Reducing Flange, also known as Reducing Flange, there is a certain difference between the size of the inside diameter of the standard Flange.

In engineering, when the standard flange can not be matched with pipe fitting and pipe, the reduced diameter flange should be used instead.

Flange standard of our country has the national standard (GB) and chemical industry standard (HG) two categories, the latest chemical industry in the flange standard HG/T20592 ~ 20635-2009 and adopted by eu EN European tube flange standards (nominal pressure using PN) and the United States represented by the ASME American pipe flange system (nominal pressure using the Class), feature sizes between them in the same nominal size there is also a difference; Moreover, China's pipeline diameter series are also divided into metric series and Inch series, they are also different in the nominal size of the same level; In addition, when there are special technical requirements, such as instrument joints, glass lining flange characteristics are also some special requirements (for it to set up the "Glass lining Reducing Flange" HG/T2140-2009 standard). Therefore, in the engineering, there is an inevitable mixing situation, reducing the flange inner diameter size is the simplest and most effective solution, thus the non-standard reduced diameter flange appeared.