US Patent 8464785 Pipe guide arms for blind shear rams

A pipe shear ram assembly has a housing having a bore extending vertically therethrough for the passage of a pipe string. Ram blocks have blades positioned such that one slides over the other when the first and second ram blocks are moved toward each other to shear a well pipe. A pair of guide arms extend from one of the rams. The guide arms have tips protruding a greater distance than the blade. Each of the guide arms has an inboard wedge surface beginning at the tip and extending along a line that intersects the longitudinal axis for 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.