Because of this difficulty in closing, operators commonly use wrenches and other persuaders on the valves. To compound this problem the valves do not withstand this abusive treatment to any great extent.

• 由于关闭困难，操作者一般都在阀门上使用扳手和其它强制性工具。使这个问题复杂化的是阀门不能承受任何程度的虐待。