere-rubber-expansion-joint-01.jpg; type product.
Q: How do I choose between single and double sphere?
A: Pick double for larger movement and lower NVH; pick single for higher pressure/vacuum and compact layouts.
Q: Do I need separate gaskets?
A: Follow the BOM; the rubber bead typically seals to the flange without extra gaskets.
Q: Are tie rods required?
A: Recommended where water hammer occurs or anchors are absent; tie rods limit extension and take thrust.
Q: When is a vacuum ring mandatory?
A: On suction lines or systems with frequent negative pressure (≈ ≤ −0.06 MPa) to prevent collapse.
Q: How do I estimate anchor thrust?
A: Use F ≈ P × A, with A being the pipe cross-sectional area.
Q: Is it suitable for seawater or chemicals?
A: Use a CSM liner and stainless flanges after compatibility verification.
Q: What temperature limits apply?
A: EPDM up to 120–130 °C, NBR 100–110 °C, CSM 110 °C, NR 90 °C (typical).
Q: Lead time & MOQ?
A: Common sizes stocked; rapid sampling and small-lot manufacturing supported.
