Assembly is a very important step to achieve tightness and function of stuffing box stem seals.
During assembly, a good seating of the packing has to be reached, first. This is realized by plastic deformation of the packing rings. Existing gaps (between stem and packing / packing and housing / between the rings) have to be filled and internal leakage paths have to be closed. This process is accelerated with increased load.
After this pre-deformation, a given assembly stress value (tightening torque) has to be applied. Usually, the packing is compressed axially using a gland and bolts; the main tightening surfaces are between stem and packing / packing and housing. Therefore, regarding tightness, a sufficient radial force (better: radial stress) has to be maintained during every state of operation.
However, the preload of the packing rings also increases the frictional force between the stem and the packing material, which impairs the mobility of the stem. In order to minimize the frictional force and maintain the mobility of the stem, the preload of the packing rings should be as low as possible.
Both requirements, on the one hand the high tightness of the connection, on the other hand the low stem frictional force, represent contradictory demands on the amount of preload of the packing rings during assembly.
In order to obtain a tight and functional fitting, care must be taken during assembly to apply sufficient but not too high pretension.
For this task, we have developed a hydraulic clamping device that enables controlled and safe assembly - TEMESstb.ctrl. The system consists of
For all applications in which documentation of the installation packing stress is required, our system TEMESstb.ctrl with a metrological extension offers the possibility of measuring and recording both the bolt force and the deformation of the packing rings.
Controlled Prestressing of Stuffing Box Packings with
AMTEC hydraulic tensioning.