Thanks Richard.

Just one doubt I have:
Indeed WRC mentions cylinder-cylinder intersections at 90 degrees but it may only be applicable if line of axis of nozzle and vessel coincides at some point.
As per my understanding Radial bending stress & stiffness equations in WRC seems not to include the offset distance of nozzle axis with vessel axis (for Hillside nozzles)while calculating bending stresses. If anyone has some deep insight into the equations of WRC then he/she can comment on this. Can this point be confirmed from WRC group if anyone can contact? I need to be sure if i'm using WRC the way it was intended to be used.

Ofcourse i've other options for stiffness calculations as Nozzle Pro etc and I havn't done any comparison of calculated stiffness from an FEA to WRC so far.

The reason for being in doubt is as Hillside nozzle make an ellipse opening in the vessel and that ellipse having Major and Minor dia. The stiffness calculated will always be for Nozzle dia in WRC i.e approx Minor dia of that ellipse nozzle makes during connection. Hence values of Longitudnal stiffness(Ls) versus Circumferential stiffness(Cs) SHOULD differ from Ls and Cs compared to Radial nozzle attached at the same location.

The more appropriate method which is suggested is to calculate Longitudnal stiffness with Major dia of nozzle and Circumferential Stiffness using Minor dia of nozzle. Assigning these stiffness as User defined to the same nozzle will give a more accurate value (Atleast thats what I understand at this moment).

Any comments/suggestions will highly be appreciated on this type of method. I just want to assure you all that I have no intention to reject WRC or methods utilize all over the world but I need to be sure of what best could I do with the situation I have....and...situation is that my Boiler creates alot of stress at Tee points of Nozzle vessel intersections (3x to 4x Allow.Sy)when I don't use nozzle flexibility and after application of WRC297 all stresses have gone away .

Many regards,
Salz