Downhole screen with exterior shunts and manifolded shunt connections at tubular joints

An assembly of screens made of connected joints with exterior shunts that span the threaded connections among the joints features manifolds for the shunts adjacent joint threaded ends that are connected with a coupling. A mandrel spans from one joint to the next inside the threaded coupling and is sealed to the respective bases pipes on opposed ends of the coupling. At each end of the mandrel the surrounding base pipe has openings from the manifold where the shunts terminate to define an annular flow path between pairs of manifolds. The shunts can have slanted gravel outlet passages or no gravel openings at all. The shunts can span over screen or blank pipe with an option to mount a shroud over the generally parallel shunts.