National standard flange (English: National standard flange) refers to the flange sheet produced according to the national standard of the People's Republic of China "GB/T 9112~9124-2010 Steel Pipe Flange".
The national standard flange standard was jointly promulgated by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on 2011-01-10 and the National Standardization Administration of the People’s Republic of China.
GB/T 9112~9124-2010 includes the following 13 standards:
Replace the national standard GB/T9112-2000; GB/T10745-1989 standard
GB/T 9112-2010 Steel pipe flange types and parameters
GB/T 9113-2010 Integral steel pipe flange
GB/T 9114-2010 threaded steel pipe flange with neck
GB/T 9115-2010 Butt welding steel pipe flange
GB/T 9116-2010 Flat welded steel pipe flange with neck
GB/T 9117-2010 Socket welded steel pipe flange with neck
GB/T 9118-2010 Butt welded ring loose sleeve steel pipe flange with neck
GB/T 9119-2010 Plate flat welded steel pipe flanges
GB/T 9120-2010 Butt welded ring plate loose steel pipe flange
GB/T 9121-2010 Flat welded ring plate loose steel pipe flange
GB/T 9122-2010 Flanged ring plate loose steel pipe flange
GB/T 9123-2010 steel pipe flange cover
GB/T 9124-2010 steel pipe flange
Technical conditions
The pressure mark specified in this standard is divided into PN mark and Class mark.
PN marking has 12 pressure levels
They are: PN2.5; PN6; PN10; PN16; PN25; PN40; PN63; PN100; PN160; PN250; PN320; PN400
Class marked with 6 pressure levels
They are: Class 150; Class 300; Class 600; Class 900; Class 1500; Class 2500
Another meaning of the national standard flange is: the flange plate produced in accordance with the size and tolerance range required by the national standard, which is different from the flange plate produced not according to the standard size, is also called the second standard flange (someone called the non-standard flange Is incorrect), usually some unscrupulous merchants will reduce the flange thickness and outer diameter to save materials, and use waste steel or scrap steel to process flanges, usually this steel is chemical composition and mechanical For scraps with substandard performance, some even use private steelmaking in black steel plants to produce flanges. The old steelmaking technology used in this private steelmaking cannot guarantee mechanical properties and welding performance, and may not be able to be welded to steel pipes during use, or If the steel itself has cracks, pores, etc., water will leak after being welded, so try to use national standard flanges when buying flanges. If you have limited funds to choose the second standard flange, you must carefully observe and measure the flange size to avoid being fooled.
Processing professional equipment
Processing and manufacturing large-diameter flanges requires professional equipment to achieve twice the result with half the effort. Professional equipment includes CNC disc milling machines, large-head lathes, etc.
