Pressure vessel Design - Splay out concern

[krithika]

Dear Members,
The existing design for the pressure vessel is an end cap bolted to the body which is not designed to any pressure vessel code. Currently I'm trying to qualify this pressure vessel to PD5500 code. Due to the derated allowables in the code i couldn't go with the bolted arrangement, In order to qualify the existing design i have to triple the number of bolts for which i don't have space.

Not left with much options i decided to go with end cap and threaded lock ring ( Please see attachement-BLOGS). The threads i use in the lock ring is stub acme. Although the thread length and lock ring tensile area are good for 300bar ejection load(internal pressure) as per my calculation, I'm more concerned about the splay out of the lock ring. I did some basic FEA from which the deflection i got was 0.2mm but the stresses are localised and quite high. I'm not sure if i can go ahead with the testing with this fine safety factor margin.

Temperature is 20 deg C, but I am not overly concerned about this at this stage.

Material
Body - 65 ksi
Lock ring - 80ksi
End cap - 80ksi.

 

[Baluncore]

So, what is your question ?

 

[krithika]

My question is will the lock ring splay out during pressure testing? Please let me know if you need any additional info.

 

[Danger]

I have no knowledge of this stuff, but I'm still interested in one aspect of the problem. Your drawing makes it appear as if the bottom of the vessel is also attached via a collar rather than being formed-in. If so, is it already pressure rated or are you designing that too?