Gauging the Force Effects of Valve Stem Packing on Valve Stem Actuation PUBLIC ACCESS

[+] Author Affiliations
James Drago, Wayne Evans

Garlock Sealing Technologies, Palmyra, NY

Paper No. PVS2017-3518, pp. V001T03A004; 15 pages
  • ASME/NRC 2017 13th Pump and Valve Symposium
  • ASME/NRC 2017 13th Pump and Valve Symposium
  • Silver Spring, Maryland, USA, July 17–18, 2017
  • Conference Sponsors: ASME
  • ISBN: 978-0-7918-4070-2
  • Compilation Copyright © 2017 ASME


Stem friction in an operating valve is a function of the dynamic interaction of a number of variables — packing material of construction, number of packing rings, compressive load, lubrication, stem surface finish, temperature, cycling, etc. Forces due to friction can be reduced by modifying these factors. Attaining low actuation force and good sealing requires a balanced approach. Packing manufacturers have their own procedures for determining the frictional properties of different packing materials. This paper will show one such procedure and how varying materials and packing set configurations affect actuation force. The focus will be on linear reciprocating valve stems.

The equation F = π × d × H × GS × μ × Y can be used to calculate the force of the packing on the valve stem: Where F - Force needed to overcome packing friction; d - Stem diameter; H - Packing set height; GS - Compressive stress on the packing; μ - Packing coefficient of friction; Y - Ratio of radial to axial load transference, commonly equal to 0.50. Knowing the force, F, by test allows the calculation of the packing set’s frictional characteristics. . This knowledge can guide valve designers and builders to properly size actuating units for consistent and reliable valve performance.

Paper published with permission.

Compilation Copyright © 2017 ASME
This article is only available in the PDF format.



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