Gasket deforms during hydrotest, bolts lose torque and must be retightened after hydrotest. (Pressure/temperature transient or frequent cycling produces similar mechanical action in valve.

• 在水力测试时，垫圈会变形，螺栓松动，因此在水力测试后必须加以紧固。（压力/温度转换或周期循环在阀门上产生相似的机械作用。）