Flange is the component linking the pipes and interconnecting the valves, it connects the pipes ends. The flange has holes, two flanges are bolted tightly. The gasket seal is used between the flanges. The flanges are divided into threaded connection (screwed) flange, welded flange and the flange with sleeve. 

The flange is a component interconnecting between the pipes, it is used for the connection between the pipes ends; It is slso used at the inlet and outlet of the equipment for connecting the two devices, such as the reducer flange. Flange connection or flange joint, which means that the flang, gasket and bolts are mutually connected as a set of  detachable connection of compound sealing structure. Pipe flange refers to the flange for plumbing in piping installation, the flange used at the equipment refers to the inlet and outlet flange of the equipment. The flange has holes, two flanges are bolted tightly. The gasket seal is used between the flanges. The flanges are divided into threaded connection (screwed) flange, welded flange and the flange with clamp. Flanges are used in pairs,the threaded connection flanges are used at low pressure pipe and the welded flanges are used at the pipes with pressure more than 4 kg. The gasket is provided between two slices of flange and the slices of flange are bolted tightly. The thickness of the flanges with different pressure is different, the bolts used for them are different also. As for the water pump and valve, when they are connected with the pipe, the local part of these equipment is also made into the corresponding flange shape, which is also known as flange connection. All the connecting parts that are bolted and sealed around the two surfaces are generally referred to as the "flange", such as ventilation pipe connections, this kind of parts can be called "flange parts". But this connection is only a part of the equipment, such as the connection of flange and water pump, the water pump can be called ""Flange -type parts ". The smaller size part,  such as the valve, it can be called "Flange -type part".