5-offset metal-seated butterfly valves — zero leakage from cryogenic to high temperature
The 5-offset butterfly valve — also called the penta-offset or quintuple-offset valve — is a metal-seated quarter-turn valve for tight shut-off where the seal between disc and seat must stay leak-tight across an exceptionally wide temperature range. EURAD supplies and advises on it for the most demanding duties; this note sets out the sealing principle and what it is built for.
The penta-offset sealing principle
Five offsets in the shaft-disc positioning and seat geometry combined let the disc rotate clear of the seat through almost the entire stroke and meet it only in the final fraction of closing. Seat and disc then seal metal-to-metal without sliding contact, so there is effectively no wear on the sealing faces — the valve holds its tightness over a long service life and a high number of cycles.
Tight across expansion and contraction
A metal-to-metal seal holds tight under cold and hot operating temperatures and temperature cycles only if the seat and the disc seal contract and expand to the same degree across the complete sealing surface — contracting uniformly at cryogenic temperature and expanding uniformly at high temperature. The penta-offset geometry gives the seat and the disc seal a consistent, circular form, so they expand and shrink in a linear, uniform way regardless of valve size or temperature. The sealing surface stays tight across the full range — from high-temperature service down to liquefied-gas and cryogenic duty such as LNG and hydrogen.
Bidirectional, metal-to-metal shut-off
The valve seals fully rated in both flow directions, metal-to-metal, to zero-leakage classes such as EN 12216 class A and API 598 — and holds that tightness at both cryogenic and high temperature. There is no soft seat to degrade with temperature, ageing or media, which is what makes the metal seat usable where elastomers cannot be.
Low torque and floating-disc operability
A floating-disc design keeps operating torque low, including at high pressure, and tolerates fast temperature changes. Actuator sizing stays modest and operation stays predictable under thermal cycling.
Seat and seal options per duty
Sealing is matched to medium and temperature: metal lamination for steam, a silver-coated Inconel O-ring for high-temperature, cryogenic and oxygen duty, and metal or PTFE options for aggressive or clean chemical service. Seat hardfacing such as Inconel or Stellite is selected to the application.
Duty envelope
Available across a broad size and pressure range, applicable for regular and extreme process conditions, with an all-metal construction option and fire-safe execution. Temperature capability spans cryogenic through high-temperature service. Exact size, class, materials and certification are set per project.
Where EURAD applies the 5-offset
EURAD specifies the 5-offset metal-seated butterfly valve where tight shut-off must survive demanding conditions: cryogenic and liquefied-gas service, high-temperature and thermal-cycling duty, and oxygen service. See the related application notes below for those duties.
Selection per situation
The right configuration depends on medium, temperature, pressure class and the applicable leakage and certification regime. Share those and EURAD advises on the appropriate 5-offset configuration.
