Instruction Manual

Instruction Manual
D102137X012
KALREZ System - Rotary-Shaft Valves
May 2011
5
Tightening Procedures
A modified tightening procedure is recommended for live‐loading the KVSP System to help ensure the correct loading
force is used during the life of the packing and to help avoid any overcompression of the packing. This procedure also
creates open space within the spring set that allows dynamic movement of the packing system to compensate for any
volumetric changes that occur during thermal cycling.
Note
The following tightening procedure will change the final loading force to about 1/2 of a fully compressed disc spring.
1. Hand tighten the gland nuts on the Belleville disc springs and measure the uncompressed or free height.
2. Fully compress the Belleville disc springs alternately and evenly to the flat condition. The flat condition will be
evident by a sharp increase in the applied nut torque. Note that there may appear to be space left between the
springs; this is due to friction between the springs. Measure the compressed height.
3. Back off the disc spring deflection by 1/3 or 33% of the difference between (1) the free, uncompressed spring
height and (2) the fully compressed spring height.
4. The KVSP Systems are designed so the components move together during service to eliminate free space within
the packing system. This is part of the system's design and will occur automatically during service without further
adjustment from normal mechanical and thermal cycling. The resulting working height is then established half way
between (1) the free, uncompressed height and (2) the fully compressed position; this also provides approximately
50% of the load force available from the fully compressed disc spring. This new set position helps give the system an
ideal and balanced load, allowing for expansion and contraction due to temperature variations in the process and
maximizing the service life.
Other Considerations
When retrofitting an existing packing system or repacking a valve with KALREZ packing that has been in service, check
the condition of the packing bore after you have removed the packing. An easy method for cleaning debris and minor
imperfections from the bore is to use a brake cylinder hone attached to an electric drill. This method will do a good job
of cleaning the packing bore without changing the dimension of the bore.
When you have completed this exercise, a good guideline to use in checking the condition of the packing bore is the
20/20 rule. If less than 20% of the surface area of the bore is pitted and if there are no pits deeper than 0.020 inch,
then your packing should work fine. This does not need to be an exact measurement; visual inspection is adequate. If
the packing bore does not meet this criteria, however, you should replace the valve.