1, the standard flange is a universal part, various specifications of the flange's external diameter, screw hole, the thickness is fixed. Moreover, the standard flange considers safety factors, so the safety margin for size and thickness is relatively large.
2, not standard flange is generally the flange designed by the company or individual in order to save materials or to draw materials from the local area.
In general, non-standard flanges will be designed to be smaller and thinner than national standard flanges to save materials, and can also change the form of dense covers, such as sealing with O-rings.
3, the national standard flange market can buy, non-standard flange must be designed, self-processing.
4, non-standard flange suitable for many occasions, such as a device tube flange working pressure of only 0.3 MPA, you do not need to use 0.6 MPA standard flange, you design your own small and thin non-standard flange, But consider that your own design and manufacturing costs are less than the material costs you save.