annular preventer การใช้

• Both types of annular preventer are in common use.
• Regulations typically require that an annular preventer be able to completely close a wellbore, but annular preventers are generally not as effective as ram preventers in maintaining a seal on an open hole.
• In 1972, Ado N . Vujasinovic was awarded a patent for a variation on the annular preventer known as a spherical blowout preventer, so-named because of its spherical-faced head.
• Drill pipe including the larger-diameter tool joints ( threaded connectors ) can be " stripped " ( i . e ., moved vertically while pressure is contained below ) through an annular preventer by careful control of the hydraulic closing pressure.