Abstract: An Oil Well Head Fire Cap is a self-locking and sealing adapter coupling that, when lowered onto an uncontrolled well head fire, will connect a new well head valve to a burning oil well casing. When the valve is closed, the fire is extinguished by stopping the flow of gushing fuel. The Coned shape of the device will allow it to center itself and, when forced down with a cement anchor block, will compress an inner casing into a tapered sleeve until it reaches the seal material and seats. A plurality of spring-engaged sprags, set in recesses, with upwardly pointed horizontal teeth, will roll back, out of the way, as the coupling is lowered on the outer, or surface, casing. As the anchor block is removed, the coupling is lifted by the downhole pressure. The spring-engaged sprags will bite into the outer casing forcing them to roll out tighter against the outer casing, making a firmer grip or deeper "bite".