Patent ID: 8333237

Claim:
A wellhead assembly for isolating a wellhead during a fracing operation, comprising: a casing head; a tubing head coupled to the casing head and having a tubing head flange, the tubing head rated at a wellhead pressure; a frac mandrel supported by and fitted in the tubing head, an outer surface of the frac mandrel constructed to mate with an inner surface of the tubing head; an upper portion of the frac mandrel extending above the tubing head; and a lower portion of the frac mandrel that ends and seals in the tubing head; a secondary flange operatively coupled to the frac mandrel and fastened to the tubing head flange; the frac mandrel arranged to align with a casing pipe and to receive a load responsive to a fracturing pressure, the fracturing pressure exceeding the wellhead pressure; and the secondary flange arranged to redistribute at least a portion of the load, which was generated responsive to the fracturing pressure, from the frac mandrel to the casing head.