What is the national standard flange
National standard flange English (National standardflange) refers to the flange produced according to the Chinese Republic standard "GB / T 9112~9124-2010 Steel pipe flange. The national standard flange standard was jointly issued by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China and the China Standardization Administration Commission in 2011-01-10, and the recommended standards were implemented from 2011-10-01. Instead of national standard GB / T9112-2000; GB / T10745-1989 standard. National standard flange PN markers has 12 pressure grades of: PN2.5; PN6; PN10; PN16; PN25; PN40; PN63; PN100; PN160; PN320 and PN400 .National standard flangeClass marks six pressure levels of:Class 150; Class 300; Class 600; Class 900; Class 1500; Class 2500. Another meaning of the national standard flange is: the flange produced according to the size and tolerance range required by the standard, Different from the flanges not produced by the standard size of the piece is also called the two-standard flange (someone called the non-standard flange is incorrect), Usually some unscrupulous businesses will reduce the thickness of the flange, outer diameter two dimensions to achieve the purpose of saving materials. There are also used steel or scrap steel processing flange, Usually this steel is a waste product of substandard chemical composition and mechanical properties, Some even use black steel mills to produce flanges, The steelmaking technology used in this private steelmaking is outdated and cannot mechanical and welding properties, May not be welded to the steel pipe when used, Or the steel itself has cracks, pores and other welding up will also leak. So when buying flange dish as far as possible to choose national standard flange. If the fund is limited to choose the second standard flange, we must carefully observe and measure the size of the flange and detect its material so as not to be fooled.
