Dry Gas Seals The main form of failure
Several types of dry gas seals
Ordinary corrugated pipe dry gas seal failure form The current use of bellows dry gas seal and auxiliary system caused by the failure of the main form of failure are the following.
1, bellows failure or fracture caused by sealing failure. Bellows in the use of the process, the stiffness of the fire pump dry gas seal or elasticity will gradually reduce the phenomenon of this elasticity is often called the loss of the bomb. Experimental and practical applications show that when the amount of loss of bellows exceeds the initial compression of 18% to 20%, the entire bellows dry gas seal will leak. Metal bellows machine sealed at a temperature below 200 ℃ when the phenomenon is not obvious, but at high temperatures (more than 300 ℃) to use, after driving the pump will soon leak, will use the machine to remove the measured resistance Chi dry gas Seal the metal bellows assembly height found to be lower than the average 2 ~ 3mm before installation. Corrugated tube loss is mainly due to permanent deformation or stress multi-stage pump dry gas seal relaxation, there is a situation is the working medium crystallization precipitation or solidification in the corrugated pipe gap, the bellows deformation ability to reduce or loss of deformation capacity. Therefore, the high temperature and load is the main cause of the loss of the bellows. In addition, the high temperature and bellows compression or contact pressure is larger, the bellows will break; the higher the temperature, the greater the load, the higher the probability of occurrence of rupture of the bellows.
2, the pair of friction on the graphite ring in the excessive wear caused by the seal failure. Typically, the failure of the machine seal removed inspection found that graphite seal ring wear serious. Through analysis and experiment, it is found that the end face of the metal bellows is affected by the effective diameter of the bellows, and the effective diameter changes with the change of the pressure. Due to excessive pressure, resulting in serious friction friction, graphite ring caused by excessive wear and tear.
3, the pair of friction on the surface of the carbide ring hot cracking caused by the seal failure. It has been found that the cemented carbide rings of the sealing friction pairs appear to have many radial cracks, which are divergent from the center of the hard surface, which is a seal failure caused by thermal cracking. The main reason for the thermal cracking is the high local thermal stress. The difference of the linear expansion coefficient between the cemented carbide ring and the ring is different, and the type of the flushing liquid in the flushing system is sealed by the surfacing structure or the whole structure. The size of the flow and the size of the flow may be caused by the sealing surface of the hot crack.