The casing spool has a top bowl to accommodate the casing hanger. The spool also has a bottom bowl with a pack-off seal and a flange or clamp hub for mounting it on top of a casing head or previous spool. Outlets are provided for annular access. Multiple casing spools may be stacked to hang intermediate and production casing strings.

Straight bowl prevents wedge-locking of bowl protectors, casing hangers, and test plugs. Also, Type C-22-EG reduces the number of leak paths, lowers cost, and increases safety