reference to WRC 297 Calc

In One of my calc,
The Nozzle thk = Shell wall thickness
and d/t<20, so the nozzle is almost rigid and hence one of the conditions of WRC-297 is not satisfied.
But when I use WRC-297 in C-2, the stiffness values are extrapolated and calculated, which qualifies the nozzle with the allowable loads of the vendor.
Our company does not have FE softwares...

Can the results by C-2 be used to qualify the system ?

VESSEL Dmean(mm.)= 1595.000 VESSEL THK. (mm.)= 55.000
NOZZLE O.D. (mm.)= 589.600 NOZZLE THK. (mm.)= 55.000
AXIAL TRANSLATIONAL STIFFNESS ( N./mm. )= 1846560.
LONGITUDINAL BENDING STIFFNESS (N.m./deg )= 5457731.
CIRCUMFERENTIAL BENDING STIFFNESS (N.m./deg )= 943248.

As seen the stiffness values are almost in the order of 10E+6

Mentors Please comment....

Regards,

You basically have a 60"x24" Tee over 2" thick. You should not expect too much "give" in this connection although the stiffness shown is < the 1E12. default CII stiffness. Klong of 5.5E6 Nm/deg (48.E6 in-lb/deg) seems low for this connection, but I have not been runnig any FEA in a while. I would try at least one alternate method to compare the sitff from WRC-297.