Designs per the AD-Merkblätter require the use of DIN materials. DIN materials may have different mechanical properties than ASME materials. Even when a DIN material is determined to be “equivalent” to an ASME material, one must be careful in its application. For example, the requirements for MDMT as defined in AD-Merkblatt W 10 are not the same as ASME. This is one reason why you should not mix the two Codes in your design.
If your vessel is installed in Germany, your local TÜV will be involved in the approval of the vessel. Having worked with TÜV in the past, I am confident that TÜV will not allow this deviation.
AD-Merblatt B 3, Domed Ends Subject to Internal or External Pressure, and B 4, Dished Heads, contain very straight forward design information. I don’t think that there is anything in these two sections that deviate significantly from Section VIII, Div. 1.
K. Phan