To connect unthreaded galvanized piping, you will have to use a coupling to put The 2 pipes with each other. After you have picked the proper coupling, you will have to use fastening bolts and a torque wrench to help keep the two pipes coupled. Making sure that you can https://www.malleableiron-pipefitting.com/industry-knowledge/how-to-connect-non-threaded-galvanized-pipes.html