修改件2（包括所有之前的修改件）本规范涵盖了石油基液压油系统中球阀阀座密封和止推垫圈（含二硫化钼的尼龙66）所用的材料。

Amendment 2 (all previous amendments incorporated)This specification covers material used for ball valve seat seals and thrust washers (nylon 66 with molybdenum disulfide) in petroleum-based hydraulic fluid systems.