Flange, also known as a flange boss or rim, is a component that connects shafts to each other, used for pipe end connections; it is also used on equipment进出口 for connecting two devices, such as reducer flanges. A flange connection or flange joint refers to a removable joint that consists of a flange, gasket, and bolts, working together as a combined sealing structure. Pipe flanges are those used in piping installations, and when used on equipment, they refer to the equipment's inlet and outlet flanges. Flanges have holes and bolts are used to tightly connect the two flanges. Gaskets are used to seal the flanges. Flanges come in threaded (screwed) connections, welded flanges, and clamp flanges. Flanges are always used in pairs; low-pressure pipelines can use threaded flanges, while those above four kilograms of pressure use焊接 flanges. Two flange discs are fitted with a sealing gasket and then secured with bolts. Flanges of different pressures have different thicknesses and require different bolts. In the connection of equipment like pumps and valves to pipelines, these components are also made in corresponding flange shapes, also known as flange connections. Any connection that uses bolts to join two flat surfaces and seal them is generally called a "flange," such as the connection of ventilation pipes, which can be referred to as "flange-like components." However, such connections are only a part of a device, like the connection between a flange and a pump, so it's not appropriate to call the pump "flange-like components." Smaller components like valves can be referred to as "flange-like components."