Nozzle Allowable Forces and Moments of Equipment

[Mangooo]

I have a problem with finding the origin of below equation which is indicating nozzle allowable forces and moments of equipment.

Please let me know the referenced code or standard of this equation.

 

[JJPellin]

Where did you get this document? Where did this come from?

Johnny Pellin

 

[Mangooo]

I got this formula from my company's design standard.
and I can not where this formula comes from. which is why I post this thread.