Abstract: A new wellhead housing structure which utilizes identical units of a unique wellhead housing of selected internal diameter and pressure rating. Each wellhead housing utilizes a new flexible bowl ("flexbowl") hanger support ring which may be installed and removed as desired during assembly of the wellhead structure during completion of the well. Each wellhead housing forms an internal circumferential groove to receive the flexible bowl hanger support ring in position to receive and support different kinds and sizes of hangers for casing, protective sleeves, and the like. The flexible bowl support ring is drawn into a contracted position. The contracted support ring will pass through the wellhead housing and is seated by a setting tool. Subsequently, a tubing or casing hanger may be landed upon the support ring and supported by the support ring which serves the same functions as the bowl seat in a conventional wellhead housing. The support ring may be removed by a removal tool.