If the sheathing is so closed as to be gas-tight (e.g. in the case of vacuum-insulation), a device shall be provided to prevent any dangerous pressure from developing in the insulating layer in the event of inadequate gas-tightness of the pressure receptacle or its fittings.
如果包层很紧密因而是不透气的(例如真空隔热的情况)，必须配备一个装置以防止在压力贮器或其配件不够气密时隔热层内产生危险的压力。