Double eccentric butterfly valve is an industrial valve that achieves optimized sealing and wear resistance by deviating the valve stem axis twice. Its core features and applications are as follows:
1. Structural principle
Double eccentric design
First eccentricity: The valve stem axis deviates from the center of the butterfly plate to disperse the extrusion stress between the butterfly plate and the valve seat;
Second eccentricity: The valve stem axis deviates from the center of the valve body channel at the same time, so that the butterfly plate quickly leaves the valve seat when it is opened, reducing scratches and wear.
Sealing form
Elastic metal hard seal: Overlaying stainless steel (such as 1Cr18Ni9Ti) or Stellite alloy, temperature resistance ≤425℃, suitable for bidirectional medium flow;
Rubber/PTFE soft seal: Nitrile rubber valve seat is temperature resistant to 120℃, used in low-pressure scenarios such as water and gas.
2. Core advantages
Low friction and long life
The opening and closing process reduces scratches by 90%, and the valve seat life is increased by more than 3 times;
Modular valve seat replaceable design (such as Yuanda valve products) reduces maintenance costs.
Bidirectional sealing capability
Both forward and reverse media can achieve zero leakage (in compliance with API 598 standard), without installation flow direction restrictions.
Wide range adaptability
Diameter range: DN50~DN4000 (Newway valve can reach DN4000);
Pressure level: PN1.0~PN100 (Class 150~600).
3. Typical application scenarios
Infrastructure
Urban water supply and drainage trunk pipes (DN300 and above), building fire protection systems, relying on low flow resistance characteristics for energy saving; Industrial system
Ship ballast water/fuel pipelines (in compliance with GB/T 3037 marine standards);
Metallurgy, power medium-temperature media (≤425℃ flue gas, cooling water).
Restricted scenarios
Not suitable for high-pressure steam (＞Class 600) or highly corrosive media (such as concentrated sulfuric acid), in which case a three-eccentric butterfly valve should be selected.
4. Design and manufacturing standards
Structural specifications: API 609 (eccentricity parameters);
Material standards: valve body QT400-15 ductile iron, butterfly plate ZCuAl9Mn2 aluminum bronze alloy;
Performance test: shell test 1.5 times nominal pressure, seal test 1.1 times pressure.
Summary: Double eccentric butterfly valve balances sealing and durability through two axial offsets, making it the preferred valve for municipal, shipbuilding, and medium-temperature industrial pipelines, but it is inferior to the triple eccentric structure under extreme working conditions.