Blowout preventer locking apparatus and method

Locking apparatus in combination with a flow control device having a body with a flow passage therethrough, hydraulic cylinder means in which is disposed piston means for movement between first and second terminal positions and closure means connected to said piston means and movable in response thereto from an open position in which said flow passage is open to a closed position in which flow passage is closed thereby, said locking apparatus comprising:

• a. rod means axially aligned and movable with said piston means between first and second terminal positions;
• b. wedge means carried by said body and surrounding said rod means for longitudinal movement relative thereto;
• and
• c. slip means engaging said wedge means and radially movable, in response to said longitudinal movement of said wedge means, between a position not engaging said rod means and a position engaging said rod means to lock said closure means in said closed position;
• d. said wedge means comprising a piston assembly mounted in a cylinder movable in response to pressure applied to said cylinder to effect said longitudinal movement of said wedge means and latch means for selectively preventing said longitudinal movement of said piston assembly.

In combination with a ram type blowout preventer having a housing with a passageway through which a tubular member may pass, ram means movable between a non-sealing position in said housing, in which said passageway is open, and a sealing position in which said passageway is sealingly closed;

• and operator means for moving said ram means between said non-sealing and sealing positions;
• locking apparatus comprising:
• a. rod means connected to said operator means and reciprocable between first and second terminal positions in response to movement of said ram means between said non-sealing and sealing positions, respectively;
• b. slip means radially movable from a retracted position, not engaging said rod means, to a contracted position engaging said rod means, when said rod means is in said second terminal position, to lock said ram means in said sealing position;
• c. wedge means engaging said slip means and movable from a first position, holding said slip means in said retracting position, to a second position holding said slip means in said contracted position, said wedge means being carried on a piston assembly surrounding said rod means and disposed within a cylinder for reciprocal movement between first and second terminal positions, in which said wedge means is in its first and second positions, respectively, said piston assembly comprising latch means engageable with stop means in said cylinder to lock said piston assembly in either of its said terminal positions, said latch means being releasable to permit movement of said piston assembly between said terminal positions.

A method of operating a ram type blowout preventer having ram means movable between open and closed positions, hydraulic operator means for moving said ram means, and locking means for locking said ram means in said closed position, said method comprising:

• a. closing said ram means by applying a first pressure level to said operator means;
• b. activating said locking means by simultaneously applying said first pressure level to a portion of said locking means;
• c. moving said locking means into engagement with said operator means by applying a second pressure level, substantially less than said first pressure level, to another portion of said locking means;
• and
• d. locking said ram means in said closed position by reducing said first pressure level so as to lock said locking means in engagement with said operator means.