Blowout preventer bonnet assembly

Abstract

A blow out preventer includes a main body with a main passage arranged therethrough, a ram movable between a first ram position in which the ram is spaced from the main passage and a second ram position in which the ram at least partly interrupts the main passage, and a bonnet releasably secured to the main body. The bonnet includes a hydraulic ram actuator coupled to the ram. The hydraulic ram actuator includes a primary piston arranged within a primary cylinder and fixed to a piston rod, and a secondary piston arranged within a secondary cylinder to be slidable on the piston rod. The primary piston and the secondary piston are each arranged to actuate the ram via the piston rod. The primary piston and the secondary piston each comprise a stroke length, the stroke length of the secondary piston being shorter than the stroke length of the primary piston.

What is claimed is: 
     
         1 - 33 . (canceled) 
     
     
         34 : A blow out preventer comprising:
 a main body comprising a main passage arranged therethrough;   a ram movable between a first ram position in which the ram is spaced from the main passage and a second ram position in which the ram at least partly interrupts the main passage; and   a bonnet releasably secured to the main body, the bonnet comprising a hydraulic ram actuator which is coupled to the ram, the hydraulic ram actuator comprising:   a primary piston arranged within a primary cylinder and fixed to a piston rod; and   a secondary piston arranged within a secondary cylinder so as to be slidable on the piston rod,   wherein,
 the primary piston and the secondary piston are each arranged to actuate the ram via the piston rod, and 
 the primary piston and the secondary piston each comprise a stroke length, the stroke length of the secondary piston being shorter than the stroke length of the primary piston. 
   
     
     
         35 : The blow out preventer as recited in  claim 34 , wherein,
 the piston rod comprises a mechanical stop, and   the secondary piston is configured to engage the mechanical stop so as to actuate the ram via the piston rod.   
     
     
         36 : The blow out preventer as recited in  claim 35 , wherein,
 the secondary cylinder further comprises a recess which is configured to receive the mechanical stop for at least a part of a stroke length of the piston rod.   
     
     
         37 : The blow out preventer as recited in  claim 34 , wherein the primary cylinder is arranged within the bonnet. 
     
     
         38 : The blow out preventer as recited in  claim 34 , wherein the bonnet further comprises:
 an attachment device; and   an actuator unit,   wherein,   the secondary cylinder is arranged in the actuator unit, and   the actuator unit is releasably fixed to the bonnet via the attachment device.   
     
     
         39 : The blow out preventer as recited in  claim 37 , wherein the bonnet further comprises:
 a first segmented latch ring comprising at least two latch ring parts, each of the at least two latch ring parts comprising a serrated outer profile which is configured to engage a first serrated surface on the bonnet;   a first segmented locking ring comprising at least two locking ring parts, each of the at least two locking ring parts being configured to engage with at least one of the at least two latch ring parts; and   at least one first fastener,   wherein,   the attachment device is fixed to the bonnet via the first segmented latch ring and the first segmented locking ring, and   the at least one first fastener fixes each of the at least two locking ring parts to either the bonnet or to the actuator unit.   
     
     
         40 : The blow out preventer as recited in  claim 39 , further comprising:
 a second segmented latch ring comprising at least two latch ring parts, each of the at least two latch ring parts comprising a serrated outer profile which is configured to engage a second serrated surface on the actuator unit;   a second segmented locking ring comprising at least two locking ring parts, each of the at least two locking ring parts being configured to engage with at least one of the at least two latch ring parts;   a locking device configured to selectively lock the ram in the second ram position; and   at least one second fastener,   wherein,   the locking device is fixed to the actuator unit via the second segmented latch ring and the second segmented locking ring, and   the at least one second fastener fixes each of the at least two locking ring parts to either the actuator unit or to the locking device.   
     
     
         41 : A blow out preventer comprising:
 a main body comprising a main passage arranged therethrough;   a ram movable between a first ram position in which the ram is spaced from the main passage and a second ram position in which the ram at least partly interrupts the main passage;   a bonnet releasably secured to the main body, the bonnet comprising a hydraulic ram actuator which is coupled to the ram; and   at least one hydraulic bonnet actuator which is operable independently of the hydraulic ram actuator and which is configured to move the bonnet relative to the main body from at least one of:
 a bonnet closed position in which the bonnet engages the main body to a bonnet open position in which the bonnet is spaced from the main body, and 
 from the bonnet open position to the bonnet closed position. 
   
     
     
         42 : The blow out preventer as recited in  claim 41 , wherein,
 the hydraulic bonnet actuator comprises a first piston extending from the main body to a first cylinder formed within the bonnet and a second piston extending from the main body to a second cylinder formed within the bonnet,   the first piston divides the first cylinder into a first operating chamber and a second operating chamber, and   the second piston divides the second cylinder into a third operating chamber and a fourth operating chamber.   
     
     
         43 : The blow out preventer as recited in  claim 42 , wherein the hydraulic bonnet actuator further comprises,
 a first connection channel which fluidly connects the first operating chamber and the third operating chamber, and   a second connection channel which fluidly connects the second operating chamber and the fourth operating chamber.   
     
     
         44 : The blow out preventer as recited in  claim 42 , wherein the hydraulic bonnet actuator further comprises,
 a first hydraulic supply channel which connects a first supply line to the first operating chamber, and   a second hydraulic supply channel which connects a second supply line to the fourth operating chamber.   
     
     
         45 : The blow out preventer as recited in  claim 44 , further comprising:
 a first extendable hydraulic supply line which is arranged to provide hydraulic fluid from the main body to the hydraulic ram actuator in the bonnet open position and in the bonnet closed position.   
     
     
         46 : The blow out preventer as recited in  claim 45 , wherein,
 the first extendable hydraulic supply line comprises a first tube which extends from the main body into a second passage in the bonnet,   the first tube is movable in relation to the second passage and is sealed against the second passage, and   the second passage is fluidly connected to the hydraulic ram actuator.   
     
     
         47 : The blow out preventer as recited in  claim 45 , further comprising:
 a second extendable hydraulic supply line which is arranged to provide hydraulic fluid to the hydraulic ram actuator in the bonnet open position and in the bonnet closed position.   
     
     
         48 : The blow out preventer as recited in  claim 47 , wherein,
 the second extendable hydraulic supply line comprises a second tube which extends from the main body into a third passage in the bonnet,   the second tube is movable in relation to the third passage and is sealed against the third passage, and   the third passage is fluidly connected to the hydraulic ram actuator.   
     
     
         49 : The blow out preventer as recited in  claim 47 , further comprising:
 a bonnet support rail arrangement which is configured to guide the bonnet between the bonnet closed position the bonnet open position,   wherein,   the first extendable hydraulic supply line is adapted to actuate a ram open movement of the hydraulic ram actuator, and   the second extendable hydraulic supply line is adapted to actuate a ram close movement of the hydraulic ram actuator.   
     
     
         50 : The blow out preventer as recited in  claim 49 , wherein the bonnet support rail arrangement comprises:
 a first support rail comprising a longitudinal axis, the first support rail being fixed to the main body;   a first pair of rail support bearings fixed to the bonnet and being spaced apart in the longitudinal axis of the first support rail;   a second support rail comprising a longitudinal axis, the second support rail being fixed to the main body; and   a second pair of rail support bearings fixed to the bonnet and being spaced apart in the longitudinal axis of the second support rail,   wherein,   the first pair of rail support bearings are arranged so that an imaginary plane which is generally perpendicular to the longitudinal axis of the first support rail in which a center of gravity of the bonnet lies is located between the first pair of rail support bearings, and   the second pair of rail support bearings are arranged so that the imaginary plane is located between the first second of rail support bearings.   
     
     
         51 : A blow out preventer comprising:
 a main body comprising a main passage arranged therethrough;   a ram movable between a first ram position in which the ram is spaced from the main passage and a second ram position in which the ram at least partly interrupts the main passage;   a bonnet releasably secured to the main body, the bonnet comprising a hydraulic ram actuator which is coupled to the ram; and   a first extendable hydraulic supply line, the first extendable hydraulic supply line being arranged to provide hydraulic fluid from the main body to the hydraulic ram actuator in a bonnet open position and in a bonnet closed position.   
     
     
         52 : The blow out preventer as recited in  claim 51 , wherein,
 the first extendable hydraulic supply line comprises a first tube which extends from the main body into a second passage in the bonnet,   the first tube is movable in relation to the second passage and is sealed against the second passage, and   the second passage is fluidly connected to the hydraulic ram actuator.   
     
     
         53 : The blow out preventer as recited in  claim 52 , further comprising:
 a second extendable hydraulic supply line which is arranged to provide hydraulic fluid to the hydraulic ram actuator in the bonnet open position and in the bonnet closed position.   
     
     
         54 : The blow out preventer as recited in  claim 53 , wherein,
 the second extendable hydraulic supply line comprises a second tube which extends from the main body into a third passage in the bonnet,   the second tube is movable in relation to the third passage and is sealed against the third passage, and   the third passage is fluidly connected to the hydraulic ram actuator.   
     
     
         55 : The blow out preventer as recited in  claim 53 , wherein,
 the first extendable hydraulic supply line is adapted to actuate a ram open movement of the hydraulic ram actuator, and   the second extendable hydraulic supply line is adapted to actuate a ram close movement of the hydraulic ram actuator.   
     
     
         56 : The blow out preventer as recited in  claim 51 , further comprising:
 a bonnet support rail arrangement which is configured to guide the bonnet between the bonnet closed position and the bonnet open position.   
     
     
         57 : The blow out preventer as recited in  claim 54 , wherein the bonnet support rail arrangement comprises:
 a first support rail comprising a longitudinal axis, the first support rail being fixed to the main body;   a first pair of rail support bearings fixed to the bonnet and being spaced apart in the longitudinal axis of the first support rail;   a second support rail comprising a longitudinal axis, the second support rail being fixed to the main body; and   a second pair of rail support bearings fixed to the bonnet and being spaced apart in the longitudinal axis of the second support rail,   wherein,   the first pair of rail support bearings are arranged so that an imaginary plane which is generally perpendicular to the longitudinal axis of the first support rail in which a center of gravity of the bonnet lies is located between the first pair of rail support bearings, and   the second pair of rail support bearings are arranged so that the imaginary plane is located between the first second of rail support bearings.