I suspect it has probably been done at one time or another, but I suspect for buried crossings rarely beyond e.g. individual flanges used for discrete connections only. One reason for this is that casings are often not perfectly straight, whereas fabricators at least intend that flange piping is so (maybe not a good combination?)
As to how large casing would have to be, that will be dependent on pipe size, flange design and appropriate clearances (that are easily searched, and maybe another reason flanges are rarely used in such installations?)