... beginning by DOT welded. Depend on excellent compression resilient, it is suitable for sealing spots where the alteration of temperature and ... tower, plain hole and man hole of flange, etc. It has been widely applied in the fields of petrochemical, mechanical ... inner ring. 4)material: Metal ring include SS304, SS316, SS316L, carton steel Nontal ring include graphite strip, Non-asbestos strip, PTFE ...