| 摘要 |
A steel wear belt 27 having a prepared inner surface with an inner diameter large enough to pass over the weld upset on one end of a drill pipe tube 11 but too small to pass over the tool joints 17, 19 is installed about the pipe over a prepared outer peripheral surface thereof. Preferably the belt outer diameter is equal to or less than that of the tool joints. The belt is installed prior to one or both tool joints being welded to the tube. The belt is secured to the tube by a mounting layer 35 of high polymer material, e.g. plastics or elastomer, preferably self bonding and thermoset, between the prepared surfaces. The mounting layer may have a thickness in the range of 1/16 to 1/4 inch and an elastic modulus of not over 5% of that of steel, and an elastic shear strength of, e.g. 500 to 300 psi, and be stable up to 250 to 300 deg. F. The thickness of the mounting and its physical properties prevent stress concentration in the pipe due to mere attachment of the wear belt and due to restraint on pipe flexure imposed by the wear belt and prevent electrolytic corrosion between the pipe and wear belt. The pipe is plastic coated internally from tool joint to tool joint. The internal coating 25 and the wear belt mounting 35 are preferably cured simultaneously and may both be made of phenolic or epoxy, or preferably, phenolic-epoxy synthetic resin; otherwise an elastomer would be preferred for the belt mounting. <IMAGE> |
