a fitting placed in the blowout preventer stack to provide space between preventers for facilitating stripping operations, to permit attachment of choke and kill lines, and for localizing possible erosion by fluid flow to the spool instead of to the more expensive pieces of equipment.

Related Terms

• Choke Line

1. A pipe attached to the blowout preventer stack out of which kick fluids and mud can be pumped to the choke manifold when a blowout preventer is closed in on a kick. 2. A high-pressure pipe leading from an outlet on the BOP stack to the backpressure choke and associated manifold. During well-control operations, the fluid under...

• Stack

1. a vertical arrangement of blowout prevention equipment. Also called preventer stack. See blowout preventer. 2. the vertical chimney-like installation that is the waste disposal system for unwanted vapor such as flue gases or tail-gas streams....

• Hanger Plug

a device placed or hung in the casing below the blowout preventer stack to form a pressure tight seal. Pressure is then applied to the blowout preventer stack to test it for leaks...

• Closing Unit

the assembly of pumps, valves, lines, accumulators, and other items necessary to open and close the blowout preventer equipment....

• Blowout Preventer Operating And Control System

the assembly of pumps, valves, lines, accumulators, and other items necessary to open and close the blowout preventer equipment. Also called closing unit....