Hydraulic External Cutter

Description: Hydraulic External Cutters are hydraulically actuated mechanical tubing and drill pipe cutters. The cutters provide fast, efficient, smooth cutting and are capable of cutting and recovering strings of tubing or drill pipe. The cutter knives are fed entirely by pump pressure, thus giving the operator sensitive control.

Operation:

To operate, assemble the cutter using the proper size and type of piston assembly. Run the cutter into the hole to cutting depth. When cutting depth is reached, open the fill-up and standpipe valves just enough to shear the shear pins. Begin slow rotation - 15 to 25 rpm. Slowly close the bypass valve again to pump fluid down the working string. This will begin feeding the knives to start the cut. The amount of pressure and gallons per minute required depends on the cutter size and piston assembly being used. Use extreme caution to avoid surging of pump pressure when starting a cut. Pressure surging causes the string length to contract and expand, moving the cutter up and down. This motion prevents the knives from remaining in one position when starting a cut. A rough chattering action followed by the smoothing of the rotary will signal the completion of the cut. Bring the cut section out and strip it from the wash pipe. Do not spud coming out of hole.

Construction:

Simple, yet rugged, Bowen Hydraulic External Cutters are composed of a top sub, body, guide, a set of knives, and a segmented piston assembly. Two shear pins hold the piston in a "running in" position until they are sheared to begin the cut.The piston assembly is composed of a rubber ring and a set of interlocking, conical piston segments. The segments are held in a contracted position by a tough rubber ring stretched around the end of the segments in a suitable groove. Each piston segment has a fluid passage which is engineered to simultaneously pass fluid for flushing, cooling, and restricting the fluid flow for ample pump down force on the knives to effect the cut.