| 摘要 |
<p>A valve stem protection arrangement comprises a hollow square section cap (180) which sits on a valve bonnet and is intended to protect valves from severe operational overload. The cap comprises: a first portion (182) defining a socket (184) to engage the free end of a valve stem; a second portion (188) defining flats for engagement by a valve operating key; and a necked connecting portion (192). The wall thickness of the connection portion (192) is selected such that the portion (192) will fail by shearing at the same or slightly lower load than the valve capability. The outer surface of the first portion (182) may be shaped for engagement by an operating tool to facilitate removal of this portion following shearing of the connecting portion (192). <IMAGE></p> |
