According to the national standard requirements of the size, tolerance range and other production of flanges, different from the production of flanges not according to the standard size is also called two standard Flange (some people called non-standard Flange is incorrect) , usually some unscrupulous merchants will reduce the flange thickness, outside diameter two dimensions to achieve the goal of saving materials, there are scrap steel or angle materials processing Flange, usually this steel is the waste material whose chemical composition and mechanical properties are not up to standard. Even more, the Flange is produced by privately-made steel in the black steel works.
The outdated steel-making technology used in this privately-made steel making can not guarantee the mechanical properties and welding properties, may Not be able to use and steel pipe welding, or the steel itself, such as cracks, blowhole welding will leak, so the purchase of flanges try to choose national standard flange. If limited choice of the second standard flange funds must be carefully observed and measured flange size to avoid being deceived.
