Butterfly valves are widely used in fluid control systems for their compact size, fast operation, and cost-effectiveness. But did you know that not all butterfly valves are built the same?
The two most contrasting types are the concentric and the triple offset (or triple eccentric) butterfly valves. At first glance, they might seem similar — after all, both feature a rotating disc that controls flow — but in reality, they’re designed for completely different performance levels and applications. So, what’s the difference between concentric and triple offset butterfly valves? Let’s break it down clearly and simply.
A butterfly valve is a quarter-turn valve that uses a rotating disc to start, stop, or throttle the flow of a fluid. When the disc is rotated 90°, the valve goes from fully open to fully closed.
These valves come in several designs based on how the disc is positioned and how it seals against the valve seat — and that’s where the terms concentric and offset come in.
A concentric butterfly valve, also known as a zero offset valve, is the most basic design.
The disc and shaft are positioned at the centerline of the valve body and pipe.
The disc rotates within a soft seat (usually rubber or elastomer), which provides a tight seal.
Simple and cost-effective design
Tight shut-off using soft materials
Lightweight and compact
Ideal for low-pressure and non-corrosive applications
HVAC systems
Water treatment
Irrigation
Food and beverage pipelines
General-purpose fluid control
A triple offset butterfly valve (also known as a triple eccentric valve) is a high-performance valve designed for critical, high-pressure, or high-temperature applications.
The disc and shaft are offset in three ways:
Shaft is placed behind the centerline of the disc seat.
Shaft is also offset from the pipe centerline.
The sealing surface is conical, allowing the disc to cam into the seat without friction.
Metal-to-metal sealing for high durability
No rubbing between disc and seat during operation
Handles extreme temperatures and pressures
Provides zero leakage (Class VI shut-off)
Fire-safe and corrosion-resistant with proper materials
Oil and gas pipelines
Chemical and petrochemical plants
Steam and power generation
Marine and offshore systems
Emergency shut-off valves (ESDVs)
| Feature | Concentric Butterfly Valve | Triple Offset Butterfly Valve |
| Offset Type | Zero offset (disc and shaft centered) | Triple offset (shaft & disc offset + conical seal) |
| Seal Type | Soft seal (rubber, PTFE) | Metal-to-metal seal |
| Sealing Action | Disc compresses elastomer seat | Torque seated, cam-action (no friction) |
| Friction During Operation | High (constant rubbing) | None (disc disengages seat during rotation) |
| Leakage Class | Class IV–V | Class VI (zero leakage) |
| Temperature Resistance | Low to moderate (up to ~200°C) | High (can exceed 500°C depending on material) |
| Pressure Rating | Low to medium | Medium to high (often > ANSI Class 600) |
| Durability | Moderate (seat wear is common) | High (minimal wear) |
| Cost | Low | Higher (premium performance) |
| Typical Applications | Water, HVAC, food-grade systems | Oil & gas, power, chemical, high-temperature processes |
The disc scrapes against the soft seat as it opens or closes.
This creates continuous friction, leading to wear and tear.
Over time, the soft seat may degrade or deform, requiring replacement.
The disc rotates away from the seat due to the triple offset design.
The conical sealing surfaces engage only at the final point of closure.
This eliminates rubbing, reducing maintenance and extending valve life.
Concentric valves are great for bubble-tight shut-off in clean, low-pressure systems. But in high-demand environments (e.g., steam lines or chemical transport), soft seals can fail under extreme conditions.
Triple offset valves shine in critical service where zero leakage and long service life are required. The metal-to-metal seat maintains integrity even in abrasive, corrosive, or high-temperature environments.
Let’s say you’re designing a municipal water pipeline. You probably don’t need the power of a triple offset valve — a concentric valve will do just fine and save money.
But if you’re dealing with superheated steam in a chemical refinery, a concentric valve would fail fast, leak, or catch fire. That’s when you reach for a triple offset.
| Part | Concentric Valve | Triple Offset Valve |
| Body | Cast iron, ductile iron, stainless steel | Stainless steel, carbon steel, duplex, Inconel |
| Disc | Stainless steel, bronze | Stainless steel, nickel-aluminum-bronze, hardened |
| Seat | EPDM, NBR, PTFE | Metal alloys (e.g., Stellite, Inconel) |
| Benefit | Concentric | Triple Offset |
| Affordable | ✅ | ❌ (More expensive) |
| Easy to install | ✅ | ✅ |
| Long-lasting in harsh env | ❌ | ✅ |
| Fire-safe | ❌ | ✅ |
| High-pressure capable | ❌ | ✅ |
| Frictionless operation | ❌ | ✅ |
The choice between concentric and triple offset butterfly valves comes down to your system's demands:
You're working with clean, low-pressure fluids
Cost and simplicity are key
You need a quick shut-off for non-critical services
You’re handling high-pressure, high-temperature, or hazardous media
You need metal-to-metal sealing and zero leakage
You want reliability and low maintenance in extreme environments
