I'm going to ask out a girl who had a date to the dance as friends
Why would you just go as a friend?
I want her just as a friend and I have too much of a pride to be in a relationship right now.
Keeping a relationship is always hard and would always require effort, so I understand you very well that you don't want to be in a relationship right now. But that girl that you are taking advantage of maybe asked what by someone else that is really interested with her, and you may be robbing that opportunity for someone else and for that girl to be happy. I would recommend that you find someone else on that dance that also want to be with you as friends.
She won't feel hurt since I will tell clearly what exactly I'm expecting from this.
It's good that you don't have any intention to mislead her in any way. I don't see any harm in asking her out but make sure she's on the same page as you.