Flanged joints are made by bending the end in the raw duct or fitting to help make a ¼” flange. Below is the code section for the International Mechanical Code for your authorized welded duct connections kinds. In combination with your kitchen extraction program, you could be even be needed https://commercial-kitchen-extrac02344.blogdemls.com/36862953/commercial-kitchen-extract-systems-can-be-fun-for-anyone