Dear @Muhhamed Omar

I hope attached file is helpful for you.

Shell and tube heat exchangers in mechanical design is considered as pressure vessel.

Also you can refer to ASME VIII code for more details.

Regards.

Dear Muhammad Umar

These standards are include many attributes for design and manufacturing of pressure vessels or heat exchangers.

I think, the projection is could be limited to a minimum due welding requirement and prevent post weld heat treatment or interactions between welding heat zones for the nozzle with the shell and flange.

Regards.

Dear Alaa Temimy ,

Yes, you are right. I have considered welding.

Thank you for your response.