Mechanical Seal Design Research Articles

A Study of Factors Affecting Mechanical Seal Performance

Extensive controlled running of a typical commercial, mechanical seal design, and some variants, was carried out on test rigs to investigate premature random failures in process plant. Computer analyses and topological studies were carried out in support of the test running. It was found that apparently minor variations in seal carbon materials have a disproportionate effect on performance, and can cause catastrophic failure. The detailed results of this study are presented.

Application of mechanical seals to slurries with particular reference to pumps and agitators on flue gas desulphurization plants

Pumps in flue gas desulphurization plants require reliable seals in order to attain the necessary trouble-free working periods. This paper reviews and describes those systems which have been used to date. The general requirement of developing seals which allow a more profitable operation at a reduced investment, without impairing their service life, has led to the design of simple mechanical seals lubricated by the medium itself. This concept is described, together with the results of comprehensive trial runs at the manufacturers' works.

Design and analysis of mechanical face seals

An analytical study of the characteristics of mechanical face seals with misalignment is presented. The complete pressure equation was solved without using the narrow bearing assumption. Results are presented and it is concluded that simplified treatments overestimate the load and the moments particularly at touch. Design charts are given to calculate the separating force, the leakage rate, the moment and coefficient of friction for different tilt parameters ϵ and the ratio r i r o of the inner radius to the outer radius.

A Methodology for Design and Application of Mechanical Seals

This study presents a comprehensive methodology for evaluating seal designs or applications. Three dimensionless parameters were formed from basic mechanical seal theory. These parameters were the stability factor, liquid design factor and the strength design factor. The dimensionless numbers were correlated to maintenance data for mechanical seals in a large refinery. The maintenance data represents over 130 pump years of service. Included in the data were seal lives up to 10 years and shaft speeds up to 7200 rpm. The maximum pressure in the data was 2.4 MPa and the maximum temperature was 200°C. The sealed liquids were various hydrocarbons and water. Because of the relatively uncontrolled base, the data were scattered; however, seal life showed a stronger relationship to the dimensionless parameters than to the pressure-velocity product currently in use for evaluating designs. Presented at the 34th Annual Meeting in St. Louis, Missouri, April 30–May 3, 1979

Factors affecting mechanical seal design and application

Factors affecting mechanical seal design and application

A Hydrodynamic Theory of Radial-Face Mechanical Seals

The existence of a lubricating fluid film between the faces of a mechanical seal has been amply demonstrated, but the mechanisms of lubrication and sealing have yet to be convincingly established. Experimental evidence to show that mechanical seal faces are most probably lubricated by a hydrodynamic action induced by the waviness of one of the surfaces has recently been published by the authors. Following this work a modified form of the narrow bearing approximation to Reynolds' equation for hydrodynamic lubrication has been applied to an idealized wavy faced seal. The resulting theory of seal face lubrication has been extended to include radial flows in the fluid film and predicts a net inward flow of fluid which may be utilized to oppose the flow due to the sealed fluid pressure. Predicted lubrication and sealing characteristics are in substantial agreement with measured values. It is suggested that the performance of mechanical seals can be improved by giving one face an appropriately wavy surface at the time of manufacture; a number of other observations on mechanical seal design are also made.

A theory of sealing with radial face seals

It is now well established that, for reliable operation over a long period, a radial-face mechanical seal must operate with its faces separated by a film of fluid. A comprehensive theory, based on the principles of hydrodynamic lubrication, of sealing under these conditions is presented. A number of observations pertinent to the design of mechanical seals arising from the theory are given, and it is concluded that the hydrodynamic theory can be applied to the design of mechanical seals for considerably more severe duties than those for which they are used at present.