Dear Paldex
Here concept of connecting node is just to get force & moment calculated data at the output restraint summery.
Say we have a straight pipe node 10 then 20(mid point) after that 30
We can model as
a) 10 to 20 then 20 to 30
b) 10 to 20 ,at 20 connecting node 21 with anchor , then 21 to 30

Above both represent the same thing. Only difference is that for option b at node 20 we will get force & moment data at restraint output summery. Option a also have same force & moment but it will not show in output result.

In your case since you are putting anchor at pump center line , Face of flange just connection so output restraint report will not so force & moment at flange interface.
If you make it with connecting node it will show the same & you can compare it with API pump allowable.

Regards
Habib