A marine riser having a pressure level rating of twenty ksi or more includes riser tubulars and auxiliary lines that are made of steel having an API grade C110 and C125 and is NACE certified. The riser tubulars and auxiliary lines are not welded, but are assembled via threaded, clamped, stabbed or other mechanical and/or hydraulic connections. Some of the connections may be pre-assembled to reduce assembly time on the drill ship.