Concentric, Double Offset & Triple Offset Flanged Butterfly Valves: Suitable and Unsuitable Working Condition Comparison

Flanged butterfly valves are widely used in water treatment, HVAC, power, petrochemical and industrial fluid pipelines. According to structural design, they are mainly divided into concentric, double offset and triple offset types. Many purchasers confuse the three structures and select improper models, resulting in seal aging, leakage and short service life. Each structure has unique sealing characteristics, temperature and pressure adaptability. This article compares their applicable and unsuitable working conditions to support accurate engineering selection.

Concentric flanged butterfly valve

The valve shaft is concentric with the disc and sealing surface. It mostly adopts soft rubber seat such as EPDM and NBR.

✅ Suitable conditions: Normal temperature, low-pressure clean water, sewage, HVAC circulating water, fire protection pipelines; nominal pressure PN6/PN10/PN16.

❌ Unsuitable conditions: High temperature, high pressure, oil media, strong corrosive fluid, frequent switching occasions. Long-term high temperature will cause rapid aging of rubber sealing.

Double offset flanged butterfly valve

The first offset deviates the shaft from the disc center; the second offset separates the shaft from the sealing plane. The disc leaves the seat quickly when opening, reducing friction with the seal. Soft seat and metal hard seal versions are available.

✅ Suitable conditions: Medium temperature and medium pressure pipelines, industrial water, light oil, weak corrosive medium; scenarios requiring frequent opening and closing.

❌ Unsuitable conditions: Ultra-high temperature, strong acid and alkali, strict zero-leakage requirements under high pressure.

Triple offset flanged butterfly valve

Based on double offset, the third offset forms an inclined conical sealing surface. It mostly adopts metal-to-metal hard seal. No friction between disc and seat during opening and closing.

✅ Suitable conditions: High temperature, high pressure, steam, thermal oil, petrochemical media; working conditions demanding reliable tight shutoff.

❌ Unsuitable conditions: Low-cost conventional water supply projects with low budget; media containing large hard particles which easily scratch metal sealing surfaces.

In practical selection, medium temperature, pressure, chemical property and leakage standard are decisive factors. Concentric butterfly valves are cost-effective for conventional municipal water systems. Double offset types balance service life and cost for general industrial pipelines. Triple offset metal-seated butterfly valves are preferred for high-temperature and high-pressure industrial processes.

Wrong structure selection will cause continuous maintenance cost increase. Matching the offset structure with actual working conditions can effectively guarantee sealing performance and extend valve service cycle.