| 摘要 |
<p>A valve with fire-resistant seal for use in industrial piping applications. The valve includes a valve body with a valve element therein. The valve is illustrated as a ball valve, but other valve configurations could also be used. A valve stem engages the valve element so that it can be rotated between open and closed positions. A conventional primary seal is used on the valve stem for normal conditions. The valve body defines a body bearing surface, and the valve stem defines a facing stem bearing surface. A thrust bearing is disposed between the body and stem bearing surfaces, and a fire-resistant seal is positioned radially inwardly from the thrust bearing. Initially, the fire-resistant seal is not engaged with at least one of the body or stem bearing surfaces, and the fire-resistant seal has a thickness less than an initial thickness of the thrust bearing. If the valve is subjected to heat such that the thrust bearing is destroyed or damaged, pressure loading on the valve stem forces the fire-resistant seal into sealing engagement between the body and valve stem. At least a portion of the fire-resistant seal is forced into a cavity defined in the body by a chamfered surface.</p> |
