We have a fabrication shop and I need to run 5 more single phase 230 plug ins for our welders. How do I go about this?

Do you have the amperage capacity for this number of welders? You need to do a load determination vs. wire ampacity and if acceptable, add the additional outlets. Or, you may need a new service for the welders. We know nothing about your welders, Stick, TIG, MIG?? Get the info from the plates on the welders.

Standard plug that comes on many welders is Nema 6-50P, receptacle is 6-50R. As long as you have 8 unused CB spaces in a panel, they will each come from one two pole 50A CB. Your main will trip at this panel if you exceed it's amperage rating though.

Do you have single phase or 3 phase power at the panel? If you have 3 phase do you know if you have a high leg in that panel? What is the main/disconnect amperage rating for that panel? Is the panel fed from a transformer?