Flat welding flange flange body made of metal material is mainly at the end of the flanged fittings and flanges, the main production process of casting, medium plate rolling, forging, cutting the plate is made of various methods, such as craft flat welding flange process flange quality is not the same. Flat welding flange in China mostly according to the requirements of national standards for size, tolerance range, such as the production of flange, if inferior most of flat welding flange is usually obsolete technology or steel itself has cracks appear porosity could leak after welding up, such as on the industry of flat welding flange not according to the standard size production of flange has called two standard flange.

Flat welding flange technical conditions

Check the pressure of the provisions of this standard is divided into the PN mark and Class tag.

PN tag has 12 classes

Respectively: PN2.5; PN6; PN10; PN16. PN25; PN40; PN63; PN100; PN160; PN250; PN320; PN400

Class tag has six classes

The size of the flat welding flange according to the national standards, tolerance range, such as the production of flange, apart from not according to the standard size production of flange piece also said two standard flange (someone called non-standard flange is not correct), usually some unscrupulous merchants will reduce two flange thickness, diameter size to achieve the purpose of saving material, and made from scrap steel and scrap steel flange, is usually the steel chemical composition and mechanical properties of substandard waste, moreover steelmaking production flange with black steel private, the private steel steelmaking technology using old, there is no guarantee that the mechanical properties and welding performance, use which may not be able to and steel pipe welding, such as cracks, porosity or steel itself will leak after welding.