Assist the Pipe Assistance the pipe higher than and underneath with riser clamps so it can not drop or sway as you're employed, and Therefore the PVC fitting will not should bear the load of the drain. You almost certainly will require to put in a new stud or two https://www.malleableiron-pipefitting.com/industry-knowledge/how-to-connect-non-threaded-galvanized-pipes.html