One piece top seal for a valve

摘要

A centrally apertured unitary one piece top seal for a rotary plug valve includes two distinct portions. The first of these portions has a truncated triangular cross sectional configuration with the second portion being circumferentially disposed about the first and being substantially planar. The top seal has a relief area in the first portion at the interface of the aperture defining sidewall and the bottom of the first portion, and a relief shoulder between the first and second portions. The first portion has a height of at least twice that of the second portion and preferably four times that of the second portion.