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Double Offset Butterfly Valve High Performance
Butterfly Valves

Double Offset Butterfly Valve – High Performance (HPBV)

The double offset (double eccentric) butterfly valve features two geometric offsets that create a cam-action seating mechanism. This reduces friction and wear, enabling higher pressure ratings and longer service life compared to concentric designs.

What is Double Offset?

1st Offset: Stem is positioned behind the disc centerline.
2nd Offset: Stem is offset from the pipe/body centerline.
This creates a cam effect that lifts the disc off the seat during opening, reducing wear.

Key Standards

API 609 Cat B BS EN 593 MSS SP-68 API 598

Size Range: DN50 to DN1200 (2" to 48") | Pressure: PN16 to PN40, Class 150-300

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Materials of Construction (MOC)

Component Material Specification
Body & Bonnet Ductile Iron (ASTM A536 / EN-GJS-400-15)
Stem / Spindle SS 410 / SS 420
Seat / Trim EPDM / NBR / Bronze

Technical Specifications

Parameter Specification / Standard
Manufacturing / Design Standard EN 1171 / AWWA C509 / BS 5163
Testing Standard API 598 / EN 12266-1
Pressure Rating PN16 / PN25

Frequently Asked Questions

What is a double offset butterfly valve?

A double offset butterfly valve (also called double eccentric or high performance butterfly valve) has two offsets: the stem is offset from the disc center (1st offset) and from the pipe/body center (2nd offset). This design reduces friction between disc and seat, minimizing wear and extending service life.

What is the difference between single and double offset butterfly valve?

A single offset valve has only one offset (stem behind disc center), while a double offset has two offsets (stem behind disc center AND offset from pipe center). Double offset provides cam-action seating, reducing seat wear and allowing higher pressure ratings up to PN40/Class 300.

What is API 609 Category B?

API 609 Category B covers high-performance butterfly valves designed for more demanding applications. These valves have offset disc design, can handle higher pressures (Class 150-600), and are suitable for throttling service. Category A covers general purpose concentric valves.

When should I use a double offset butterfly valve?

Use double offset butterfly valves when you need: higher pressure ratings (above PN16), longer service life, reduced maintenance, throttling applications, or when handling abrasive or particulate media. They are ideal for oil & gas, power plants, and chemical processing.

What is the maximum pressure for double offset butterfly valve?

Double offset butterfly valves can handle pressures up to PN40 (40 bar/580 PSI) or ANSI Class 300 (50 bar/720 PSI) depending on size and material. For higher pressures, triple offset butterfly valves are recommended.