What Is a Loose Flange?

The flange cannot be effectively connected with the container or the pipe as a whole. It is considered that the container or the pipe does not share the flange torque with the flange in the calculation.

Loose flange

Right!

National standard flange in English ( National standard flange ) refers to the flange plate produced in accordance with 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 issued by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China and the China National Standardization Administration on 2011-01-10, and it is a recommended standard implemented from 2011-10-01.

GB / T 9112 ~ 9124-2010 includes the following 13 standards:

Replaces 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 steel pipe flanges with neck thread

GB / T 9115-2010 butt-welded 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 welding ring with neck loose tube steel pipe flange

GB / T 9119-2010 flat welded steel pipe flange

GB / T 9120-2010 Butt welding ring plate loose tube steel flange

GB / T 9121-2010 flat welding ring plate loose sleeve steel pipe flange

GB / T 9122-2010 Flange ring plate loose tube 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 with 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 layer of national standard flanges means: flanges produced in accordance with the dimensions and tolerance ranges required by national standards, which are different from flanges that are not produced in standard sizes, also known as two-standard flanges (some people call non-standard flanges) Is incorrect), usually some unscrupulous merchants will reduce the thickness of the flange and the outer diameter of the two dimensions to achieve the purpose of saving materials, and also use waste steel or scrap steel to process the flange, usually this steel is chemical composition and mechanics Wastes with substandard performance, and even flanges produced by private steelmaking in black steel plants. 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 The steel itself has cracks, pores, etc., and will leak after welding. So try to choose the national standard flange when purchasing the flange. If you have limited funds to choose a two-standard flange, you must carefully observe and measure the flange size to avoid being fooled.