well bore the thin walled central pipe 24 is typically not able to withstand the pressures involved rather than making the wall thickness of the relatively large bore drilling riser thick enough to withstand the pressure the flow is diverted to a choke line 26 it is more economic to have a relatively thick wall in a small pipe to withstand the higher pressures than to have the proportionately thick wall in the larger riser pipe when higher pressures are to be contained one of the annular or ram blowout preventers are closed around the drill pipe and the flow coming up the annular area around the drill pipe is diverted out through choke valve 54 into the pipe 52 the flow passes up through c amp k connector 50 up pipe 26 which is attached to the outer diameter of the riser 24 through choking means illustrated at 74 and back into the mud tanks 64 on the opposite side of the drilling riser 24 is shown a cable or hose 28 coming across a sheave 80 from a reel 82 on the vessel 84 the cable 28 is shown characteristically entering the top of the lower marine riser package 32 these cables typically carry hydraulic electrical multiplex electrical or fiber optic signals typically there are at least two of these systems which are characteristically painted yellow and blue as the cables or.