Isolated Opening reinforcement check EN 13445

Greetings all,

In the context of the reinforcement check of an opening for a self reinforced nozzle on a cylindrical drum designed according to EN 13445:

AutoPipe Vessel is calculating the Aps of a self reinforced set on nozzle assuming a=d/2 (opening with no nozzle) instead of a=deb/2 (opening with nozzle). This leads to underestimating the area Aps.

EN 13445 part 3 § says;

"with reference to figures 9.4-7 and 9.4-9 the values useful for compensation of opening shall be calculated as follows: a = deb/2 (...)". 

Figure 9.4-7 corresponds to a set-on nozzle, and indeed in this picture its clear that the thickness of the nozzle shall be considered when computing Aps.

Can someone confirm what it seems to be a bug in the software? Please let me know.

Thanks and stay safe,