A riser-component assembly having a primary lumen (104a, 204a), the assembly comprising: a first flange (108, 208, 408) comprising: - a first mating face (108b, 208b) configured to mate with a flange of a first adjacent riser segment, and - a first central flange lumen (108a, 208a) in fluid communication with the primary lumen (104a, 204a); - a housing (116, 216, 416) permanently coupled to the first flange (108, 208, 408), the housing (116, 216, 416) having a first opening (116a, 216a), a second opening (116b, 216b), and a central chamber (116c, 216c) in fluid communication with the primary lumen (104a, 204a) and configured to receive an annular seal (124, 224) around a primary axis (104, 204) extending through the first and second openings (116a, 216a, 116b, 216b) such that the annular seal (124, 224) can selectively seal an annulus in the housing (116, 216, 416)around a drill string extending through the first and second openings (116a, 216a, 116b, 216b); a second flange (112, 212, 412) comprising: - a second mating face (112b,212b) configured to mate with a flange of a second adjacent riser segment, and - a second central flange lumen (112a, 212a) in fluid communication with the primary lumen (104a, 204a); and wherein the assembly further comprises a flow diverter permanently coupled to the second flange (112, 212, 412) between the housing (116, 216, 416) and the second flange (112, 212, 412), the flow diverter having a collar (128, 228) defining a lateral opening (120a, 220a) in fluid communication with the primary lumen (104a, 204a), the collar (128, 228) having a collar lumen in fluid communication with the primary lumen (104a, 204a), a main tube (132, 232) having a main tube lumen in fluid communication with the primary lumen (104a, 204a), and a valve (136, 236, 436) in fluid communication with the lateral opening (120a, 220a), the valve (136, 236, 436) having a longitudinal flow axis (136a, 236a) that is more parallel than perpendicular to a longitudinal axis extending through the first and second central flange lumens (108a, 208a, 112a, 212a) of respective first and second flanges (108, 208, 408, 112, 212, 412) characterized in that the flow diverter and housing (116, 216, 416) are permanently coupled together. a first flange (108, 208, 408) comprising: - a first mating face (108b, 208b) configured to mate with a flange of a first adjacent riser segment, and - a first central flange lumen (108a, 208a) in fluid communication with the primary lumen (104a, 204a); - a housing (116, 216, 416) permanently coupled to the first flange (108, 208, 408), the housing (116, 216, 416) having a first opening (116a, 216a), a second opening (116b, 216b), and a central chamber (116c, 216c) in fluid communication with the primary lumen (104a, 204a) and configured to receive an annular seal (124, 224) around a primary axis (104, 204) extending through the first and second openings (116a, 216a, 116b, 216b) such that the annular seal (124, 224) can selectively seal an annulus in the housing (116, 216, 416)around a drill string extending through the first and second openings (116a, 216a, 116b, 216b); - a first mating face (108b, 208b) configured to mate with a flange of a first adjacent riser segment, and - a first central flange lumen (108a, 208a) in fluid communication with the primary lumen (104a, 204a); - a housing (116, 216, 416) permanently coupled to the first flange (108, 208, 408), the housing (116, 216, 416) having a first opening (116a, 216a), a second opening (116b, 216b), and a central chamber (116c, 216c) in fluid communication with the primary lumen (104a, 204a) and configured to receive an annular seal (124, 224) around a primary axis (104, 204) extending through the first and second openings (116a, 216a, 116b, 216b) such that the annular seal (124, 224) can selectively seal an annulus in the housing (116, 216, 416)around a drill string extending through the first and second openings (116a, 216a, 116b, 216b); a second flange (112, 212, 412) comprising: - a second mating face (112b,212b) configured to mate with a flange of a second adjacent riser segment, and - a second central flange lumen (112a, 212a) in fluid communication with the primary lumen (104a, 204a); and - a second mating face (112b,212b) configured to mate with a flange of a second adjacent riser segment, and - a second central flange lumen (112a, 212a) in fluid communication with the primary lumen (104a, 204a); and wherein the assembly further comprises a flow diverter permanently coupled to the second flange (112, 212, 412) between the housing (116, 216, 416) and the second flange (112, 212, 412), the flow diverter having a collar (128, 228) defining a lateral opening (120a, 220a) in fluid communication with the primary lumen (104a, 204a), the collar (128, 228) having a collar lumen in fluid communication with the primary lumen (104a, 204a), a main tube (132, 232) having a main tube lumen in fluid communication with the primary lumen (104a, 204a), and a valve (136, 236, 436) in fluid communication with the lateral opening (120a, 220a), the valve (136, 236, 436) having a longitudinal flow axis (136a, 236a) that is more parallel than perpendicular to a longitudinal axis extending through the first and second central flange lumens (108a, 208a, 112a, 212a) of respective first and second flanges (108, 208, 408, 112, 212, 412) characterized in that the flow diverter and housing (116, 216, 416) are permanently coupled together.