Ram blowout preventer piston rod subassembly

A piston rod subassembly of a blowout preventer operator assembly, the piston rod subassembly comprising:

• a piston rod having a rod threaded interface and a rod shoulder on an outer diameter of the piston rod at a first end, and having a ram connector at a second end that is opposite of the first end;
• a preload ring having a ring threaded interface for engaging the rod threaded interface to couple the piston rod to the preload ring, wherein a protruding end surface of the piston rod protrudes past an end face of the preload ring when the piston rod is coupled to the preload ring and the rod shoulder engages a ring shoulder of the preload ring;
• a piston with a pocket for receiving the preload ring, the piston having an outer diameter seal selectively engaging an inner diameter of a piston chamber of a bonnet assembly of the blowout preventer operator assembly and being moveable within the piston chamber between an extended position and a retracted position, the piston further having a tail rod, the tail rod being a threaded elongated member extending in a direction opposite from the piston rod and threadingly engaging the bonnet assembly and inducing a rotation in the piston when an end load urges the piston towards the retracted position;
• and
• preload ring fasteners for coupling the preload ring to the piston to form a piston rod connection between the piston rod and the piston, such that the protruding end surface of the piston rod engages an interior surface of the pocket and a preload is induced in the piston rod connection.

A method of assembling a blowout preventer operator assembly with a piston rod subassembly, the method comprising:

• providing a piston rod having a rod threaded interface and having a rod shoulder on an outer diameter of the piston rod;
• threading the piston rod into a preload ring having a ring threaded interface for engaging the rod threaded interface to couple the piston rod to the preload ring, wherein a protruding end surface of the piston rod protrudes past an end face of the preload ring when the piston rod is coupled to the preload ring and the rod shoulder engages a ring shoulder of the preload ring;
• locating the preload ring in a pocket of a piston;
• and
• coupling the preload ring to the piston with preload ring fasteners to form a piston rod connection between the piston rod and the piston, such that the protruding end surface of the piston rod engages an interior surface of the pocket and a preload is induced in the piston rod connection.