BOTTOM PACK-OFF CROSS OVER SEAL
The standard bottom pack - off is type 'PBP1’
The bottom pack - off is installed in the lower flange of the casing head spool and tubing head spool to prevent the lower flange from being exposed to high pressure.
The bottom pack-off type 'PBP1' seals the annulus pressure by injecting packing. The bottom pack - off PBP - 2 is designed to give a positive annular seal with pressure energized oversize O - Rings.
For services at working pressures above 5,000 psi, the 'PP' seal is used.
When the bottom pack - off is used, the casing should be cut 90 mm from the top flange surface of the connecting spool.