The pressure mark specified in this standard is divided into PN mark and Class mark.
PN marked with 12 pressure levels
Respectively: PN2.5; PN6; PN10; PN16; PN25; PN40; PN63; PN100; PN160; PN250; PN320; PN400
Class marked with 6 pressure levels
Respectively: Class 150; Class 300; Class 600; Class 900; Class 1500; Class 2500
Another layer of carbon steel 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 methods) Blue 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 Waste materials with substandard mechanical properties, 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. Therefore, when purchasing flanges, try to use carbon steel flanges.