Depends on if that specific local has "rig" agreements.  If a job is a food plant or "short" or under 7 miles the jurisdiction usually falls to the local in that area, if it's a long line agreement it belongs to 798 out of OK.  But in areas in CA and WA I have seen UA welder use their rigs on plant maintenance work as well as pump stations and short pipelines.  But a lot of locals don't have rig agreements and the work for a rig welder is pretty scarce.