ISO 9974-4:2016
一般用途液压动力连接器. 带弹性体密封或金属对金属密封的ISO 261螺纹孔口和管堵. 第4部分: 外六角和内六角孔塞的尺寸, 设计, 试验方法及要求
Connections for general use and fluid power - Ports and stud ends with ISO 261 threads with elastomeric or metal-to-metal sealing - Part 4: Dimensions, design, test methods and requirements for external hex and internal hex port plugs