This could compromise the power and integrity on the joint. To avoid porosity, eliminate the zinc coating while in the weld place. Compression fittings give you a rapid and hassle-free Alternative for connecting galvanized pipe with out threads. They consist of a system, nut, and ferrule. To utilize compression fittings: https://www.malleableiron-pipefitting.com/industry-knowledge/how-to-connect-non-threaded-galvanized-pipes.html