How to distinguish the forged flange and casing flanges

　　How to distinguish the forged flange and casing flanges? I have the following advice:

　　To see whether the surface is smooth, whether the sand Chamfer flange edge is flat. Flange drilling is rough Seal water line is uniform or not beautiful with a caliper amount of each size is qualified, More difficult to forge than the casting of the heavy of course, to compare the general to know that forging don’t have trachoma and casting will have trachoma .