This can compromise the strength and integrity on the joint. To prevent porosity, get rid of the zinc coating within the weld location. Spot a coupling bolt on Every single bolt gap and tighten the coupling bolts using a wrench or socket wrench. Make sure to tighten the bolts evenly. https://www.malleableiron-pipefitting.com/industry-knowledge/how-to-connect-non-threaded-galvanized-pipes.html