US Patent 7493944 Wellhead isolation tool and method of fracturing a well

A wellhead assembly is provided including a first tubular member, a hanger mounted within the first tubular member and an annular member coupled to the outer surface of the hanger. The assembly also includes a second tubular member mounted to the annular member and surrounding a portion of the hanger. A method is also provided for fracturing a well requiring coupling a tubing mandrel hanger to a casing, the hanger having a central bore, coupling an annular nut on a portion of the outer surface of the hanger, mounting a tubular member having a flange over the hanger and on the flange, and applying fluids though the bore formed though the hanger for fracturing the well.