A hot blast control valve for a metallurgical installation, in particular for controlling the flow of hot blast of a blast furnace, said hot blast control valve comprising: a metallic valve housing with a refractory lining in which a gas channel is defined; a valve member rotatably arranged in said gas channel so as to be able of varying a free passage in said gas channel by rotation of said valve member about a rotation axis between an open position and a closed position; said valve member having an envelope with rotational symmetry about said rotation axis; a through passage arranged in said valve member in a direction transversely to said rotation axis of said valve member; wherein said through passage has a cross-section substantially identical to that of said gas channel; and wherein said through passage is arranged in said valve member so as to be aligned with said gas channel when said valve member is in its open position characterised in that said valve member comprises - a cylindrical body portion with a first base and a second base opposite said first base; said first base being provided with connection means for connecting said valve member to a shaft; said cylindrical body portion having a diameter larger than the diameter of said gas channel; and - a hemispherical body portion with a base arranged on said second base of said cylindrical body portion wherein said through passage is arranged to pass through said cylindrical body portion and said hemispherical body portion of said valve member. a metallic valve housing with a refractory lining in which a gas channel is defined; a valve member rotatably arranged in said gas channel so as to be able of varying a free passage in said gas channel by rotation of said valve member about a rotation axis between an open position and a closed position; said valve member having an envelope with rotational symmetry about said rotation axis; a through passage arranged in said valve member in a direction transversely to said rotation axis of said valve member; wherein said through passage has a cross-section substantially identical to that of said gas channel; and wherein said through passage is arranged in said valve member so as to be aligned with said gas channel when said valve member is in its open position characterised in that said valve member comprises - a cylindrical body portion with a first base and a second base opposite said first base; said first base being provided with connection means for connecting said valve member to a shaft; said cylindrical body portion having a diameter larger than the diameter of said gas channel; and - a hemispherical body portion with a base arranged on said second base of said cylindrical body portion - a cylindrical body portion with a first base and a second base opposite said first base; said first base being provided with connection means for connecting said valve member to a shaft; said cylindrical body portion having a diameter larger than the diameter of said gas channel; and - a hemispherical body portion with a base arranged on said second base of said cylindrical body portion wherein said through passage is arranged to pass through said cylindrical body portion and said hemispherical body portion of said valve member.