subject: Stepping into flanges [print this page] Stepping into flanges Stepping into flanges
Flange is a major component for connecting two pipes. Generally speaking, it connects the ends of two pipes through threading or welding. Thus, flanges are classified into two big categories according to attended modes: threaded connection (screwed) flanges and welding flanges. If two pipes are arranged to be connected, a pair of flanges, a gasket and several boltsand nuts are needed to complete the flange joint. At first, put the gasket between two sealing faces. Then, tighten the bolts. When the gasket surface pressure reaches a certain level, it would be deformed to fill the uneven parts of sealing surface to achieve the perfect leak tightness.
Flange joint is a kind of detachable link. In terms of detachable components, they are divided into container and tube flanges. From the perspective of structure types, they are integral, loose and threaded flanges. Especially, flat and butt welding flanges are two general types of the integral flanges. The previous one is applicable for working pressure less than 4Mpa for its inferior stiffness. And the later one is the opposite kind which is commonly applied to working circumstance with high temperature and pressure for its superior stiffness. What else, there are three types of sealing faces: planar sealing surface for low pressure, uneven sealing surface for slightly higher pressure and tongue and groove sealing surface for high pressure and flammable, explosive, toxic media.
As you have recognized, different kinds of flanges hold their own tolerant pressure and media. In fact, the gasket used in the joint determines a lot. Most gaskets are acquired from non-metallic plates. Some are specified with size to be gotten from asbestos rubber sheet, asbestos sheet, polyethylene sheet and so on. For example, the upper temperature for general rubber gasket is 120. Acid-resistant asbestos is widely used for general corrosive media. Referring to high pressure, metal sheet made of copper, aluminum, 10 steel or stainless steel is necessary.
Actually, flange holds its own standard system. They are DIN system, ANSI system and JIS system. The previous two systems both contain the regulations for common pressure levels and sealing face types. And the last system is not widely accepted. Furthermore, the producing of flanges should under the according regulations, such as GB standard, chemical industry standard, mechanical standard and pressure vessels standard.
As the technologies develop, it is certain to develop much more competitive flange types. Hope this article do some help for you on the general knowledge of flanges.
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