anti-explosion packing gland
automatic gland packing
packing gland
充填材料
填密函盖
盘根压盖
孔口封闭器
衬垫压盖
填料压盖
填料函盖
密封衬垫
stern tube packing gland
packing-gland heat exchanger
auxiliary valve relief valve setting
bell- shaped valve cup valve
blade control valve relief valve