1. Application
Equipped with hydraulic control system, the annular BOP seals off annulus in different sizes, when drilling pipes are in use in the hole. The annular BOP can also seal off the hole when no drilling tool in it. The annular BOP can seal off the annulus between the drill stem, core tool, cable, wire rope and well barrel, in case blowing out happens during logging, or coring, etc. and When used in conjunction with pressure relief valve and accumulator, the annular BOP allows tripping service using 18º non-threaded butt-welded pipes.

2. The annular BOP is controlled by hydraulic control system. When it is closed, the high pressure oil is directed to the closing chamber positioned in the lower side of the piston, causing the piston to move upward. The spherical rubber core is compressed by the moving piston. Because of the lid limitation the packing unit can not move upward but be compressed to the center of the well, to tightly hold the drilling tool or seal off the well, so that sealing-off the well can be implemented.

3． Operating Requirements
（1）When well blowouts, the annular BOP can be used to control the well, but it can not be closed for long time. For one hand the rubber core can be easy damaged, on the other hand the BOP itself has no locking mechanism. It can not be used to close the well unless in special circumstance.
（2）It is necessary to use the drilling tool with 18 degree bevel, when the annular BOP is used to run the drilling operation. The drilling tool should be passed through the joint slowly; the rubber protecting hoop should be unfixed.
（3）When the annular BOP in closed condition, the shut-in pressure is below 5Mpa, the drilling tool can be moved up or down, but rotating pipe is strictly not allowed.
（4） It is not allowed to open the annular BOP to relieve the well pressure in order to avoid the rubber core damaged.
（5） Be sure to check the well whether the annular BOP is in the full-open position every time after opening the well in order to prevent the rubber core from damage.
（6） Clean the inside of the BOP after well cementing operation is finished in order to keep its closing and opening flexibly.
（7） More attention should be paid to ring gaskets and steel ring grooves not to be damaged when installing or uninstalling it.（8） After entering into the destination layer at each tripping, it is necessary to close the rubber core once to test its closing function. It should be replaced at once if it is out of working.
（9） According to the applicable standard, the pressure test of the annular BOP should be performed periodically.

List of part detail

No.	Description	Quantity	Material	Remarks
1	Cover	1	ZG30CrMo
2	Globe rubber core	1	Nitrile rubber
3	Sustain ring	1	ZG30CrMo
4	piston	1	ZG30CrMo
5	Housing	1	ZG30CrMo