As stated on many forums when asking for help it behooves you greatly to give a MRE (Minimal Reproducible Example) of your issue - the key being Reproducible as in if I copy/paste what you have posted I can run it to see what you are seeing so that I can more easily help you with YOUR issue. So this would be a win-win for you in that your question will get answered faster. Giving code snippets that do not allow just copy/paste run means whomever might help you will either not help you or will be delayed in helping you.
Now since you have not included an MRE I will have to guess the issue you are actually having appears somewhere else within your code because other than this code looking more complex than it needs to -- it appears (without being able to actually test it) that it would work just fine assuming everything else (that I cannot see) was coded correctly.
This line calls the (I assume button) clicked event and if the rest is coded correctly should work just fine and call the "self.add_pipe" function without incident.
Note personally I would have used a semi-standard prefix of btnAddPipe to indicate this was a button rather than response_ because at a glance yours does not indicate at all that its a normal object like a button and as such could just as well as be anything else.
Now since you have not included an MRE I will have to guess the issue you are actually having appears somewhere else within your code because other than this code looking more complex than it needs to -- it appears (without being able to actually test it) that it would work just fine assuming everything else (that I cannot see) was coded correctly.
This line calls the (I assume button) clicked event and if the rest is coded correctly should work just fine and call the "self.add_pipe" function without incident.
self.response_AddPipe.clicked.connect(self.add_pipe)
Note personally I would have used a semi-standard prefix of btnAddPipe to indicate this was a button rather than response_ because at a glance yours does not indicate at all that its a normal object like a button and as such could just as well as be anything else.