Calculation of Stem Packing drag force on API 6A Gate Valve 1

[Mathew Varghese]

Hello
Can anyone help me on how to find the Stem Packing drag force on an API 6A gate valve.
Also what are the forces to be considered while calculating the torque required to crack open the gate valve.

Since the stem has an ACME thread I already have the formula for calculating the torque required to raise or lower a load.

But I'm still unsure of the factors that constitute the load.

Any help will be much appreciated.

Regards

Mathew Varghese

 

[metengr]

Talk to a reputable valve supplier who has technical support.

 

[ddR17]

Mathew,

Have you found out about the stem packing drag force yet? Would you share your findings, please? I would like to learn too.

Usually, the stem packing drag is insignificant compared with gate/seat drag force, however, I am working a 5"-15K valve and I want to be sure that the value is not overlooked.

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Here is how I calculated it:

(packing coe. of friction) x pi x (stem sealing diameter) x (UV packing length) x (working pressure)

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Just any idea how do I calculate the force between the stem and stem packing on paper. Does it have to be done with FEA or through experiments? Any thoughts are highly appreciated.

Thank you!