Urea is 46% N.

Not necessarily. It is cut with water at the manufacturing plant. The
stuff that goes to feedlots is usually 70%...
sometimes 50%. The higher concentrations "salt out" faster and solidify.
IIRCC 70% salts out at + or - 134 deg. F.
it is hauled in insulated trailers, usually with a steam coil inside like
asphalt trailer have. The trailers are
usually stainless.

Ah... dry vs. liquid... I don't know of any liquid Urea used here in WI.
There may be some TMR plants that use it for dairy rations, but as far as
farming, it's all 46% dry prilled product. That 70% liquid stuff must be
like slime! We use a lot of 34-0-0 liquid N, and it's slippery as egg
whites.... can't imagine 70% !

Jim