Hydraulically actuated slip assembly

• Main Author: COX; DON C
• Format: Patent
• Language: English
• Published: 18.03.1986
• Edition: 4
• Subjects: EARTH DRILLING; EARTH DRILLING, e.g. DEEP DRILLING; FIXED CONSTRUCTIONS; MINING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR ASLURRY OF MINERALS FROM WELLS

A hydraulically operated slip assembly, connectible to a well head or well pipe handling machine and useful to intermittently grip pipe being run into or pulled from the well. The slip assembly has upper and lower plates with passages for pipe. Wedges, carrying unique slip systems, are positioned around the passages and slidably mounted for radial movement between guide plates extending from the upper and lower plates. The wedges are moved radially inward to grip pipe and radially outward to release pipe by a hydraulic cylinder, pivotally mounted aside the lower plate. When actuated to extend, the hydraulic cylinder rotates an inner bearing race and attached camming segments, which move the wedges inwardly to grip pipe. When the cylinder is actuated to contract, the bearing race and camming segments are rotated to pull the wedges outward radially, releasing pipe. The bearing outer race is housed in ring segments between and connecting the slip assembly upper and lower plates. The unique slip systems automatically increase pipe grip, on up or down movement of gripped pipe caused by very small loads. Outward force components, resulting from increased pipe grip, press the outer surfaces of the camming segments into ring segment grooves, developing forces which effectively prevent inadvertent or an purpose actuation of the cylinder from rotating the camming segments to ungrip pipe in the slip assembly.