Abstract: The valve of the present invention comprises a tubular body (1) the central ortion (6) of which defines a shutoff chamber (7) which is accessible via an inspection trap (15). Within this chamber (7) there is housed a removable annular pre-body (8) provided with two radial boreholes (9, 10) serving for the rotary mounting of the shaft (11) of the butterfly (12). Sealing means which cooperate with the body (1), the pre-body (8) and the butterfly (12) make it possible to assure the upstream/downstream tightness of the valve. The inspection trap (15) is closed by a cap (28) provided with a passage within which there is rotatably mounted a drive shaft (35) which is coupled to the shaft (11). This structure permits greater ease of access to the inner parts of the valve, a decrease in volume and weight, and greater ease in manufacture.