Torque due to piston effect and spring load

[SubseaEng7]

All,

I am just looking through a document with break out torque calculation for a ball valve and was wondering if anyone out there could explain these calculation:

Torque due to piston effect and torque du to spring load; see attached file for calculations.

http://files.engineering.com/getfil...4c99-a594-5965800ef147&file=calculations1.jpg

I am used to a factor of perhaps 1/1000 for the piston effect; (1/1000)*R*E*u, where R = average sealing radius, E = piston effect and u = seat to ball friction coefficient and (2/1000)*R*E*u for the spring load.

It would be great if any of you clever folks out there could explain all the fancy math for deriving the torques in a layman's term for me

Regards

SubseaEng7

 

[al1979]

SubseaEng7,
Integral mentioned in calculation is giving syntax error. May be you can share the entire calcultion sheet?

Cheers!!!

 

[SubseaEng7]

Al1979,

The attaced file is all there is, but when calculating the integral I godt 4.2.


Regards

SubseaEng7

 

[rocky06]

You can take multiplying factor 2.2
2A=Dc so ans of that integral is 2.2.
Didn't understand why did you calculated ball thrust as its value doesn't included in any formula.
Coefficient of Friction is 0.2 for which material?