Pay attention to torque requirements: The coupler you use will have a different torque need, so choose Take note of it as you sign up for the pipes and tighten the bolts. To connect threaded galvanized pipe, address each of the threads with pipe dope, or wrap the threads with https://www.malleableiron-pipefitting.com/industry-knowledge/how-to-connect-non-threaded-galvanized-pipes.html