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冶金工业的高炉、热风炉、炼钢炉、钢锭加热炉、焦炉、煤气发生炉等,以及其他工业部门的各种工业炉窑,其管道、阀门和设备的法兰等的密封,习惯采用石棉制品或紫铜等材料。石棉制品用于高温密封,当温度超过300℃时,由于结晶水的挥发粉化而产生泄漏。紫铜垫片价格昂贵,没有弹性,经不起温度的剧变,也不是理想的密封工程材料。目前较理想的高温密封材料是膨胀石墨。石油、化工、橡胶、酿造、轻工、制药等工业中的管道和设备(如反应釜、罐、塔等)法兰的平面密封,要求耐化学腐蚀,而膨胀石墨材料对大多数腐蚀性介质均有良好的耐腐蚀密封性能。铁路内燃机车、汽车和各种内燃发动机的汽缸垫、进排气管垫采用膨胀石墨密封材料,具有比发动机更长的使用寿命。膨胀石墨作为一种发展中的新材料,是由它的优异特性所决定的。
Blast furnaces, hot blast furnaces, steel-making furnaces, ingot furnaces, coke ovens, gas furnaces, etc., as well as various industrial furnaces in other industrial sectors, and the flanges of pipes, valves and equipment in the metallurgical industry are conventionally used Asbestos products or copper and other materials. Asbestos products for high temperature sealing, when the temperature exceeds 300 ℃, due to the volatilization of water crystallization and leakage. Copper gaskets are expensive, non-elastic, can not withstand the dramatic temperature changes, nor is it an ideal sealing engineering material. At present, the ideal high temperature sealing material is expanded graphite. Plane sealing of pipes and equipment such as reaction vessels, tanks, towers, etc. in the petroleum, chemical, rubber, brewing, light industry, pharmaceutical and other industries requires chemical resistance and expansive graphite materials are resistant to most corrosive media Have good corrosion-resistant sealing performance. Railway diesel locomotives, cars and a variety of internal combustion engine cylinder pad, inlet and exhaust pipe pad using expanded graphite sealing material, with a longer life than the engine. Expanded graphite as a developing new material is determined by its excellent properties.