Flange is called "flange", its name is directly derived from the English word "flange", and through the transliteration of the way used in Chinese, has become the name we are familiar with now. This name was first proposed by the British in 1809, specifically by an Englishman named Elchardt, and he also proposed the casting method of the flange. Although in the initial period of time, flanges were not widely used, but by the beginning of the 20th century, with the increase of various mechanical equipment and pipeline connection needs, flanges began to be widely used in these fields. There are many kinds of classification flanges, according to the form of flanges classified as follows:
Plate flat welded flange (PL), also known as lap flange, is a relatively simple flange, composed of two pieces of welded steel plate together, usually used for low-pressure pipe connection. The rigidity is poor, so it should not be used for chemical process piping systems with supply and demand, flammable, explosive and high vacuum requirements, and highly hazardous occasions.
Neck flat welded flange (SO) is one of the manifestations of the national standard flange (also known as GB flange), and is one of the commonly used flanges on equipment or pipelines. The lower neck height improves the stiffness and bearing capacity of the flange. Compared with butt welding flange, welding workload is large, welding rod consumption is high, can not withstand high temperature and high pressure and repeated bending and temperature fluctuations.
With neck butt welded flange (WN) is composed of two butt welded steel plates or forgings, which is large, heavy, expensive, difficult to install and locate, and easier to bump during transportation. It is usually used for the connection of medium and high pressure pipelines.
Threaded flange (Th). The inner hole of the flange is processed into pipe thread, and the pipe with thread is connected. It is a non-welded flange, which is suitable for occasions where welding is not allowed on site. Compared with flat welded flange or butt welded flange, threaded flange has the characteristics of easy installation and maintenance. However, when the pipe temperature changes sharply or the temperature is higher than 260 ° C and lower than -45 ° C, it is recommended not to use threaded flanges to avoid leakage.
Ring loose sleeve flange (PJ/PE, etc.) is divided into butt welded ring loose sleeve flange and welded ring loose sleeve flange. It is a movable flange, which is generally matched on the water supply and drainage accessories, and is directly connected with the pipes and equipment in the project with bolts. The purpose of using the butt welded ring loose sleeve flange is generally to save materials, its structure is divided into two parts, the pipe part and the pipe are connected, and the head is made into the butt welded ring. Flanges are made of low-grade materials, and the pipe part is made of the same material as the pipe to achieve the purpose of saving materials.
Use flange is a disk-shaped part, usually used in pairs, mainly used between the pipe and the valve, between the pipe and the pipe and the connection between the pipe and the equipment, play a sealing role. Flange connection or flange joint refers to a detachable connection consisting of flanges, gaskets and bolts connected to each other as a group of sealing structures. Flanges play an important role in the connection of mechanical equipment and pipes, and are interconnected parts between shafts and shafts, used for the connection between pipe ends, and the connection between equipment imports and exports.