Abstract: A valve body with a retainer shoulder mounted on the side of the valve body. Inside the valve body is a valve obturator means which is rotatable inside the valve body and can open or block passages depending on the angle or position of the valve obturator means inside the valve body. A handle or lever is connected to the valve obturator means by a fastening means. A locking means is slidably mounted on the handle and has a stopping tooth which is positionable adjacent the retainer shoulder when the locking means is in a locked position. The stopping tooth and the retainer shoulder cooperate to block rotation of the handle when the locking means is in the locked position. The handle defines a bore which receives a bolt of a padlock. When the bolt of the padlock is in the bore, the locking means is prevented from moving out of the locked position.