Only Used Wet Wipes – Past Prayers Valid or Not?

As salām ʿalaikum wa raḥmatullāhī wa barakātuhu

In the Name of Allāh, the Most Gracious, the Most Merciful.

In principle, if after urinating or defecating, impurities remain on the orifice, then it is an emphasised sunnah to clean the impurity. If, however, the impurities extend beyond the orifice and come into contact with other parts of the body including the area directly around the orifice, and the area affected is 5.94cm2 then washing becomes obligatory.

Hence, if your practice was to not wash after urinating, however, you are sure that urine was not dripping on to your body or clothes to the extent mentioned above then ṣalāh performed would be valid. On the other hand, if you are sure that urine would have come into contact with the body as mentioned above then those ṣalāh will need to be repeated.

And Allāh Taʿālā knows best.