Patent attributes
Provided is a seal that can ensure a satisfactory sealing property and can be easily separated from a sealing surface even in the case in which the seal is used for a long period of time under the conditions of a high temperature and a high pressure. The seal includes a seal body mounted in a seal groove that is formed in a first member and a second member is made to be in pressure contact with the first member to form a sealing part. The sealing part that comes into contact with the second member at the entire surface of the sealing part is formed along the entire circumference of the outer peripheral surface of the seal. A step portion is formed on the outer peripheral surface of the seal in such a manner that an area of a contact surface is smaller for the sealing part as the contact area is closer to the bottom side of the seal groove.