This is how Large Flange are made…

Flanges are used for connecting pipes, valves, pumps and other equipment to form a piping system. We see then day to day for the piping system, but when it comes to huge pipelines like petroleum or huge manufacturing industries very large size of flanges are required. Flanges are usually welded or screwed. Flanged joints are made by bolting together two flanges with a gasket between them to provide a seal.