If you need support measuring the centerline radius of the existing elbow, it is best to speak to an elbow manufacturing expert to make sure you get the proper measurements and the ideal solution for your requirements. Pipe fitter teaching, metal fitter coaching, piping and structural fitter fabricator education tips https://www.malleableiron-pipefitting.com/industry-knowledge/how-to-find-elbow-center-of-pipe.html