Flat head calculations

[Lukas_1990]

Hello,

I need an advise on the topic of flat head (flat end) calculations acc. to EN 13445-3.
I have already calculated the minimum required thickness of the flat end (unpierced - welded directly do shell) with equation - EN 13445-3 10.4-10. Now I am not sure how to calculate the thickness for a situation like in picture below:




There are 6 of nozzles (with flanges). How to calculat properly thickness of flat head like in this situation? Can the thickness of the nozzles (on top of flat head) be calculated as in clause 9.5 or in some other way? How to calculate the MAWP and MATP for flat head in this situation?

Data:
- Outsiede diameter of shell: 950mm
- Nominal thickness of shell: 4 mm
- Diameter of flat head - 1000mm (outside and inside weld with shell)
- Desired thickness of flat head - 4 mm
- Design pressure - 0,1 bar g
- All components made of stainless steel 1.4301
- Diameters of nozzles on top of flat head - 1x 406,4mm, 3x 33,7mm, 2x 60,3

Thank you in advance for your help