A double‑eccentric butterfly valve – also known as a high‑performance butterfly valve or double‑offset butterfly valve – differs from a concentric butterfly valve by two geometric offsets of the rotation axis. First, the shaft is offset behind the seat plane, and second, it is shifted laterally from the pipe centre. This causes the disc to immediately swing out of the seat when opening, rather than rubbing against it. The advantages over concentric valves are reduced seat wear, longer service life and the ability to use metal seats. This makes the double‑eccentric design particularly suitable for higher pressures (PN16 to PN40), elevated temperatures, frequent actuation cycles and media that would damage soft elastomer seats – for example steam, hot gases, abrasive media and aggressive chemicals.