A method of completing a well includes lowering a wellhead onto a base at an upper end of the well. A hub with internal threads and an external circumferential stepped recess is secured to external threads of the wellhead. A blowout preventer assembly with an annular locking member having a plurality of locking elements is landed on the hub, and the locking elements are engaged with the recess of the hub. The well is drilled through the blowout preventer assembly to a greater depth then the blowout preventer assembly and the hub are removed. A threaded flange with a plurality of bolt holes spaced around the flange is secured to the external threads of the wellhead and a wellhead member is bolted to the bolt holes of the threaded flange.