Minimum Required Stress on the Mechanical Packing

[farzadinjast]

Dear engineers,

I am going to use graphite packing around a shaft to isolate a cavity from the outside. The shaft should go through the wall of a high pressure cavity (70 PSI). I chose a Klinger 40 package but I can not find any clue in the catalog or their website on the required pre-stress on the package. I have heard that the stress is somewhere between 290 to 580 PSI but not sure. I suppose that the stress must be exerted by a coil spring twisted around the shaft. I appreciate any help on the amount of the pressure to design the spring.

Thank you in advance.

 

[farzadinjast]

any ideas?

 

[nickelkid]

I am not sure what you are doing and not sure how a spring is involved. Typically rope packing in a pump or valve is tightened to suit the application, typically not much, maybe 30% of gland bolt max torque, and cycled/tightened to obtain an acceptable leakage,

If Klinger cannot provide you a seat stress for their product, try a different manufacture.

A better description of the application would facilitate a better response