Flange connections involve securing two pipes, fittings, or equipment to separate flange plates first, then inserting a flange gasket between the two plates and fastening them together with bolts to complete the connection. Some fittings and equipment come with a built-in flange plate, which also falls under flange connections. Flange connections are an essential method in pipeline construction. They are convenient to use and can withstand high pressure. In industrial pipelines and residential settings, where pipe diameters are small and the pressure is low, flange connections are not visible. However, in boiler rooms or production sites, flange connections are ubiquitous on pipes and equipment.

The types of flange connections, categorized by their connection methods, include: flat welding flanges, socket welding flanges, blind flanges, threaded flanges, flange covers, loose fit socket welding flanges with neck, loose fit flat welding flanges, ring groove flanges, and covers, large diameter flat flanges, large diameter high-neck flanges, winged blind flanges, and socket welding flanges with loose fit.