Failure Analysis Of The Mechanical Seal System Based On FMECA

Mechanical seal as the axial seal for the rotating machinery is widely used in the petrochemical engineering,medicine,aerospace industry.With the fast development of these areas,requirement at the higher level was needed for the mechanical seal.Mechanical seals have been developed into extreme conditions,for example,as far as temperature concerned,there are high temperature seals and low temperature seals,and when it comes to the size area,there exist large size seals and micro-shape seals.What's more,mechanical seals used in conditions where corrosive and high solid concentration working substances occur have also been developed these years.As the working conditions required,higher reliability for the mechanical seals is needed to ensure its stable performance.As for the industry production so far,even many advanced technologies are adopted in the design and manufacture process,failure cannot be absolutely avoided.More investigations about the seals failure are still required.Pitifully,studies related to mechanical seals failure could hardly be seen at home and abroad.Based on the mechanical seals failure analysis and studies about analysis approach in past years,this thesis is supposed to provide some advice to the mechanical seals design,manufacture,installation,operation and maintenance processes.Based on the understanding for the mechanical seals operation requirement and the investigation of their function mechanism,this paper established a more common function structure division for the mechanical seals system,as well as a new failure analysis model for the subsystem based on the P-diagram.After the P-diagram was detailed studied,FMECA method suitable for the mechanical seal system was developed.The FMECA activities related to the design,manufacture and operation were presented.Function and hardware FMECA about the design and operation were detailed discussed and testified on a real working mechanical seal.Fault tree was established and investigated after the FMECA and FTA compared and post-analysis method confirmed.The analysis method used in this paper is suitable for various types of mechanical seals,and can be used in the design and operation processes.Effect of auxiliary seal rings,plastic elements and seal rings for the mechanical failure should be paid more attention in the actual design and maintenance processes.In order to improve the reliability of the mechanical seal system,redundant system should be distributed felicitously,training about the installation and operation as well as the maintenance should be enhanced and manmade failures should be cut down to a certain degree.