Stiffness coefficient

[Miley36]

Hi,

API 650, Appendix-P is not really clear for me : i have a problem with stifness coefficients . I don't know how can i determine them .
and also why API650 consider only radial load FR and moments ML and Mc ? I really need your help

Thank you

 

[jte]

Miley-

Try to get a copy of the series of papers by Manfred Lengsfeld et. al. published at the ASME Pressure Vessel and Piping conferences (~1997 - 2006), or the Journal of Pressure Vessel Technology ~2007. Those may help you in determining stiffness coefficients.

As for Fr, Ml, Mc being the only ones considered? Simple enough. The other three (two shear forces and "torque" on the nozzle) don't really have much impact on the shell, as the shell can handle shear pretty well, but is poor in bending. Some vessel books which get into WRC 107 / 297 / 537(?) calc's can give you some more insight on this aspect.