Abstract: The holddown and packoff apparatus is disposed on the shoulder of a hanger suspending casing in a well. The shoulder engages a seat in the bore of a wellhead. An expansible metal ring is slideably disposed on the hanger shoulder for engagement with an annular groove in the wellhead. A stop ring is insertable behind the expansible ring to expand and positively hold the expansible ring into holddown engagement in the wellhead groove. An independent sealing assembly is disposed on the stop ring and has one seal for the outer surface of the hanger and another seal for the inner surface of the wellhead. The seals operate in series whereby the sealing engagement of one does not hinder the sealing engagement of the other.

Abstract: A holddown assembly is mounted on a hanger suspending a string of casing or tubing into a well. A shoulder on the hanger engages a seat in the bore of the wellhead and has passages therethrough for connecting the annular spaces above and below the seat. The holddown assembly includes a rigid, radially expansible locking ring having an upwardly facing tapered surface, and a cam ring having an annular tapered surface for camming cooperation with the locking ring surface. The locking ring is disposed on the hanger shoulder opposite an internal groove in the wellhead. The cam ring threadingly engages the hanger and is releasably attached to the running tool whereby upon rotation of the running tool, the cam ring moves downwardly on the hanger threads and no seals are associated with the holddown assembly. The holddown assembly provides a positive holddown and permits locking the hanger down before, during, or after the cementing operation.

Abstract: Mechanical pipe joints of the pin and bell variety, and methods of forming same, wherein the ends are pre-formed so as to permit a controlled interference fit upon joining and preferably provide a double seal against both internal and external pressure, the joints being particularly adapted for field-grade materials, aluminum members, and internally and externally coated members and being readily disengagable and re-formable without producing galling.