Different Connection types of flanges

The flange joint is to connect two pipes, fittings or equipment. Each of them is fixed to a flange plate. Then put flange gasket between two flange plates and use bolts to fasten them. Some fittings and equipment have flange plates, which is also belongs to flange joint. Flange joint is an important way of piping installation. It's convenient to operate and can bear great pressure, which is applied to a wide range of industrial pipeline. We can't see the flange joint at home due to its small pipe diameter and low pressure. But if we are in a boiler room or production field, there are many flange connected fittings and equipment. 
According to connection way, flange can be classified into welding plate flange, slip-on neck flange, welding neck flange, socket welding flange, threaded flange, blind flange, butt welding neck ring flange, flat welding ring loose flange, etc.