Hydraulic Blow Out Preventers
Blow out preventers are used to secure the well and allow tubing and other production equipment to continue to flow in and out of the well. Preventers usually carry (2) sets of rams (1) for the tubing size and the other set blind. Preventers may have flanges or they also may be studded. Either way, preventers are necessary and very helpful should a problem with the wellbore arise.
An annular blow out preventer is considered a large valve that can seal around most objects that may be placed in your well bore. The "do-nut" type element allows you to seal around drill pipe, drill collars, casing, and wash-pipe. This type preventer is very useful in sealing off on equipment where needed that standard preventers may not.