In industrial piping systems, butterfly valves are widely used due to their compact structure, low cost, and ease of operation. However, the performance differences between soft-seated butterfly valves and metal-seated butterfly valves often lead to confusion during selection.
This article will analyze the core distinctions between the two types through four dimensions—sealing materials, temperature/pressure resistance, service life, and cost-effectiveness—and provide industry-specific selection recommendations.
– Sealing Materials: Elastic polymers such as EPDM, NBR, or PTFE.
– Seat Structure: Rubber/plastic seats form a flexible seal through direct contact with the disc.
– Typical Applications: Low-temperature, low-pressure environments with clean media (e.g., water, air, mildly corrosive liquids).
– Sealing Materials: Stainless steel, alloy steel, or Stellite-coated surfaces.
– Seat Structure: Metal-to-metal hard sealing, often designed with multi-layer or eccentric structures.
– Typical Applications: High-temperature, high-pressure environments or systems with abrasive/corrosive media.
– Zero Leakage: Achieves bubble-tight sealing (compliant with ISO 5208 Class VI standards).
– Cost-Effective: Material and manufacturing costs are 30–50% lower than metal-seated valves.
– Lightweight: Ideal for frequent on-off operations (e.g., >50 cycles per hour).
– Temperature Limits: EPDM seats withstand up to 120°C; PTFE up to 200°C.
– Poor Abrasion Resistance: Particles in media can scratch seals, causing leakage.
– Chemical Compatibility: Requires material-specific selection (e.g., NBR for oils, EPDM for acids/alkalis).
– Extreme Condition Resistance: Withstands temperatures up to 600°C (e.g., power plant boilers).
– High Abrasion Resistance: Suitable for media containing ash, slurry, or particles.
– Long Service Life: 3–5 times longer lifespan than soft-seated valves in harsh conditions.
– High Initial Cost: Precision machining and alloy materials double the price.
– High Torque Requirement: Requires larger actuators (e.g., pneumatic or electric drives).
– Minor Leakage: Metal seals typically have leakage rates around 10⁻³ mbar·L/s.
| Parameter | Soft-Seated Butterfly Valve | Metal-Seated Butterfly Valve |
| Max Temperature | 120°C (EPDM) / 200°C (PTFE) | 600°C (Alloy Steel) |
| Pressure Rating | PN10-PN16 | PN25-PN40 |
| Suitable Media | Water, gases, clean liquids | Steam,oils,abrasive/corrosive media |
– Municipal Water Supply: Low-pressure systems requiring low maintenance (e.g., water treatment plants).
– Food & Pharmaceutical: FDA-compliant PTFE seals to avoid contamination.
– HVAC Systems: Frequent adjustments in chilled/heating water circulation.
– Petrochemical: High-temperature oil pipelines (e.g., refinery distillation units).
– Power Plant Boilers: Steam pipelines and flue gas systems.
– Mining & Metallurgy: Slurry transport pipelines with abrasive particles.
A: No! High temperatures degrade rubber/PTFE seats. Use metal-seated valves with graphite gaskets.
A: Opt for multi-layer seals (e.g., triple eccentric design) or ultra-smooth sealing surfaces (Ra ≤ 0.4 μm).
A: Soft-seated valves allow easier seat replacement, but frequent repairs may offset initial savings. Metal-seated valves require less maintenance but higher repair costs.
A: Soft-seated valves achieve zero leakage for clean media. Metal-seated valves tolerate minor leakage (10⁻³ mbar·L/s) in extreme conditions.
A: Soft-seated materials degrade above 120–200°C. Metal seals withstand up to 600°C.
A: Wear, chemical corrosion, and thermal aging reduce rubber/PTFE seat life (3–5 years). Metal seats with Stellite coatings last 10+ years.
A: Metal-seated valves resist particle erosion; soft seats are easily damaged.
A: Soft-seated valves require lower torque, ideal for >50 cycles/hour (e.g., HVAC).
A:
– Mild corrosion (<20% concentration): Soft seats with FKM fluorocarbon.
– Severe/high-temperature corrosion: Metal seats with Hastelloy coatings.
1. Temperature > 200°C or abrasive media → Metal-seated valve
2. Clean media + budget constraints → Soft-seated valve
3. Frequent cycling → Prioritize soft-seated valves (reduces actuator load)
