For rigid metal conduit see the new 2002 NEC, 344.42 Couplings and Connectors. Threadless. Threadless couplings and connectors used with rigid metal conduit must be made tight. Where buried in masonry or concrete, they shall be concrete-tight. Where installed in wet locations, they shall be raintight (344.42(B) Running Threads). Running threads cannot be used on rigid metal conduit for connection at couplings.
P.S.: What about the connection at the left? Is that a recognized fitting to be used to comply with rules for EMT? See Section 110.3 (B).