Pipe guide arms for blind shear rams

A pipe shear ram assembly, comprising:

• a housing having a bore extending vertically therethrough for the passage of a pipe string;
• first and second ram blocks having first and second blades, respectively, the first and second blades being positioned such that one slides over the other when the first and second ram blocks are moved toward each other along a longitudinal axis of the first and second ram blocks to a closed position;
• a pair of guide arms extending from the first ram block, the guide arms having tips protruding from the first ram block toward the second ram block a greater distance than the first blade;
• each of the guide arms having an inboard wedge surface beginning at the tip and extending toward the first ram block to a rearward end of the wedge surface along a line that intersects the longitudinal axis, each of the wedge surfaces being devoid of additional aligning structure from the tip to the rearward end for contact with and guiding the pipe string toward a bore axis of the bore in the event the first and second ram blocks are moved to the closed position;
• and
• each of the guide arms has an upper surface located at an elevation on the first ram that is lower than a lower surface of the first blade.

A pipe shear ram assembly, comprising:

• a housing having a bore extending vertically therethrough for the passage of a pipe string;
• first and second ram blocks having first and second blades, respectively, the first and second blades being positioned such that one slides over the other when the first and second ram blocks are moved toward each other along a longitudinal axis of the first and second ram blocks to a closed position;
• a pair of guide arms, each having a base joined to the first ram block, an inboard side portion extending from a forward end of the inboard side portion at an angle relative to the longitudinal axis;
• wherein
• a distance between the forward ends of the side portions is approximately a same distance as a length of the first blade measured between outboard ends and is less than a diameter of the bore:
• a distance between forward ends of the wedge surfaces is approximately a same distance as the diameter of the bore,
• a pair of recesses in the second ram block adjacent outboard ends of the second blade for receiving the guide arms when the first and second ram blocks move to the closed position, each of the recesses being defined by at least one recess wall;
• and wherein
• the guide arms are mounted to the first ram block so as to avoid sliding contact with the recess walls as the first and second ram blocks move to the closed position.

A pipe shear ram assembly, comprising:

• a housing having a bore extending vertically therethrough for the passage of a pipe string;
• first and second ram blocks having first and second blades, respectively, the first and second blades being positioned such that one slides over the other when the first and second ram blocks are moved toward each other along a longitudinal axis of the first and second ram blocks to a closed position;
• a pair of guide arms, each having a base joined to the first ram block, an inboard side portion extending forward from the base parallel with the longitudinal axis, and an inboard wedge surface extending from a forward end of the inboard side portion at an angle relative to the longitudinal axis;
• wherein
• a distance between the forward ends of the side portions is approximately a same distance as a length of the first blade measured between outboard ends and is less than a diameter of the bore;
• a distance between forward ends of the wedge surfaces is approximately a same distance as the diameter of the bore;
• and
• each of the guide arms has an upper surface located at an elevation on the first ram that is lower than a lower surface of the first blade.