SEALING DEVICE AND METHOD OF MOUNTING SAME

A sealing device (10) which seals, by means of a PTFE seal lip (13), the outer periphery of a valve shaft of a butterfly valve used for an EGR system of a vehicle. The sealing device (10) is provided with mounting rings (11, 12) press-fitted in and fixed to a valve shaft insertion hole (102), and also with the seal lip (13) held by the mounting rings (11, 12) and made to be in slidable contact with the outer peripheral surface of the valve shaft. The seal lip (13) is formed in a circular disc shape using a fluororesin, and an inner diameter section (13b) of the seal lip (13) is forcibly deformed by the valve shaft so as to face the flow path (101) side.