Flat Head with Retaining Ring UG-34(m) 1

[JCrash]

When using a retaining ring (Figure UG-34(m)) to hold in a flat head, I have to maintain a factor of safety of at least 4 against all possible means of failure, per UG-34(d).

One of the listed failure modes is radial deformation (flaring of the end of the vessel). The code doesn't provide any real guidance for a preferred method of calculation. In your opinion, how would you calculate this bellmouthing/flaring/radial deformation for a pressure vessel? And what would my factor of safety be against in this case (deformation, slope, etc)?

general info:
(Section VIII Div 1)
(ID = 54 in)
(P = 1900 psi)
(t = 5.625 in)
(definitely not a thin walled pressure vessel)

 

[JCrash]

Thanks, Fawkes. I'm trying to get my organization to buy a copy. We're pretty unfamiliar with CEN specs here.

Are there any other standards that provide analytical methods that anyone knows of?