Investigation of the Service Behaviour and Assurance of the Long Term Performance of Stuffing Box Packings

Project Number 222

The stuffing box sealing element is an important part in view of the proper function of valves. It has to fulfil mainly two requirements: on one the hand it has to guarantee the opening and closing function of the valve (movability of the stem), on the other it has to assure the required tightness for the given service conditions.

Main objective of the research project is the investigation of the service behaviour and assurance of the long term performance of stuffing box packings especially with respect to the relevant service conditions. This shall result in a reliable service behaviour of stuffing box sealing elements in valves on the basis of suitable design in view of long term service, optimized construction and mounting method as well as maintenance. The well founded physical description of the relaxation, oxidation and tightening behaviour of packing materials will allow long term prediction.

The objective shall be reached with the following working programme. Main part is the determination of the properties and factors of the packing materials relevant to design of stuffing box sealing element under the influence of service conditions, especially in view of the long term behaviour:

  • deformability and compressibility,
  • elastic resilience,
  • conversion factor (conversion of axial stress into radial stress in the packing),
  • friction coefficient (between stem and packing),
  • leakage rate and minimum required compression stress for required tightness, and
  • creep and relaxation behaviour.

These investigations are carried out with specially developed or modified test rigs for

  • compression tests,
  • friction tests,
  • leak rate tests, and
  • relaxation tests.

The project is sponsored by Arbeitsgemeinschaft industrieller Forschungsvereinigungen (AiF). It will be carried out from April 1, 2002 to March 31, 2004 at MPA Stuttgart (person in charge: Dr. Hans Kockelmann) and supervised by a working group of the VGB-Working Panel "Pipe Systems, Valves and Pressure Vessels".