1, according to the chemical industry (HG) industry specifications: integral flange (IF), threaded flange (Th), plate flat welding flange (PL), necked butt welding flange (WN), necked flat welding flange (SO), socket welding flange (SW), butt welding ring loose flange (PJ/SE), flat welding ring loose flange (PJ/RJ), lined flange cover (BL(S)), flange cover (BL) [2].

2, according to the petrochemical (SH) industry specifications: threaded flange (PT), butt welding flange (WN), flat welding flange (SO), socket welding flange (SW), loose flange (LJ), flange cover (not table note).

3, according to the machinery (JB) industry specifications: the whole flange, butt welding flange, plate flat welding flange, butt welding ring plate loose flange, flat welding ring plate loose flange, flanged ring plate loose flange, flange cover.

4, according to the national (GB) norms: overall flange, threaded flange, butt welding flange, necked flat welding flange, necked socket welding flange, butt welding ring necked loose flange, plate type flat welding flange, butt welding ring plate type loose flange, flat welding ring plate type loose flange, flanged ring plate type loose flange, flange cover.

Precautions

　　1, the bottoming must use J506 welding rod manual overlay welding, and the use of low current welding. Strictly in accordance with the welding process. 2, after welding a position, are to use the degree ruler card flange plane deformation. 3, while welding with a gas hammer hammering weld to achieve the effect of stress relief.

Four series of reducer flange gasket

　　Gasket is a kind of ring made of material that can produce plastic deformation and has certain strength. Most of the gaskets are cut from non-metallic sheets or manufactured by professional factories according to the rules, and the materials are asbestos rubber sheet, asbestos sheet, teflon sheet, polyethylene sheet, etc.; there are also metal-wrapped gaskets made of thin metal sheets (white iron, stainless steel) wrapped with non-metallic materials such as asbestos; there is also a winding type gasket made of thin steel belt and asbestos belt together, the most common one is stainless steel belt and graphite. The most commonly used metal-wound gaskets are made of stainless steel tape and graphite, and the winding tape can be used with asbestos depending on the application environment. Common rubber gaskets are suitable for places where the temperature is lower than 120℃; asbestos rubber gaskets are suitable for places where the temperature is lower than 450℃ for water vapor, lower than 350℃ for oil and lower than 5MPa for pressure, and for common corrosive media, the most commonly used is acid-resistant asbestos sheet. In high-pressure equipment and pipelines, lenticular or other shaped metal gaskets made of copper, aluminum, No.10 steel, stainless steel are used. The contact width between high pressure gasket and sealing surface is very narrow (line contact), and the processing brightness of sealing surface and gasket is high.

　　Low pressure small diameter has wire connection flange, high pressure and low pressure large diameter are used welding flange, the thickness of flange and articulated bolt diameter and number are different for different pressure.